[Emc-users] Free Bandit CNC controller (stepper)

[cogoman via Emc-users]

This Bandit stepper controller was working about 5 years ago when it 
stopped doing any circular interpolation.  The machine it was 
controlling had 1.5 amp steppers, so it was easy to replace it with GRBL 
and the CNC shield.


  The power supply (if I remember correctly) was about 75 volts, and 
you can see from it's size it had a lot of current capability.  The (3) 
stepper drivers are linear, and could handle stepper motors up to about 
7 amps.


  Someone on this list might be able to put the power supply to good 
use on a servo machine.  That's why it's offered for free, but we can't 
keep it forever (I'd hate to have to scrap it.)


*  It can be picked up near the Seaview Square Mall in NJ by arrangement.*

I hope someone can make use of it.

Bandit CNC controller

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Re: [Emc-users] IJK vs R

[cogoman via Emc-users]

I believe that R arcs that are 90 degrees or less are going to come out 
very close to the IJK versions, but if you want a full circle, it's 
better to break it up into 4 90 degree arcs.  I don't know just where 
radius arcs start to diverge from IJK arcs, but I would guess that 180 
and 360 degrees are problem spots.


On 2/10/22 16:30, Les Newell wrote:
That code is testing the 180 degree issue, which is not usually a 
major problem as far as accuracy is concerned. Try using a R value of 
5.002, instead of 5.0025. In this case the arc does not technically 
fit. Some controllers throw a fit and some quietly fudge the radius to 
fit. I think LCNC fudges the radius, adding a tiny amount of error but 
it won't be enough to measure.


Try using an R arc that's really close to a circle. Tiny rounding 
errors in the X,Y coordinates can move the arc all over the place.


Les

On 10/02/2022 00:17, andy pugh wrote:

Thde docs state that a 7% difference was seen, but with some brief
experimentation I can't see it:

F1000
G0 X0 Y0
G2 X10 Y0.1 R5.00025
G0 X0 Y0
G2 X10 Y0.1 I5.0 J0.05
M2





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Re: [Emc-users] who has used thin client pcs

[cogoman via Emc-users]

I have found that the "Magic Pixie Dust" for a damp shop comes in a 
spray can called Caig deoxit.  The trick is pairing a contact cleaning 
solution with an appropriate oil that seals the contacts so that oxygen 
can't get into the connection.


A church building is a great place for humidity related failures.  Warm 
on Sunday morning and Wednesday evening, cool and damp the rest of the 
time.  We have a 6 -DVD duplicator with a hard drive inside.  After 
about a year 2 of the DVD drives were acting up, and if left on for 
about a half an hour, the OS (probably DOS) would lock up and need to be 
power cycled.


I sprayed every connector I could get apart (mostly SATA), and it came 
back to life, and has been working well for many years since.


I even tried it on a processor socket to see if the oil would mess up 
signal integrity and it didn't, so I think the oil has a dielectric 
coefficient near that of air.



On 2/10/22 11:19, Les Newell wrote:
The version running a 4 core GX-415 processor should be fine for 
LinuxCNC.  I use Wyse 5020 thin clients on my lathe and router, which 
use the same SOC. The 2 core version is a bit slow if you are using it 
with Ethernet FPGA cards. I used one on my lathe for a couple of years 
and it occasionally popped up a latency warning, though the machine 
appeared to run fine.


I have to admit I'm a big fan of thin clients. My workshop is pretty 
damp and when I used desktop based PCs I probably averaged about 1 
failure every year or so. Since swapping to thin clients about 5 years 
ago I have had one failure and that was down to my carelessness, 
rather than a spontaneous failure.


Les


On 10/02/2022 00:01, andrew beck wrote:

hey everyone

just wondering who has used the thin client computers
i am looking for a fanless pc that i can buy in oceania

https://www.youtube.com/watch?v=tVXn_fEbDTs

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Re: [Emc-users] F-Engrave and LinuxCNC scripting

[cogoman via Emc-users]

One option would be to generate one big G-code file, with the 
appropriate M-CODE to break it up, and an operator's comment to let you 
know which section is coming up next.


1.   The operator would get a message like:

  (Prepare to carve Billy G's name)

2.   Put the part in the vise and hit run.

3.   The operator get's a message:

  (Prepare to carve Billy G's nickname)

4.   Flip the blank and hit run.

5.   The operator get's a message:

  (Prepare to carve Terry M's name)


and so on.


  It would probably really mess up your back plot, but you could have 
your program generate each individual section with indexed names, like:


Names001.ngc

Names002.ngc

ETC.

So you could preview what F-Engrave did, but also have your program 
generate:


Names-ALL.ngc

for the actual cutting once you are satisfied with the g-code.


On 2/24/22 12:21, andy pugh wrote:

On Thu, 24 Feb 2022 at 01:42, Ralph Stirling
 wrote:

If you wanted totally automated, you could use linuxcncrsh.

I don't think that linuxcncrsh is appropriate here, that is for remote
connection. I would plan on running the controlling script on the
actual controller PC.

It looks like what I intend can be done with the python interface:

program_open(string) - open an NGC file.
auto(int[, int]) - run, step, pause or resume a program.

Though the documentation on "auto" could afford to be a bit more
forthcoming on what the parameters do, or are for...

(Looking at emcmodule.cc it appears that the first integer is the command:
#define LOCAL_AUTO_RUN (0)
#define LOCAL_AUTO_PAUSE (1)
#define LOCAL_AUTO_RESUME (2)
#define LOCAL_AUTO_STEP (3)
#define LOCAL_AUTO_REVERSE (4)
#define LOCAL_AUTO_FORWARD (5)

And the optional second integer is the start line for run-from-line )




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Re: [Emc-users] Mini-PC

[cogoman via Emc-users]

I recommend the techniques in this web page:


https://www.grc.com/haystack.htm


I enjoy pointing out the smarts of Steve Gibson.


I've set up an Epson ET-2650 printer as a WIFI access point, and since 
the interface for entering the password is so awful, I created a 
password specifically meant to be easy to enter on that printer.  It is 
still over 16 characters long, and has something from caps, lower case, 
numbers and special characters.  That should keep lurkers from wasting 
our paper with nonsense.


On 9/13/20 5:18 AM, Chris Albertson wrote:

You could prevent this by not using "password" or "123" as your network
password.

I don't enable the wifi. I have a neighbor that will use 100gb a month

using my bandwidth instead of his with his smartphone.  So all my
networking is hard wired.





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Re: [Emc-users] Machmaker USB -> Parallel

[cogoman via Emc-users]

  The point of 300,000 steps per second is in the difference between 
the fastest speed you want your motors turning at and the second fastest 
speed you want your motors turning at.  If you want to be able to run at 
10,000 steps per second, you can't use a a system that has a maximum 
step rate of 10,000 steps per second.


_--___

    50uS    50uS

Here is a plot of a system that maxes out at 10,000 steps per second.  
50Us for the high and 50uS for the low makes for one clock pulse.  The 
next slower speed would be 6,666 steps per second.


__--

    50uS 50uS 50uS    50uS 
    50uS


Trying to change the speed of a stepper motor from 7,000 steps per 
second to 10,000 steps per second in one jump would not succeed.  That's 
why you want the fastest top speed you can get, because it's nicer to 
jump from 9,980 steps per second to 10,000 steps per second.  I don't 
mean to say that this is the STM32F104's granularity with klipper3d's 
software, I don't know what the granularity is.


Here is the benefit of this use of the STM32F104.

1. Use LinuxCNC on a hand-me-down X86 computer that would have otherwise 
been thrown away.


2. Not be speed limited by the latency test results (unless they were 
terrible).


3. Not have to buy an Orange Pi which I don't have.

4. Make it possible to control a desktop machine with a hand-me-down PC 
and a $14 GRBL setup. 
(http://www.zyltech.com/arduino-cnc-kit-uno-r3-shield-4x-a4988-drivers/)


The drawback of STMBL (not much of a drawback) is I would need to buy a 
MESA card for the real time issues.


If I remember properly, the granularity for a MESA card is 10nS per pin 
change.  No one would try running their stepper motor at 50,000,000 
steps per second, but it makes going from 10,000 steps per second to the 
next higher rate a piece of cake for the motor.






On 8/15/20 12:57 AM, Chris Albertson wrote:

  What is the point of 300,000 steps per second if the
motos cn't move that fast.




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Re: [Emc-users] Machmaker USB -> Parallel

[cogoman via Emc-users]

On 7/23/20 2:15 PM, Chris Albertson wrote:

What is really needed is for someone to write firmware for the common
STM32F103 "Blue Pill".  These have the hardware to do things like step gen
and quadrature decode  at MHz speeds and talk to the PC over SPI I2C or USB
and cost under $3 from 100 different vendors.   I use these for motion
control when I can but not with Linux CNC. It is really "just a matter
of software" but I'm not about to spend months of my time to save the cost
of a 7i92.


May I suggest the shoulders of KevinOConner to stand on.

  Check 
out   https://www.klipper3d.org/


He has set up a 3D printer program that uses python on the Raspberry PI 
for the G-Code interpreter.  He used OctoPrint to feed the USB serial 
port, but the arduino doesn't have to interpret G-Code, so with an 
arduino he can max out at 102,000 steps per second, with the STM32F104 
in the Blue Pill Board he can max out at 360,000 steps per second, both 
with 3 steppers stepping.


                    https://www.klipper3d.org/Protocol.html

                    https://www.klipper3d.org/Features.html

  The benchmark is a little cryptic to me, but I think it says the blue 
pill board can step three steppers at less than 10uS per step max (for a 
$3 board).  If I read this properly, you can sink up 2 blue pill boards 
and control 6 to 8 steppers.  Yes there are limit switches connected.  
It also handles the slow speed PID control of  a heated bed and extruder.


  I would like to see LinuxCNC set up to control my router through the 
blue pill board (or two) without needing the OctoPrint, or the Klipper3D 
python interpreter.  I have been running my router with GRBL, and though 
it's an amazing feat of programming prowess, sometimes wrestling with 
FreeCAD and either FreeCAD's PATH toolbench or JSCUT makes me wish I had 
the subroutines, named variables, math, and looping constructs LinuxCNC 
makes available.  Many times I've spent hours or days doing something I 
felt confident I could do in LinuxCNC in about an hour.


  I would like to see LinuxCNC able to control a small machine through 
a $14 CNC controller.


http://www.zyltech.com/arduino-cnc-kit-uno-r3-shield-4x-a4988-drivers/

The protocol and the microcontroller software is already done, though 
I'd guess it doesn't use synchronous transfers, but just buffers the 
steps to keep latency from stalling the steppers.






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Re: [Emc-users] found a harmonic drive set of .stl's on thingiverse

[cogoman via Emc-users]

While this is late in this thread, and I don't know if this has been 
covered, but hackaday had an article on a guy who has a program to 
generate cycloidal gears.  They may not have as great gear ratios as a 
harmonic drive, but might help someone looking over this thread, so here 
goes:


https://hackaday.com/2020/08/14/robotic-arm-sports-industrial-design-3d-printed-cycloidal-gears/

That is for the hackaday article,

https://forum.onshape.com/discussion/7567/cycloidal-gear-generator

That is where he posted the software.

On 7/19/20 7:58 PM, Gene Heskett wrote:

Hopefully I can put it together correctly, there are no text files and I
haven't the foggiest what bearings I'll need, or what brand of grease.

Cheers, Gene Heskett




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Re: [Emc-users] off topic: pwm with a stepper driver/motor

[cogoman via Emc-users]

I recently discovered geared stepper motors.

http://www.zyltech.com/nema-17-stepper-motor-geared-planetary-gearbox-1-7-a-3-1-nm-435-ozin/

I've been happy with zyltech in the past.  I bought one of these for 
evluation, but the specs seem to be great for CNC. Low enough current to 
work with a stepstick, High enough torque for a fairly powerful machine, 
and less than 4 mH inductance should let it step pretty fast.


5.18:1 gear ratio should reduce that 4 meter spur gear, but the link 
below has higher gear ratios that would reduce that spur gear greatly! 
Backlash could be a problem for CNC, but if you are only going one way, 
the less precision gearboxes might be fine.


https://www.omc-stepperonline.com/geared-stepper-motor/?sort=p.price&order=ASC

Once you visit the stepperonline web page you know as much about them as 
I do, but their offerings might be just right for your application.


On 7/9/20 2:23 PM, R C wrote:

Hello,

this is (probably) off topic, been seen that happen.  If it is please 
ignore it.



I am building a "motorized"  telescope mount (dobsonian) with what is 
called an equatorial platform, it has 3 axis which I am going to drive 
with stepper motors.



The stepper motors I use with a stepper driver, those common DM542 
ones, the stepper motors themselves are 2A and 1.8 degrees per step.



What I want to accomplish with the equatorial platform)  (it 
compensates for the rotation of the earth) is that,  the start and end 
position accuracy is not that important,  smooth and 
constant/consistent movement is.  for the azimuth/altitude precision 
is not a really big deal, but you'd want to move these 2 axis  
somewhat swift.



So there are a few factors to decide.


I probably want micro stepping,  what settings on the driver for 
pulses per rev, is best to use (or is that just trial and error?)



As with PWM itself, I am probably just not too familiar with it. From 
what I understand, the voltage I use for the motors determines how 
fast I can go (I am going to use a 48V switching power supply).



as for PWM,  I can of course  change the length of the pulse itself  
and, independently, change the time between two pulses. What is the 
relation ship there?  WHat does a longer  width of the pulse itself 
do?  and what exactly does a longer gap between the pulses do (of 
course the wider the gap between two pulses the slower the motor turns).



for, especially, the equatorial platform, I want to avoid "jerking" 
it,  meaning  starting and stopping the stepper motor as little as 
possible and just go at a 'slow' constant speed.




sorry if totally of topic


thanks,


Ron



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Re: [Emc-users] pot for vfd

[cogoman via Emc-users]

I second the motion to try contact cleaner.  I use Caig DeoxIT that i 
bought from Parts Express. It's a little expansive, but worth every 
penny!   At my church we had a CD/DVD duplicator that started acting up. 
I pulled apart all the cable connections and sprayed them and put them 
back on a few times and it went back to working like normal.  The church 
building is warm one day a week, and then damp the rest of the time 
(does that remind you of your shop?) The stuff has a lubricant that's 
left behind to seal the contact points to keep water and oxygen out.


On 6/5/20 3:36 PM, N wrote:

a few years ago i switched my lathe to a 3 phase motor and vfd
i added a 10k pot to the lathe panel
recently the motor speed started fluctuating
i switched the vfd back to using the pot on it's front panel
no more fluctuation
can someone recommend a 10k pot that will handle the vibration

Farnell have, many different kinds, simple and multiturn precision. Also 
digital but they do not have a knob ;/

Nicklas Karlsson


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Re: [Emc-users] On Motorizing a BS-1 clone

[cogoman via Emc-users]

On 5/29/20 8:44 PM, Gene Heskett wrote:

In this case, openscad gives me the tools I want right now, and I could
even do a set of gears for stage 2 of the reduction since that spacing
is almost too close for a belt coupling. So by using the correct tooth
profiles it could make a very usefull gearset, no belt at all, and a
higher reduction at the same time. But would those teeth be strong
enough. Worth a try IMO. And a swarf cover from the printer should be
doable.



Strength of 3d printed parts is a deep subject.  PLA if done right can 
be pretty strong, but other filaments done right are stronger.


I like this video showing how a veteran at 3d printing goes about 
refining his process for printing in nylon.


https://www.youtube.com/watch?v=5MFX1whwjGg

Here is a video where some guys test out different filaments on a 15 
horsepower outboard motor.


https://www.youtube.com/watch?v=scUEEQyC0GI


Keep in mind, the odor will be much worse using any filament besides 
PLA, and most will need a hot end that can do the higher temperatures.


Also with higher temperatures you might want to put a box around the 
printer to keep drafts from messing up a print. One guy uses grow tents 
around his printers.






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Re: [Emc-users] Correct use of subroutines

[Cogoman]

That nifty utility sounds like an early, buggy, limited version of SED, the 
stream editor.

  I am a big fan of SED. Available for Linux, Windoze, and probably for OSX. 
The learning curve is steep, but the power is amazing, and as far as I know, 
the file of swap rules can get bigger than you will ever need.
Sent from my Kyocera Rise

Gregg Eshelman  wrote:

>--- On Sun, 5/12/13, Rafael Skodlar  wrote:
>
>> > It can be used as one, certainly, but then so can
>> Postscript.
>> >
>> 
>> By that logic, we would program web sites code in assembler.
>> But then 
>> millions use inches and feet even when they tweet ...
>
>You can also do crazy things such as writing an HTML document completely in 
>UTF-8 codes, they're &# followed by 4 digits and a ; Leading zeros can be left 
>out.
>
>7 characters to encode 1, and for any character in English and several other 
>languages, completely pointless when extended ASCII contains all the required 
>characters, including left and right single and double quotes.
>
>That brings up a nifty utility I had someone create, it's a text string 
>swapper. The input is simple, just a text file with pairs of lines. The 
>program has a user interface to enter the swaps but it's easier to write the 
>input file in a text editor.
>
>The contents of the first line will be swapped with the contents of the 
>second, third with fourth etc.
>
>I used it for 'cleaning' HTML prior to converting ebooks and other documents 
>to read on a Palm LifeDrive because Palm OS doesn't support unicode. (Palm OS 
>5 was new enough it should have had Unicode!)
>
>It could be useful for doing extremely fast, multiple swaps on any type of 
>text file. Sure you can do find and replace all in Word and other text editing 
>software, but just one at a time. This utility can do many swaps in a single 
>pass.
>
>For example you want to change all instances of G0 to G00 *and* all instances 
>of 1002 1005 to 1002-1006 (including the space between) *and* all instances of 
>meep with Beep, this can do it.
>
>However it does have a bit of a bug. The number of swap pairs it can handle is 
>limited. Try to do too many and it'll bugger up both the file you're working 
>on and the swap pairs input file. I tried to make a universal UTF-8 code to 
>ASCII input file and it choked on it.
>
>I do have the source code and compiled versions if anyone wants them to tinker 
>with and possibly fix the bug. It was written in (IIRC) Visual C 2005 - some 
>part of Microsoft's 2005 programming suite. It works perfectly fine as long as 
>it's not pushed past its limit. ;)
>
>I didn't experiment to find out the maximum number of swap pairs before it 
>goes gaga. Since I didn't write it, I've no idea where to look for the bug or 
>what'd be causing it. The author did it for free, got the essential 
>functionality working. Good enough!
>
>On the expanded functionality wishlist is the ability to load different swap 
>lists for different uses. As it is, it just reads replacementfile.txt in the 
>same folder as the executable so to use more than one the user has to keep 
>other lists elsewhere or rename the one to use.
>
>It could even be used (if the bug is fixed) for multiple pass encryption and 
>decryption by using a series of swap lists to re-arrange all the characters.
>
>If you're interested I can zip up the lot, including replacement lists I made, 
>and send it to you.
>
>--
>Learn Graph Databases - Download FREE O'Reilly Book
>"Graph Databases" is the definitive new guide to graph databases and 
>their applications. This 200-page book is written by three acclaimed 
>leaders in the field. The early access version is available now. 
>Download your free book today! http://p.sf.net/sfu/neotech_d2d_may
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from a single console and one unified framework. Download a free trial.
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Re: [Emc-users] Correct use of subroutines

[Cogoman]

Sent from my Kyocera Rise

Gregg Eshelman  wrote:

>--- On Sun, 5/12/13, Rafael Skodlar  wrote:
>
>> > It can be used as one, certainly, but then so can
>> Postscript.
>> >
>> 
>> By that logic, we would program web sites code in assembler.
>> But then 
>> millions use inches and feet even when they tweet ...
>
>You can also do crazy things such as writing an HTML document completely in 
>UTF-8 codes, they're &# followed by 4 digits and a ; Leading zeros can be left 
>out.
>
>7 characters to encode 1, and for any character in English and several other 
>languages, completely pointless when extended ASCII contains all the required 
>characters, including left and right single and double quotes.
>
>That brings up a nifty utility I had someone create, it's a text string 
>swapper. The input is simple, just a text file with pairs of lines. The 
>program has a user interface to enter the swaps but it's easier to write the 
>input file in a text editor.
>
>The contents of the first line will be swapped with the contents of the 
>second, third with fourth etc.
>
>I used it for 'cleaning' HTML prior to converting ebooks and other documents 
>to read on a Palm LifeDrive because Palm OS doesn't support unicode. (Palm OS 
>5 was new enough it should have had Unicode!)
>
>It could be useful for doing extremely fast, multiple swaps on any type of 
>text file. Sure you can do find and replace all in Word and other text editing 
>software, but just one at a time. This utility can do many swaps in a single 
>pass.
>
>For example you want to change all instances of G0 to G00 *and* all instances 
>of 1002 1005 to 1002-1006 (including the space between) *and* all instances of 
>meep with Beep, this can do it.
>
>However it does have a bit of a bug. The number of swap pairs it can handle is 
>limited. Try to do too many and it'll bugger up both the file you're working 
>on and the swap pairs input file. I tried to make a universal UTF-8 code to 
>ASCII input file and it choked on it.
>
>I do have the source code and compiled versions if anyone wants them to tinker 
>with and possibly fix the bug. It was written in (IIRC) Visual C 2005 - some 
>part of Microsoft's 2005 programming suite. It works perfectly fine as long as 
>it's not pushed past its limit. ;)
>
>I didn't experiment to find out the maximum number of swap pairs before it 
>goes gaga. Since I didn't write it, I've no idea where to look for the bug or 
>what'd be causing it. The author did it for free, got the essential 
>functionality working. Good enough!
>
>On the expanded functionality wishlist is the ability to load different swap 
>lists for different uses. As it is, it just reads replacementfile.txt in the 
>same folder as the executable so to use more than one the user has to keep 
>other lists elsewhere or rename the one to use.
>
>It could even be used (if the bug is fixed) for multiple pass encryption and 
>decryption by using a series of swap lists to re-arrange all the characters.
>
>If you're interested I can zip up the lot, including replacement lists I made, 
>and send it to you.
>
>--
>Learn Graph Databases - Download FREE O'Reilly Book
>"Graph Databases" is the definitive new guide to graph databases and 
>their applications. This 200-page book is written by three acclaimed 
>leaders in the field. The early access version is available now. 
>Download your free book today! http://p.sf.net/sfu/neotech_d2d_may
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"Graph Databases" is the definitive new guide to graph databases and 
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Re: [Emc-users] variable reluctance motors

[Cogoman]

I believe I have seen them used to advance the roller on an electric 
typewriter. When the current is off, there's no cogging like hybrid steppers 
have. That makes adjust paper height by hand seem normal for a typewriter.
Sent from my Kyocera Rise

Roland Jollivet  wrote:

>Hi All
>
>Can anyone tell me if they are actually using variable reluctance motors as
>servos on CNC machines.
>
>I find it odd that such a simple motor is not in greater use. The only
>place I've ever seen them used was to position the head on old 8in floppy
>drives.
>Maybe they just don't have a good power to size ratio?
>
>Regards
>Roland
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Re: [Emc-users] Closed loop stepping system

[cogoman]

On 04/10/2013 07:18 AM, Javier Ros wrote:
> Is apparently a stepper motor that is controlled as a brushless.
> Essentially a stepper is a brushless. This needs a encoder, probably one
> with a index pulse correctly positioned,
> so that the electronics can compute the switching accurately.
>
> This means, even if the control of the drive looks like a STEP DIR control,
> internally there are position and current loops, theoretically such a drive
> could offer, velocity and
> current control (I've not checked for the above reference).
>
> The only limitations seem to be related to control at hih rpms, performance
> degrades in comparison with brushless. I would say that this is related to
> the higher pole count of the steeper,
If you were to design one of these from the ground up, since position 
would be verified from a 10,000 step encoder, and the stepper would be 
run as a type of servo motor, the stepper driver would function much 
differently.  It would generate commutation from the encoder, then it 
would drive a current into one coil to draw the motor towards the 
commanded position.  PID would decide how hard to hit the motor by the 
difference between commanded position and current encoder position.  
Since this works like a servo and not a stepper with feedback, the 
stepper motor could be designed with less steps per rev. less steps per 
revolution would require less soil current reversals, and would allow 
the motor to step faster. If a 1mH coil standard stepper could be driven 
to 3000 RPM,  one with 100 steps per rev instead of 200 could be driven 
at 6000 RPM. One with 50 steps per rev could be driven at 12000 RPM. The 
control circuit would have to do some tricky math to keep cogging to a 
minimum, but it's likely possible to make a very fast but still accurate 
stepper system this way.

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Re: [Emc-users] Cecil Thomas - CNC'd Watchmakers Lathe

[Cogoman]

Getting that alu tape drum off the shaft so you can fit something else is a 
problem, they are pressed on, interference fitted.

I think I'd try a nutcracker.
Sent from my Kyocera Rise

Gene Heskett  wrote:

>On Thursday 04 April 2013 09:23:01 Gregg Eshelman did opine:
>
>> --- On Thu, 4/4/13, John Stewart  wrote:
>> > I'm looking for ideas here.
>> > 
>> > A Unimat SL1000, MK1 landed on my desk last Saturday. It's
>> > mine if I want it. Have been thinking of taking some of my
>> > CNC parts kicking around home and using them, but I don't
>> > think using a 5i25 + 7i76 + Nema 34 steppers is great.
>> > 
>> > So, with a little lathe like this, if I go with NEMA 17 "3D
>> > Printer" steppers (think Reprap or one of the Thingverse
>> > machines), what would be the best, least expensive way of
>> > driving these steppers from a LinuxCNC setup?
>> 
>> Even 17's would dwarf that Unimat. I'd try some motors from printers or
>> old 5.25" full height floppy drives. I just happen to have a pair of
>> Tandon single sided 5.25" drives I've been trying to give away for a
>> while. ;) Had them on a TI-99/4A years ago before upgrading to double
>> sided drives.
>> 
>> The drive motors for spinning the disks might also be useful for micro
>> CNC with encoders added. I think they have tachometers built in.
>> 
>They would probably be pretty puny for x-z drives even on that small a 
>lathe.  They were normally belted to the spindle, and belt slippage on the 
>lathe would destroy any accuracy unless you also put scales on it.  The 17 
>class steppers might be overkill. but at least you can microstep them.
>
>> Even cooler would be using the motor control boards from the drives.
>> They do step and direction for the head steppers and on/off for the
>> drive motors. 'Course they have rather poor resolution with only 40
>> normally accessible steps, though that's not a hard limit, there was
>> software for increasing the number of tracks on disks for some
>> computers.
>
>Steps available are virtually unlimited.  The driver SW in the computer 
>usually steps them outward, either until it hits a mechanical limit & sits 
>there hammering the stop till enough steps have been issued that the 
>computer knows it has to be at track zero ( racket you hear at bios bootup 
>from any pc with a floppy in it, or if fancy driver, the track zero switch 
>closes to indicate its at track zero.  Stepping the other way is limited in 
>the drive by the head carriage hitting the spindle mechanics but if that 
>limit is removed, there is not any other limit.
>
>The biggest problem will be the low voltage it runs on.  The disk drives 
>board will fail at the voltages we commonly use for steppers, even the toy 
>stuff we generally use is 24 volts, and that is enough to cook the floppy 
>board because they do not chop for current control, they power up, do the 
>step and shut the current off 40 milliseconds or so later if no more steps 
>come in since there is not any torque pushing on them, the normal steppers 
>cogging is sufficient holding power.
>
>The next problem is the speed they can step.  At the voltages they do run 
>at, and at no more mass than they have to move, the maximum step rate is 
>nominally 6 ms per step.  Mechanically geared down for accuracy, that is 
>not going to be very fast at all.
>
>Synopsis: Look for a small chinese stepper board that can microstep with 
>chopper controlled current, and hit the surplus places looking for 4 wire, 
>not more than 12 volt, probably $12 or so, steppers.  I have a few, rated 
>at 24 volts, which means they'd be pretty slow on 24 volts, but I didn't 
>buy them for motors, but as generators, turned by hand they output a nice 
>pulse for a jog pendent.  But my round tuit came up missing.  :)
>
>Those head steppers out of the old tandon's that drive the head carriage 
>via the thin steel tape, can be made to put out considerably more torque, 
>and faster by 5x or so, if driven by a xylotex board and a 24 volt supply.  
>But the xylotex board doesn't do idle current reduction, just on & off via 
>the enable pins, so the motor temps need to be watched.  Getting that alu 
>tape drum off the shaft so you can fit something else is a problem, they 
>are pressed on, interference fitted.
>
>Interesting what if problem. :)
>
>> I wonder if it'd be possible to hack the control board (which is
>> separate from and much smaller than the data read/write board) to work
>> as a more general purpose one? Microstepping might be a bit much to
>> add.
>
>Not practical at all. 
>
>> There was a site that showed using the boards and motors from a pair of
>> floppy drives to build a robot, but it vanished.
>
>No wheels there that we can't reinvent if needed. :)
>
>Cheers, Gene
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>My web page:  is up!
>My views 
>

Re: [Emc-users] Cable drive for a gas torch pattern follower?

[cogoman]

On 03/26/2013 01:21 AM, Gregg Eshelman wrote:
>> I am not sure you will see good acceleration. In fact, it is
>> >always
>> >going to be less than 1g. This is because for any faster
>> >acceleration
>> >the strings go slack as the weighs don't fall fast enough.
> No need to go anywhere near that fast because an oxy-acetylene torch or 
> plasma cutter can't cut that fast. This rig is most often used for cutting 
> steel 3/4" thick or thicker.
   Since counter weights are often used on Z axes on servo machines, I 
once decided to calculate how much of a limit the acceleration due to 
gravity would be.  The metric calculations are left for you folks across 
the pond.

Acceleration due to gravity = 16 feet/second/second

After 1 second the velocity can be 16 feet per second

times 60 = 960 feet per minute (I love spreadsheets!)

times 12 = 11520 inches per minute

divide that by two, so half of that force can be applied to your cable = 
5760 inches per minute

HERE'S WHERE I AM MAKING ASSUMPTIONS THAT MAY BE OFF BY A LITTLE.

If I recall properly 1500 inches per minute is a FAST servo system.

1500/5760 = .26 ( assuming linear acceleration it should only take .26 
seconds to reach 1500 IPM)

1500/60 = 25 inches per second

at 25 inches per second that servo system would travel 6.5 inches at 
full speed while the gravity system would be accelerating to 1500 IPM. 
Of course the servo system wouldn't be able to accelerate 
instantaneously, so the counter weight would only slow a 1500 IPM servo 
system down a little bit.

   I thought gravity would be much more of a limit too.

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Re: [Emc-users] potrace output to scalable gcode. Exists?

[cogoman]

On 03/23/2013 09:51 PM, Gene Heskett wrote:
> All of these seem to need way more memory to work without an OOM tummy
> ache, on either the mill with 2G dram, or on this box with 4G dram.  PyCAM
> just took an OOM exit after running this machine 850 megs into swap, so
> this box is crawling on its belly.
   Though I haven't gotten gcode from pycam myself (yet), from the 
videos I've seen, when you set it up to output milling gcode, it does 
the silly raster scan thing.  When I saw someone doing what I would want 
(2.5 D) they were setting the menus for engraving, and it still did 
gcode for muliple passes cutting an outline.

   If you're already there, you don't need this, but maybe it will help 
someone. Of course maybe I'm wrong, and can be corrected.  I'd like to 
become proficient in openscad->pycam->linuxcnc, and eventually blender-> 
pycam->linuxcnc.

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Re: [Emc-users] Trim Posts

[cogoman]

On 02/18/2013 12:13 PM, John Kasunich wrote:
> If you are trimming your posts, you are also trimming the ads.
> It took me about three seconds to click my mouse near the top
> of this message (after the part I wanted to keep), drag it
> to the bottom, and hit the delete key.
I'm using Thunderbird 17.0.2, and if I highlight the text I want to 
reply to, the reply contains only the highlighted text, and leaves 
everything else out.

   It's quick, it"s easy, and it looks MUCH nicer!  8-)

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[Emc-users] Regarding OpenSCAD

[Cogoman]

>From a post on hackaday I got the impression OpenSCAD might be just what I 
>need to generate G-CODE, but I find more information on 3-D printing G-CODE 
>than routing.
   Am I suppose to export my project as a DXF, and then use DXF2GCODE, or is 
there another way usually used to get G-CODE for a router?
Sent from my Kyocera Rise

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Re: [Emc-users] Using 'clock' spring for dust cover on ball screw

[Cogoman]

If it's worth the hassle to. Reshape the spring, I can picture wrapping it 
around a ceramic rod spiraling. Then using 3 propane torches. Attached to point 
toward the assembly from 120 degrees apart gradually move them from one end of 
the assembly to the other, slowly enough to get the metal cherry red, while 
quenching the red end in water or oil.

 You'll probably have to borrow a torch or two, and perhaps wood could be used 
instead of ceramic if there's enough water to put out the flames.  8-)
Sent from my Kyocera Rise

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Re: [Emc-users] Seasons Greetings

[cogoman]

God Bless us, everyone!

And Merry Christmas to y'all.

Carl

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Re: [Emc-users] LinuxCNC documentation in russian

[cogoman]

On 12/15/2012 04:23 PM, Ben Potter wrote:
> I've got a machine with much the same limit (1200 line) - which is somewhat
> frustrating at times. I couldn't figure out a way to (easily and cheaply)
> convert it over to linuxcnc without replacing the existing drives and
> resolvers - which made it a rather more time consuming and expensive task
> than I was willing to undertake. Oddly enough, there was a post from Tim
> James earlier today about a conversion chip which looks like it may allow me
> to use the original resolvers - bringing the pain of conversion down to
> tolerable levels. The other option would be to upgrade the controller to a
> TNC 151 or 155 - but they seem to be rather rare these days.
   One option on the wiki (but well hidden) is a 3 channel resolver to 
quadrature converter using an arduino and a power op-amp.  It uses a 
2KHz excitation frequency, while the Pico Systems board can use up to 
10KHz. The Pico board goes up to 6RPM, while the arduino probably 
can't go near that.  Still if it can handle 6000 RPM that would be 
pretty good. The Pico board gives 4096 counts per revolution versus 1024 
for the arduino.  The aduino can serve 3 channels at one time.  If the 
new 32 bit arm arduino can do the same sort of thing, it should be able 
to keep up with a 10KHz excitation signal, but that would require a 
significant amount of dev time.
   Here is a link to the wiki entry.

http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ResolverToQuadratureConverter

   I found it by searching yahoo with:

site:linuxcnc.org arduino

   and then looking for resolver to quadrature converter.

   If you decide to try this, you might try breadboarding the circuit 
using the ardweeny from the makershed

http://www.makershed.com/product_p/mksb012.htm

and the lm272, but you would probably save in the long run by just 
building it the way the wiki page shows.

* thanks Andy for the documentation on this! *


   As to the motherboards, I was just referring to how a motherboard 
that many find works extremely well, sometimes doesn't work well for 
another.  I would expect a reasonable choice of motherboards with 2 
different models should be guaranteed to get one that will work well for 
LinuxCNC.
   I've heard of Monday and Friday cars.  I wonder if there are Monday 
and Friday electronics.  I was looking at some android cell phones that 
my wife and I are getting, and when I sorted the comments by date, the 
people who commented Dec 10 of this year seemed to have phones that 
locked up often.  Going back just 3 days from that and everybody seems 
to be gushing about how good they are.  I hope we don't get Monday or 
Friday phones!


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Re: [Emc-users] LinuxCNC documentation in russian

[cogoman]

On 12/15/2012 02:14 PM, andy pugh wrote:
>> when I want to build (or also keep) up a business I have to be reliable
>> >for the customers and grant continuity for my products.
> There is an argument that because_any_  programmer can
> support/fix/modify LinuxCNC that it is more supportable in the long
> term.
>
> If Fanuc closed down, how would Fanuc users get software fixes?
>
> I am not sure that the argument is 100% valid, though.
The previous argument follows the logic of corporate culture that used 
to say "Nobody ever lost their job buying IBM." Until IBM had a bad 
business decision with their spec on CMI hard drives that spawned things 
like CMI reef, a bunch of CMI hard drives dropped in the bay off Boca 
Raton Florida.  The company selling replacement drives advertised it's 
not "IF" your hard drive will die, it's "WHEN" your hard drive dies.  
Suddenly options other than IBM started to make sense.

   From everything I read at the time, it seemed like all of CMI's other 
hard drives were pretty reliable.

   I work with a CNC machine that uses an old Bandit controller. Even 
though it doesn't do any heavy lifting (all 2d work), sometimes we 
overflow the 512 program commands allowed (X1. Y2.  counts as 2).  I 
think that an old machine with reliable axes and spindle would be much 
more useable with LinuxCNC than with a program limit of 512 commands!  
Right though, that you would want to select a motherboard that's 
reliable. Trying 2 MBs to get 1 good one wouldn't be all that expensive 
for a production environment.

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Re: [Emc-users] LinuxCNC documentation in russian

[cogoman]

On 12/13/2012 02:29 PM, Viesturs Lācis wrote:
> But my initial question was about documentation so that I could give
> the guy something to read and then he would ask me questions rather
> than I try to figure out, what is the best way to start explaining
> things.
I was surprised that most "babelfish" translators don't speak Russian.  
I eventually found a link to a babelfish.yahoo.com, which linked me to a 
Micro$oft version of babelfish that will translate a web page to Russian.

http://www.microsofttranslator.com/bv.aspx?from=en&to=ru&a=http://linuxcnc.org/docs/html/quickstart/stepper_quickstart.html


   I realize many of the technical terms will be left out or translated 
incorrectly, but sometimes it's enough for someone to "get the gist of 
it".  I found a web site that had a page on a certain class "A" 
amplifier.  The page was in French, and when the page referenced the 
"power supply" it came back in english as "it's food".  A strange 
translation, but still communicates what the guy was talking about.

   Though not perfect, babelfish might be just what you need for now.


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Re: [Emc-users] Thoughts on an electronic fuse

[cogoman]

On 12/14/2012 03:12 AM, Gene Heskett wrote:
> And I screwed that royally, its 185mv/A, not .185mv.  Way too late.  Or too
> early...
That's ok, it's late here, and I misread .185mV to be 185mV!  8-)

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Re: [Emc-users] concrete table

[cogoman]

On 12/11/2012 11:35 AM, Ralph Stirling wrote:
>There have been entire machines
> built of concrete so you might just look into rebuilding your mill.
>
> (https://www.google.com/search?q=concrete+lathe)
Why do lathes have all the fun?  Where are the concrete 3 axis machines?

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Re: [Emc-users] off topic - device info needed

[cogoman]

On 11/26/2012 03:13 PM, Ralph Stirling wrote:
> Get a real power supply with a transformer, rectifier,
> and capacitor.
If you have switching stepper drivers that have *a capacitor across the 
DC input*, you may be able to use the power supply from an old 20 to 50 
watt per channel stereo amplifier.  With everything going to 5.1 or 7.1 
for video, there are lots of older class AB stereo amps languishing in 
closets.  A typical 30 Watts Per Channel amplifier will have a bipolar 
supply of around 30-35 volts. Taken from +rail to -rail gets you 60-70 
volts.

   My example steppers are from Home Shop CNC.  Their 567 oz-in steppers 
draw 5A at 2.5V per phase.  That's 12.5 watts per phase, or 25 watts per 
motor.  that would be 75 watts average for a typical 3 axis router.  A 
30 Watts Per Channel amplifier should have a power supply capable of 60 
watts average output, since class AB amps are relatively inefficient, so 
while it's outputting 30 watts RMS on two channels (60 watts output) the 
power supply should be providing more like 120 watts.  That should be 
able to handle the 75 watts with a little ineficiency, but if you found 
a 50 Watts Per Channel amplifier, the power supply should have plenty of 
reserve.  The best part is, people would be willing to give it away for 
a good cause!
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Re: [Emc-users] power supplies

[cogoman]

On 11/20/2012 11:28 AM, Gene Heskett wrote:
> But I wanted something at about 40 volts for the lathe & wound up making an
> unregulated linear for 10% of the cost of a switcher at the time.  Loaded
> up, its doing about 37 volts so I missed my target, but it gets the job
> done, moving the lathe at very good speeds.  The linear runs hotter, but
> both are working well.
A little trick that just might get you to that 40 volts.

 1. Find out what the max input current of the power supply is.
 2. find a wall wart 5 volt transformer that puts out 5 volts at the
current specified in step 1 (it must be a linear wall wart).
 3. Wire the primary of the wall wart to your AC in.
 4. Wire the secondary of the wall wart between one side of the AC
input, and one side of the power suply transformer primary.  The
goal is to have the 5 volts AC boost the line voltage to the main
transformer by a marginal amount, and increase the output DC
voltage.  If the output DC voltage gets lowered, simply reverse the
leads on the 5 volt transformer secondary.

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Re: [Emc-users] Using GPU horsepower, was Re: What should I do to get the performance back?

[cogoman]

On 10/26/2012 02:47 PM, John Stewart wrote:
> OpenCL on Linux is ok. At least it was last time I tried it. I started a blog 
> on some stuff I did OpenCL wise:
>
> http://gpucomputes.blogspot.com
>
> (It was set up not as a technical treatise, but for students) (oh, and I ran 
> the code on OSX for the blog, but the code does/did run on Linux)
   I don't mean to try to make work for someone else (my C skills are 
modest at best), but could this be the opportunity to try to break out 
of the one line look ahead limitation?  OpenCL program reads a bunch of 
lines ahead, and maps out the best trajectory for the path to keep the 
tool moving quickly, then lets the real time software know how fast it 
can step through the result.

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Re: [Emc-users] What should I do to get the performance back?

[cogoman]

On 10/26/2012 12:36 PM, Charles Steinkuehler wrote:
> The catch will be to see what the latency numbers look like (I don't
> have hardware in-hand to play with yet, I'm waiting to see if my TI
> rep will get me one of these:http://www.ti.com/tool/tmdssk3358#3  or
> if I'll have to buy it myself).
It looks like it could be usable for LinuxCNC, but are they kidding 
about using it as a thermostat?  $199 for a smart thermostat, and you 
still have to add temperature sensing AND the switch to drive the 
heating system.  Seems link TI doesn't know what applications this thing 
would really be good for.

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Re: [Emc-users] Stupid LinuxCNC Tricks

[cogoman]

On 10/23/2012 11:54 PM, Sebastian Kuzminsky wrote:
> Cool Charles!
>
> I'd love to see your config added to the sample configs we distribute

Ditto to that!  I'd like to see this become commonplace!

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Re: [Emc-users] subroutines and run from line

[cogoman]

On 10/20/2012 04:18 PM, Jon Elson wrote:
> If I select the line with the G01 move,
> and do run from line, it performs that move, but never executes the
> subroutine.
> It sits there in some in-between state, forever.
   I'm just throwing something in here with very limited knowledge of 
what's going on, but if "Run from line" can't see the subroutine (I make 
my very first assumption here, that the sub in in the main program), if 
you were to break the subroutine out to a separate file, would LinuxCNC 
see it there?  Perhaps a work around?

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Re: [Emc-users] Crowdsourced mass CNC produced private weapons

[cogoman]

On 10/18/2012 02:53 PM, Mark Cason wrote:
>Yes, and you will have to be connected to the internet, or it won't
> work.:-)
   And this FEATURE assures that no one can have a trade secret, because 
you are compelled by law to share your designs.

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Re: [Emc-users] Crowdsourced mass CNC produced private weapons

[cogoman]

On 10/18/2012 02:30 PM, Dave wrote:
> A patent is only good if you can enforce it.   If not, it is worthless.
Not necessarily.  If something like this gets in the way of honest 
people, but is easily circumvented by the crafty, then it has strong 
NEGATIVE worth.

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Re: [Emc-users] Gluing little balls

[cogoman]

Brainstorming, but not coming up with what you asked for.  I still think 
one of these ideas might help, so here they are.

   I pictured using a key-hole tool to make the hole in the top surface 
of the wood about 5.8mm for a 6mm ball, then 6mm from about .2mm below 
the surface down to 3.2mm below the surface. Pressure should get the 
ball in tight.  Pressure through the hole in back should push the ball 
back out.  the surface behind being a cylinder shape instead of a sphere 
shape might not significantly affect the appearance.

   If going with the sphere shaped recess, glus could be applied with 
4.5mm dia. tubing dipped in the glue of your choice, and then pressed 
against the spherical hole.  the glue would clear a 2mm thru hole, but 
perhaps not show through the top.  If the tubing is spring loaded in the 
Z axis, Z tolerance against the wood could be near 0.5mm.

On 10/09/2012 08:25 AM, Roland Jollivet wrote:
> I am making small decorative personal gifts using thin wood
> > >>(5-6mm - 1/4
> > >>inch thick) and 6mm diameter colored glass balls (small
> > >>marbles).
> > >>
> > >>A pattern of shaped holes is cut in the wood with a small
> > >>cnc router
> > >>using 2 tools.  A 1/4 ball nose mill cuts to
> > >>approximately 4mm depth.  A
> > >>3/16 tool then cuts the rest of the way through he wood.
> > >>additional
> > >>surface patterns may also be cut.
> > >>
> > >>The balls are then glued into the holes with a clear
> > >>adhesive (
> > >>currently a thinned clear caulking compound).


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[Emc-users] New Linux file system

[cogoman]

   I spotted on slashdot an item about Samsung creating a new file 
system for Linux 'F2FS'.  It is specifically designed to work well with 
solid state flash disks "such as SSD, eMMC, and SD cards".  I know some 
of you have used CF for your storage systems.  Hopefully in the near 
future, instead of tweaking a bunch of settings to keep the file system 
from unnecessarily wearing you flash memory out, you'll just have to 
select F2FS at format time!

   I was looking for the mention of it being an open standard in the 
articles I looked at, but they only hint at it.

http://www.muktware.com/4485/samsung-creates-new-file-system-f2fs-linux-good-news-android#.UG9xo1bMaJd


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Re: [Emc-users] Helical interpolation not quite round, WTF?

[cogoman]

On 09/27/2012 11:19 AM, Dave wrote:
> The first question you always ask, is there a power on light on the
> front of the controller, and what color is it?  That way they look to
> make sure it is actually on.   The power on indicator lights were always
> green, but they don't know that.
What a gracious way of leading them to the solution.

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Re: [Emc-users] Helical interpolation not quite round, WTF?

[cogoman]

On 09/27/2012 09:41 AM, Dave Caroline wrote:
> I would work better if you switch it on!
There is someone at work who has done it to me so often that the first 
thing I say to her is "Did you plug it in? Did you turn it on?"

   One day she came to me and said something like "The computer's stuck 
in DOS.  Fix it!"

   Did you plug it in? Did you turn it on? I asked.

   "Yes I plugged it in and turned it on!" She confidently affirmed.

   I went to check it out.  She hadn't read the screen which cryptically 
said that there was no video signal.

   Text, not a wallpaper, looked like DOS to her.  The old AT style 
computer had just been replaced with an ATX style computer at the same 
station.  I went back and told her I just turned it on (and told her 
where to do it herself).  She HAD turned on the power strip associated 
with that system.



   I used to program GenRad in circuit testers, and the language allowed 
you to use any base for a number you wanted.

b'10110111'   o'267'   and   x'b7'

all represented the same number.  The gotcha for me was that if you left 
the base designation out, it took the number to represent a pin on the 
device you were testing.

If I said addr=2  instead of addr=d'2'  the software would 
dutifully look to see what value was on pin 2, and apply that value to 
the address bus (inserting as many preceeding zeros as necessary).

   That one bit me regularly, and all too often.

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Re: [Emc-users] 100 watt 3 phase AC servo amplifier?

[cogoman]

On 09/23/2012 03:57 PM, andy pugh wrote:
> Indeed, using the actual Hall sensors is much better, I was just
> saying that if the motor does not provide the signals then it is not
> necessarily a complete show-stopper.
   Remembering an article in Machine Design about the CUI AMT303 
commutating encoder made it seem like a good choice for adding U/V/W 
signals to a BLDC motor that doesn't have hall sensors until I saw the 
price.  Digi-key has them for nearly $100.  A bit too high, but these 
are really nice devices.  To align them with your motor, you just 
energize one phase with + volts, another phase with - volts, and leave 
the third disconnected; then toggle the Zero Position pin, and it sets 
the commutation angle to the motor.

   It's a nice technology, but since a similar (but slower) version is 
used in the digital callipers that Harbor Freight makes available for 
$12 with a coupon, I'd say the price is a little out of range.

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Re: [Emc-users] Counting and saving to file

[cogoman]

On 09/15/2012 06:17 AM, andy pugh wrote:
> That is what CSV is, "comma separated variables". The special
> character is a comma.
> It is also a really bad choice, as a large proportion of the world use
> the comma as a decimals separator.
I used to think it meant "comma separated values", and I think that 
makes sense, except that somebody already thought of the usefulness of 
the comma in data.  I just imported something like this file:

fname:lname:stuff:number
erastmus b.:dragging:techie:29
budd:tugly:makeup artist:22

into Libre Office Calc and the import feature allows a radio button 
choice of comma, semi-colon, and a few others, but allows you to choose 
practically ANY character you want to be the separator.  It wants to 
have text surrounded by either single or double quote characters.  I did 
a copy of the file with the colon replaced by the underscore character, 
and it imported fine also.

   While you could use Libre Office to import the CSV file, and write it 
out to an XLS file, I suspect that is not necessary.  While I don't have 
a copy of Excel here to try it out, I suspect it allows semi-colon as a 
separator, and perhaps any other character.  We have imported CSV files 
at work in the past.  Someone wrote an app that takes data from our 
tester and writes it out as a CSV.  We have an Excel spreadsheet that 
takes that data, and puts it into a nice, formatted data sheet we can 
send to customers.

   This probably comes under the heading of Just Works (tm).  8-)

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Re: [Emc-users] For anybody considering upgrading their motherboard in the next few months.

[cogoman]

On 09/15/2012 01:26 AM, Przemek Klosowski wrote:
> If there will be a well-designed and/or inexpensive hardware with this
> chipset, it'll likely get reverse-engineered.
   Years ago I worked on an in-circuit test for a device called a bus 
monitor chip.  It was supposed to be able to monitor memory and IO read 
and writes, and store a count of accesses to a certain address, or just 
look for and access in a certain range, and store it and generate an 
interrupt.  The chip hadn't gotten to the point where it had full data 
sheet functionality, but in theory would have made watching to see how 
the other operating system did things a lot easier.

   These days, I would guess that all that could be put into an FPGA and 
designed into a PCIX card.  Could probably even have a serial port to a 
terminal to let another computer log all the interesting memory 
accesses.  If it came time to pull the gloves off, I'd bet there are 
plenty of Linux guys (and girls) out there who would be able to figure 
out the hardware that way.  Intel might not care if independently a 
Linux distro came out designed for those devices, as long as they had 
nothing to do with it..

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Re: [Emc-users] Counting and saving to file

[cogoman]

On 09/14/2012 03:53 PM, Stephen Dubovsky wrote:
> Python can make database calls.  Just write the lengths to a database.
>   Use database tools to do all the analysis like histogramming, etc.
> Thats what they are very good at.
Or, if the end user is handy with a spreadsheet, you could write it out 
to a .CSV file, and include the date and time so they could tell if data 
came before or after the power failure.  Of course for safety sake, you 
could close the file after each board is stored.

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Re: [Emc-users] moglice, another note

[cogoman]

On 08/26/2012 07:29 PM, jeremy youngs wrote:
>   I am thinking about lining my ways with this product any
> thoughts?
Tormach has a nice whitepaper about the design of their PCNC1100 that 
has me salivating to get one for myself.  In it they have this quote:

"There is a problem with it, however. PTFE is subject to a phenomenon 
known as cold flow."

Go to this link to find out about this, and other stuff that may help 
you avoid a mistake in the future.


http://www.tormach.com/engineering_pcnc1100.html


I was surprised to read that early machines had brass strips over 
hardwood for the ways!

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Re: [Emc-users] Final user of EMC2.

[cogoman]

On 08/15/2012 09:26 PM, a...@conceptmachinery.com wrote:
> I think problem again here.
> I am not talking about UBUNTU.
> I am talking about EMC2 2.2.5 and problem in DELETE file -program name-
> from icon on EMC2 where one load new program.
> When load file/program into EMC2 --EMC2 2.2.5 in my particular
> case---DELETE those file name.
> Is is clear now what i am talking about?
   LinuxCNC (formerly EMC2) without Ubuntu, or without the real time 
kernal, would make your PC just an expensive paperweight.  Ubuntu is the 
operating system on the live CD.
   There is a method for deleting files in Ubuntu, and this youtube 
video (and maybe the ones that follow it) should show how it's done.

http://www.youtube.com/watch?v=Mg1fwIaxDOA


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Re: [Emc-users] file sharing

[cogoman]

On 08/11/2012 09:09 AM, jeremy youngs wrote:
>   I also
> being the owner and moderator If we wanted to set it up here would
> give all the files freely to the organization.
   I don't intend this in a mean way, but if you agree to a license, you 
are bound by that license.  There was a woman who found that out the 
hard way.  She was on a plane when the space shuttle broke through the 
clouds, and she snapped a picture of it with her cell phone, and stored 
it with her twitter account.

   It became a hot item for news outlets all over the country, but she 
couldn't sell it to them... because twitters license agreement let them 
sell the pictures for her, without compensation to her.

http://www.pbs.org/mediashift/2011/06/who-really-owns-your-photos-in-social-media157.html

By the time you decide you want to give the files back to the group, 
you legally can't, because you no longer own them.

   I've read license agreements that most people just click through. 
Craig's list used to, and may still, have a really bad gotcha about 
spam.  If Craig ever got in financial trouble, all he would have to do 
is look for someone on his list that is sending out spam emails, and 
collect $25 for each spam email sent.  If nobody ACTUALLY sent any spam 
through Craig's list it would be no problem.  According to the license 
agreement everybody agreed to, if Craig says your EMAIL is spam, then 
legally your EMAIL is spam.  Craig gets to be the final and legal judge 
about what constitutes spam.

   Most people agree a court might not allow the agreement as stated, 
but if the court considered themselves bound by the letter of the law, 
they would have to.  Also, if Craig wanted to stay in business, he 
wouldn't want to anger his customers, but if he got in a desperate 
financial situation, such an action is a remote possibility.

   I also read one once that was funny.  There was a web site, I believe 
it was called felon-watch.  On the surface it appeared to be a site 
where you type in your address, and it would list the convicted felons 
in your area, and the addresses of where they lived.

   It turned out it was a joke site, probably more intending to make 
people understand the seriousness of the license agreements they click 
through than anything else.  The license agreement said something like this:

   "In order to use this site, you must be greater than 86 years old, 
and have a hippopotamus in your living room.  Further..."   (not really 
quoted, but paraphrased)

   Now I wish I had copied and pasted that license agreement into a 
document, because it was long, and hysterically funny!  All the people 
at work were upset at all the bad guys living in their neighborhoods 
until I pointed the license agreement out!  One person actually asked me 
why I was reading the license agreement, and suggested I just click 
through it to get to the good part.

   License agreements are a pain, but they're here to stay.
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Re: [Emc-users] HAL driver for EMIS Stepper - Board

[cogoman]

On 08/08/2012 01:50 AM, Peter Blodow wrote:
> The only problem is that speed is very limited to about 3.5 kHz max.
> which keeps the machine slow. So, after about 15 years of service, I am
> looking for a more modern board with a little more power (esp. in
> voltage). Thanks for the hints.
   When stepper speed is the issue, the inductance of the stepper 
windings, and resonance control are the two biggest issues.  It still 
amazes me that companies that have a range of steppers based on one 
frame list inductances from about 1.7mH on out to about 45mH.  With sub 
2mH coils, one can get pretty quick performance, when you get out above 
25mH any decent latency test results won't be the speed limiter.

http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Stepper_Motor_Speed_Limitations

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Re: [Emc-users] HAL driver for EMIS Stepper - Board

[cogoman]

On 08/07/2012 05:01 PM, Alexander Grill wrote:
> Unfortunately I don't have a Step-Direction based card installed (I plan
> to build a new one based on TB6560 or A3977, but that is rather a long
> term goal). In the mean time, i want to use my old card (EMIS SMC-800),
> which cannot be driven directly by linuxcnc.
   From what I read, this card is only capable of driving a maximum of 
800mA.  I don't know if you can order from these guys from where you 
are, but for anything under 2.0A these look like a good buy:

http://www.pololu.com/catalog/product/1182

   I believe the step generators (in the right mode) in LinuxCNC can 
drive the phase inputs of this type of board in full step easily, but I 
haven't looked into any modes that use more than 2 pins to add current 
control to the mix.

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Re: [Emc-users] STOP RIGHT NOW...

[cogoman]

On 08/07/2012 02:58 AM, Kirk Wallace wrote:
> If Mach comes up or can provide insight, I think anyone has the right to
> defend or explore it here on the list, especially if one has first hand
> experience with it. LinuxCNC users should be as open (minded) as the
> software.
   I second this motion!

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Re: [Emc-users] solder paste

[cogoman]

On 08/07/2012 08:42 AM, ceen...@in-front.com wrote:
>The majority of boards I run are double sided so all SMT processes are 
> performed twice.  This is one of the reasons I would like a paste printer 
> because the manual stencil printer requires a lot of adjusting and fixturing 
> changes when I go from side 1 (flat, no parts) to side 2 with lumpy parts on 
> the back side.  It would be better if I actually made fixtures for each type 
> of board but where does the time go.
   Sound like you need a plate with a grid of threaded holes, and a 
bunch of (for the lack of a better descriptive term) standoffs.  All 
standoffs would have the bottom threaded to screw into the plate, but 
with a flat at the edge of the threads for an accurate surface 
reference.  There would be a length (I suspect about 1/2 to 3/4 inch 
would be about right) of shaft before the flat at the top for reference 
to the bottom of the board.  Some would then extend in a pin shape that 
fits through your board and your stencil.  You could set up the two 
corners for reference.  You could set up four or more without pins that 
would contact the board at a place where no components would be when you 
flip the board.  They would establish the Z level of the board for both 
screening operations.

   Like the Gecko says " Just a thought.  Right off the top of me head!"

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Re: [Emc-users] solder paste

[cogoman]

On 08/06/2012 09:49 PM, Jon Elson wrote:
> I make my own stencils for these.  It is kind of a pain, but I'm CHEAP!
How about the cheapest CNC to build, an XY plotter like this:

https://www.youtube.com/watch?v=WyLPpGdfR7s

but with the laser from an old DVD burner for the pen.  You could 
produce plotter output files and convert them to G-code, and then cut 
them out of thin plastic (just shield your eyes while it runs, or box it in.

   Getting the tool set in line would take some time, but once you get 
the hang of it, it would save time in the long run.

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Re: [Emc-users] STOP RIGHT NOW...

[cogoman]

On 08/04/2012 07:11 PM, Ron Ginger wrote:
> Mach4, as it will ship, has only been underway since the first of this
> year, and was demoed at the CNC workshop in June. It is intended the
> first version, Mach-lite, will ship in September. I am working on the
> Newfangled wizards for it and they are nearly ready.
>
> All work is being done with cross platform tools, and OEM versions will
> be offered on linux and Mac. That was also shown at the workshop. Next
> chance to see it will be IMTS in September.

   When the Motorola 68K and PowerPC chips continued losing ground to 
the X86 line, Apple found a way to get on the winning hardware while 
still being Apple.

   I don't know how hard it is for Mach to work with newer versions of 
Windows, but I like the cross platform development tools idea. It's 
cheap (though I don't know how cheap) insurance.

   I personally like LinuxCNC, but I'm glad Mach is out there for all 
those who love it, or just use it without knowing.  JustWorks (TM) is 
great, and a few gotchas are to be expected from something as complex as 
a machine controller.  I wish you all the best, Ron.

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[Emc-users] .9 degree vs. 1.8 degree stepper used in RepRap

[cogoman]

   I was looking up something and came across a thread from a gent in 
Australia who was wondering if he could buy .9 degree steppers for his 
RepRap and get them to work, and one guy commented on stepper torque 
with a half truth for the situation.  Apparently the norm for RepRap is 
200 steps per rev at 1/16th stepping, and he was checking out going with 
400 steps per rev at 1/8th stepping.

   I was hoping you'all could check my work before I put in their 
forum.  So,... without further ado...




That is a common misconception. If you set the current on a 
micro-stepping driver to give the same power dissipation you get the 
same torque. I.e. set the single coil on current to 1.4 times the two 
coil on rating.



This is somewhat true, but not for the case presented. With a bi-polar 
motor, when running both coils at the same current in full step mode you 
/are/ limited to .707X amps. When you go to 1/2 step with .707X amps 
driving both coils, the next step will have one coil at 1.0X amps, and 
your 1/2 step torque will be roughly the same.

Now the trouble comes when you use 1/4 stepping. If you raise the single 
coil current to 1.414X, you will degauss the magnets, or burn up the 
windings or both. If you keep the current set to .707X amps, your next 
step will be (according to the table in the A4988 data sheet) either:

from 70.71% to 92.39%

OR

from 70.71% to 38.27%

this will be a change of .217 amps OR .324 amps. If you ran the motor 
full step at less than 1/3 the current it was designed for, would you 
not get less torque out of it?

At 1/16 stepping the current changes in increments of:

100% to 99.52% to 98.08% to 95.69% to 92.39% to 88.19% to 83.15% to 
77.3% to 70.71% ... to 9.80% to 0%

I believe the biggest change in current here is from less than 10% to 
0%. How much torque would you get running the motor full step at 10% of 
the rated current?

You don't have to do the math if you Google up the answer. Search for 
"micro-step torque" and you can come across this link:

http://machinedesign.com/article/microstepping-myths-1009

This article lists the torque available from full step to 1/256 step torque.

100.00% 70.71% 38.27% 19.51% 9.80% 4.91% 2.45% 1.23% 0.61%

   He doesn't take into account that the single coil driven current can 
be 1.414 times the both coils driven equally current, so you can 
multiply the lower torques by 1.414 to get:

100% 100% 54.11% 27.59% 13.85% 6.94% 3.46% 1.74% .86%

   This still shows that your CURRENT-PER-STEP drops when you go beyond 
1/2 step, and is significantly lower at 1/8 step. At 1/16 step, this 
loss of torque is very serious for a milling machine or a router. For a 
filament deposition 3d printer it's probably noticeable, but not very 
serious.

The problem presented here begs to have the difference between full 
step and micro-stepping put into perspective. Let's take an example of 
the same machine, the same stepper motor, and two different methods of 
getting the same resolution.

Solution 1: run the motor full step, but use a 16 to 1 (backlash free) 
gear ratio to get 16 time the resolution.

Solution 2: run the motor direct drive, and use a 1/16 step stepper driver.

Solution 1 has full torque for every step, while for solution 2 there's 
less than 15% of the full torque available for each step. If there's a 
lot of static friction in solution 2, small movements may require 4 or 6 
steps before the head moves at all. In a typical 3d printer you will 
break out of static friction when movement starts, and the head will 
continue moving while laying down your plastic. While the loss of torque 
with solution 2 fighting against the dynamic friction may keep the head 
behind the commanded position by a few steps, the movement per step 
should be fairly close until an axis turns around. X and Y should be 
pretty close to what you'd expect. Z typically is the opposite. Z 
usually goes from one stable position to another stable position very 
close to it, and sits there for a while. Here solution 1 is the clear 
winner.

Of course with solution 1 you'll have to eliminate any resonances in the 
system, and perhaps put up with a little noise when you're not moving 1 
or 2 steps at a time.


Direct drive with a 400 step motor running 1/8 stepping compared to a 
200 step motor running 1/16 stepping comes out marginally in favor of 
the 400 step motor for the Z axis, and only in favor of the 200 step 
motor if the X and Y axis would excite a resonance at 1/8 stepping which 
doesn't show up at 1/16 stepping. There are mechanical methods to 
eliminate the resonances too.


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Re: [Emc-users] Spindle hooked to dc servo amp

[cogoman]

On 07/17/2012 12:36 PM, Jon Elson wrote:
> I don't use NFS, just sftp, and it works fine and is pretty easy to move
> files around between
> machines.
   Thanks for this tip, Jon.  I have 3 machines here.  The one (Compaq 
with Athlon 64 and obscure A8N-LA motherboard) that has my wife's and my 
EMAIL accounts has Linux Mint (I believe it's 11).  It also has the 
printer attached to it.  Mint 11 seems to be confused as to where it 
wants to take commands from.  To shut down we have to go upper right 
rather than lower left.

   Another one (HP Pavilion Slimline s7600n) had Ubuntu Studio on it, 
but it would drop back to a log in prompt without warning every 1/2 hour 
to 1 hour.  So I put MEPIS 11 on it, and it seems to be very stable.  I 
also like MEPIS.

   The 3rd PC is another Compaq, but with a Sempron.  None of these 
would accept the latest version of LinuxCNC, which I desperately wanted 
because named subroutines could have text names.  In my playing around 
with these I came across a setting in the BIOS that looked suspicious, 
so I flipped the switch, and behold! Ubuntu 10.04 with LinuxCNC 
installed and ran as it should!  It didn't have anything to do with the 
usual dealbreakers, but I'd have to look it up to find out what it was I 
changed.

   Right now I have the MEPIS and Mint PCs on a 2 port USB KVM switch.

*What you helped me with is* that the Mint PC appears to have a card 
reader that only supports SD cards, but not SDHC.  I have a camera that 
has an 8 GIG SDHC card with the photos I need on it, so I had to copy 
them to the MEPIS machine. *Sftp took a little getting use to, very 
little, to know the difference between ls and lls, and as you say, it 
took care of the permissions nicely!*
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Re: [Emc-users] USB badness, was Re: BASE_PERIOD and Intel D525MW boards

[cogoman]

On 07/24/2012 07:08 AM, Kent A. Reed wrote:
> Any thoughts?
   From what I've seen looking into USB 2.0 device programming, the 
transfers are too quick for most (maybe all) microcontrollers to keep up 
with in software, so you are generally tied to DMA transfers on the 
microcontroller side.  FTDI has some chips that eliminate the DMA issue 
for the programmer, but they may do DMA internally.

   There is a mode called 'isosynchronus' where a peripheral negotiates 
a certain amount of transfer for every time USB transfers data.  This 
mode can be used for more reliable data streams.  I suspect that a high 
bandwidth peripheral that has a USB port all to itself will not be as 
problematic as one that contends with a mouse and keyboard for the port.

   I also suspect that the USB connection has a certain period between 
communication events.  A base period that gets lots of real time errors 
from contention with USB*/may/* have much less problems with both faster 
and slower base periods.

   Perhaps when documenting what works, and what doesn't, it would make 
sense to keep track of:

1:USB 1.1 or USB 2.0
2:What is the device?
3:Does it have the port to itself?
4:Is a hub being used?  A hub may complicate the timing.
5:The appropriate part of the log files.
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Re: [Emc-users] Docs/Messages

[cogoman]

On 07/23/2012 10:45 AM, Stuart Stevenson wrote:
> Maybe a debug gui with message tags at various places in the software to
> display the control flow and where the current tag is stopped.
   Are you thinking of a program to comb through the log files looking 
for error messages that we know how to fix?

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Re: [Emc-users] [Off] Ballscrew Support?

[cogoman]

On 07/23/2012 03:05 AM, Jeshua Lacock wrote:
> So I just got a response from my ballscrew vendor. They can supply a 40mm 
> diameter with 40mm pitch (3048 mm long) for a reasonable cost. Less than $1k 
> including shipping and machining.
>
> Looks like that could safely rotate at 977 RPM which would move the ballnut 
> at 1538 IPM (with both ends supported with double bearings spaced apart).


   I have been impressed by the white paper for the PCNC1100, and since 
you're aiming for very high rapids, and since this white paper has some 
very good information, I recommend reading it, and all their white 
papers.  Some of the folks on this list could probably vouch for their 
veracity, I just didn't find any clear errors in their analysis.

http://www.tormach.com/engineering_pcnc1100.html

   I think I'd like to own one of these some day.

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Re: [Emc-users] Absolute linear encoders

[cogoman]

On 07/10/2012 05:57 PM, Peter C. Wallace wrote:

If there is demand, it is probably not a difficult one to write.
>Like a number of other components, the problem is having hardware to
>test with, or someone to do the testing vicariously.

Pretty sure the SSI interface works, but the BISS one requires quite expensive
encoders to test (Renishaw Resolute for example though some IC Haus demo
boards might do)

If someone wants to write/debug such things, but lacks the expensive 
encoders (or the throw away money to buy them), I have a low-res 
solution to the problem.


  I have a spreadsheet (.ods) that demonstrates a way to make reflected 
binary grey code (or at least I think that's what it's called.) The 
spreadsheet generates binary, then uses that to generate the grey code.  
Those are done up as numbers. next to them the conditional formatting to 
make a cell with a 1 in it to be black letters on black background, and 
a cell with a 0 in it be white letters on white background.  Using the 
right dropping resistor the optics from an old mouse should be able to 
transmissively detect a 1 or a 0.  I have included grey code for 2 bits 
on up to 6 bits, but it should be easy to expand for even more bits if 
you desire to. You could print out a page at a time, then insert rows at 
the top so that the next page has some redundancy for lining up and 
taping together.  I you do make a linear encoder, it would be cool to 
see pictures and a write up on the WIKI.




ZZ-GRAY-CODE-STRIPS.ods
Description: application/vnd.oasis.opendocument.spreadsheet
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Re: [Emc-users] Brushless Servo Selection?

[cogoman]

On 06/14/2012 10:33 PM, Jon Elson wrote:
> Thats inch-POUNDS!  16 times inch-Ounces.
> 56 In-Lb is 896 Oz-In, so you have made a mistake.  Also, steppers,
> ESPECIALLY
Thanks.  I don't have an intuitive feeling for N-m measures, so for 
quite a while I have been making this mistake in my head.  I had 
wondered why the motors Keling sells were so popular, but so weak.  Now 
I know better.  8-)

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Re: [Emc-users] quick boot

[cogoman]

I know there is an appeal for a controller that can do wifi and other 
neat things, but just in case this could be the solution you didn't know 
you needed:

http://www.megasquirt.info/

A few years back an open engine controller was designed.  I think this 
is the latest version of it.  The advantage is that ALL the features are 
documented and there is forum help if you're having troubles.  This gets 
you further down the development road quicker.

On 06/12/2012 01:31 PM, Stuart Stevenson wrote:
> Gentlemen,
>This exploration project is to find out if LinuxCNC would be a good base
> for an automotive engine control.


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Re: [Emc-users] Brushless Servo Selection?

[cogoman]

I'm concerned that you are about to make a mistake, and waste a lot of 
money.

   450 Oz-in. steppers are pretty hefty devices.  The mill we use at 
work has servo motors rated for approximately 500 oz-in. maximum, and 
they are expensive to replace.  These have all the grunt we need for a 
lot of heavy milling.  The steppers you have should be able to keep up.  
Steppers lose torque at high speed, but most heavy cutting takes place 
at feed rates that have a stepper motor putting out full torque.
   I followed the link to the Keling website, and the heftiest motor 
they listed was a maximum of 6.3N.m, which I assume (correct me if I'm 
wrong) means Newton-Meters.  The conversion calculator I used gave me 56 
inch pounds, a little more than a tenth of the torque your steppers 
should be able to put out.  If you get outright stalls with 450 inch 
pounds, you will more often get outright stalls with 56 inch pounds.  If 
you are missing steps, it's probably not the motors' faults.  Something 
else is probably at work here.

   The only valid reason I could see for upgrading would be to get 
faster rapids.  If you are trying to drive the steppers faster than they 
can go, you may lose steps, but otherwise you should look at another cause.

   First find the drive voltage, and the coil inductance of the motors. 
With a switching stepper motor controller, 70 volts can get a 1mH coil 
up to 7 amps in about 100uS.if you give it another 100uS to stay at 7 
amps, you can have almost full torque for 200uS per step.  For a full 
stepped standard 200 steps per rev motor that would be 1500 RPM.

   Your motors probably don't have that low inductance. Divide by 2 for 
2mH = 750RPM.  Divide by 3 for 3mH = 500RPM.  That should be plenty to 
keep up with milling at even 50 IPM.  I wouldn't want to go far above 
3mH for something that has to be fast.

   These guys have a NEMA 34 motor with 7A (parallel) coil current at 
1.2mH per coil with nearly 600 oz-in.

http://www.homeshopcnc.com/index.php?page=shop.product_details&flypage=gk_flypage.tpl&product_id=29&category_id=5&option=com_virtuemart&Itemid=1
 


   That would be a pretty fast stepper, with good torque.

   I suspect your problem is either electrical/wiring getting old, or if 
you have a rubber resonance damper in the system, and it has become 
petrified.  Rubber gets old.  you may just need to replace a resonance 
damper, as resonance can drop the torque to 0.0 well before the top RPM 
should occur. If the resonance damper is not too far gone, it could be 
causing seemingly random errors.

   Also 7A is a lot of current.  Dirty connectors can limit that 
current, or at least the speed that current ramps up at.  You could 
connect some wires to a coil on the stepper that's giving you the most 
trouble, and connect it to a DMM,  See if the voltage is what it's 
supposed to be when the motor just comes to a stop.  If the wires are 
hooked up to screw terminals, and that has gotten corroded, a little 
cleaning with Scotch Brite or fine sand paper, and re-tightening may 
solve your problem. Plug in connectors could be tougher to fix.  I hope 
you don't have old wire that needs replacing.

   Of course, if your problem is A: bad wiring or B: a hardened 
resonance damper, or C: too much resistance in the high current wiring 
to the motor;   AND... if you replaced the whole system with an 
expensive servo system with new wiring and no resonance dampers; your 
problem should go away.

   I suspect that if it's a simple problem with the stepper system, a 
simple solution would be just as satisfying.

On 06/13/2012 11:48 AM, Todd Zuercher wrote:
> I am thinking about trying to upgrade some old routers from steppers to
> servos.  I am seeking advice on a good and inexpensive BLDC motor to
> use.
>
> The steppers on them now are NEMA 34 with a 3/8" shaft, rated at 7amp
> and 450 oz-in. and are half stepping from an old Anaheim Automation
> unipolar bi-level drive.
>
> We are tired of lost and missed steps not to mention outright stalls
> ruining pieces.


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Re: [Emc-users] 3D Printer Parts

[cogoman]

On 06/11/2012 11:56 PM, Jeshua Lacock wrote:
>> But that is also a 15V part IIRC.  But that's ok - the only reason the
>> >  Makerbot uses a PC power supply is because they are dirt cheap and TUV
>> >  certified.  You can use any supply you want.  I use 15V supplies.
> OK, that was my main concern. I just don't understand how the Gecko will 
> "know" not to give it more than 5v?
>
Modern stepper motor drivers use the inductance of the stepper motor 
coil to their advantage.  If you turn the 15 DC volts on to your stepper 
motor, the coil current starts out at 0 amps.  A fast motherboard 
parallel port could be issuing a step pulse to the stepper motor 
controller before the fastest stepper I've seen could get to 1 amp from 
a fifteen volt supply.  Check out this link to see how long a typical 
fast stepper motor takes for the current to build up:

http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Stepper_Motor_Speed_Limitations

Most modern stepper motor controllers switch the full voltage on to the 
stepper motor coil, and monitor a series resistor to see what the 
current through the coil is.  When the current through the coil exceeds 
it's set point, the switch is turned off, and the coil goes into 
fast/slow decay mode. It then either waits a preset time, or looks for 
the current to dip below the preset level by a certain amount.

   I don't know the circuitry in the Gecko drives, but they may have a 
low level current source drive current through the current set 
resistor.  I believe that the G540 drives 1 amp for each 1000 ohms of 
set resistor resistance.  It may do that by supplying a fixed current to 
the set resistor, then comparing the voltage across the resistor to the 
voltage across the resistor in series with the motor coil.

   Lets look at a hypothetical situation.  With a 1 ohm coil series 
resistor, and 1mA going through the setpoint resistor, if the setpoint 
resistor was 1.5 Kohms, there would be 1.5 volts across that resistor.  
If you compare the voltage across the coil series resistor, and make it 
match the voltage across the setpoint resistor, then there would be 1.5 
volts across the 1 ohm coil series resistor too.  That would correspond 
to a current level of 1.5 Amps.

   So the circuit would turn on the full 15V to the coil.  When the 
current through the coil reaches 1.5 A (assuming a setpoint resistance 
of 1.5 Kohms) The circuit would turn the voltage off, and let the coil 
current fall for a time, then if it was back below the setpoint, the 
circuit would turn the voltage back on.

   For more than you care to know about driving stepper motors, look up 
"Jones on stepper motors"

http://www.divms.uiowa.edu/~jones/step/ 


   If you use the Gecko, be sure to read the manual about setting the 
current level a few times, so you don't overdrive your motors.



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Re: [Emc-users] Encoder discs

[cogoman]

I reworked the postscript program so you can specify encoder wheel size, 
and index pulse width for an encoder, then you can call the subroutine 
(done twice at the bottom) at different places on the paper.
   Hopefully the instructions in another message for using GIMP can get 
you the resolution you need.

On 06/02/2012 03:58 PM, gene heskett wrote:
> Thanks cogoman.  This would be useful if I had room for a 6" OD wheel, but
> my limit in the space I have is about 2.7" in diameter.
%! Postscript utility for printing multiple encoder wheels

/inch {72 mul} def  % #points/inch (don't change me)
/sizeo 2 inch def   % outside radius of encoder wheel
/sizei 1.8 inch def % inside radius of encoder wedges
/segments 256 def   % number of segments (black and white)
/ipwidth 5.5 def% width of index pulse bar
/moveout 4 def% how far from left side to put encoder wheel
/moveup 4 def% how far from the bottom to put the encoder wheel
/angle 360 segments div def

/wedge
  { /radius exch def
   /angle_s exch def
   /angle_e exch def
   newpath 0 0 moveto
   0 0 radius angle_s angle_e arc
   closepath
  } def

/encoder
{
 % ADD IN THE ENCODER WHEEL AT THE SPECIFIED DIAMETER
 gsave
  0 1 segments {
   360 segments div rotate
   angle 0 sizeo wedge
   2 mod 0 eq {1} {0} ifelse
   setgray fill
  } for
 grestore

 %THIS ROUTINE FILLS THE CENTER WITH WHITE, AND SOMEHOW PUTS A 
SOLID CIRCLE
 %  INSIDE THE GROUP OF WEDGES
 %THIS LINE SPECIFIES WHERE TO PUT THE CENTER

 0 0 sizei 0 360 arc
 gsave
   0 setgray stroke
 grestore
   9 setgray fill

   ipwidth 0 sizei wedge
   0 setgray fill



 %THIS ROUTINE PUTS A TINY DOT IN THE CENTER TO AID IN MOUNTING 
THE DISC
 %THIS LINE SPECIFIES WHERE TO PUT THE CENTER
 0.0 inch 0.0 inch .01 inch 0 360 arc
 gsave
   stroke
 grestore
 0 setgray fill

} def

gsave
 2.5 inch 2.5 inch translate
 encoder
grestore
 2.5 inch 7.5 inch translate
 encoder
showpage


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Re: [Emc-users] Encoder discs

[cogoman]

On 06/02/2012 04:27 PM, cogoman wrote:
> The eps file is vector graphics, it can generate as fine detail as
> you need.
One thing I forgot to mention, with this technique, your printer's 
resolution is the limiting factor, and with modern printers, it's 
usually not very limiting at their highest quality setting.

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Re: [Emc-users] Encoder discs

[cogoman]

   The eps file is vector graphics, it can generate as fine detail as 
you need.

   When I used GIMP to output to .JPG I got very good resolution, but I 
had to ask for it.
Try this:

 1. Right click on the .eps file.
 2. Click on "Open with".
 3. Click on GIMP.
 4. The dialog "Import from PostScript" will default to Resolution: 100
(I believe this is DPI), change it to 600 (or if you have enough
RAM, 1200
 5. Set the "Width:" to your resolution times 8.5 (assuming 8.5 by 11 paper)
 6. Set the "Height:" to your resolution times 11.  I did 600, 8000,
8000 and it took about 2 minutes to import.
 7. Set it to B/W, or, if you want anti aliasing, set it to Gray.
 8. Once imported, you can zoom in and see very good detail.
 9. Save it as .jpg or as .png, or if you can get GIMP to behave while
printing, print it directly


   One hint, try starting at 150 DPI, this should go quickly and you can 
zoom in to see the detail (or lack thereof). You probably won't want to 
save this one.
   Then try importing at 300 DPI, and look at the detail, remembering 
that the time will probably increase with the square of the resolution.  
It quickly becomes long, but you'll probably want a resolution that will 
take minutes to import, and 1/2 minutes for each step in zooming in.


On 06/02/2012 03:58 PM, gene heskett wrote:
> I scaled this down to the size I needed, and added enough to do it 2 up
> which didn't come close to occupying the full 8.5x11 page. I was about to
> add the index track too when I gave up due to poor resolution from the eps
> fixed pixel size.
>
> But when imported into gimp at 72 dpi, the resolution turns it into pretty
> fuzzy stuff, with or without the anti-aliasing turned on.

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[Emc-users] Encoder discs

[cogoman]

   While I can see the need (sometimes) for a durable metal encoder 
disc, and I have cut some out of .016" copper (was on hand, and never 
got tested), I wonder how useful, or how durable laser printed 
transparency film would be for many applications.  Two of them glued 
back to back with the printing on the inside might be reasonably 
durable.  all but the fingers could be clamped between an aluminum 
mounting piece giving some physical stability.  The resolvers on our 
Shizuoka are located in sealed coffee can shaped bins, so reasonably 
protected from swarf.  One could take a .JPG to Staples and have them 
print out a few with whatever resolution you choose (make THEM keep the 
stock of laser transparency film).

   The original encoder code was borrowed by a guy doing robotic 
encoders for some surplus Pittman gearmotors for robotics, though he 
used reflective sensors with less than 30 segments.  I borrowed the code 
from him and made changes to make it easier to center a large encoder 
wheel. I have printed out samples (though I haven't used any yet) and 
get reasonable looking prints with 512 segments or more.  I haven't 
added the index wedge yet, but I will insert the code that I do have here.


%! Postscript utility for printing  an encoder wheel
%
/inch {72 mul} def  % #points/inch (don't change me)
/size 3.9 inch def% radius of encoder wheel
/segments 1024 def% number of segments (black and white)
/angle 360 segments div def
/wedge
  { /radius exch def
   /angle_s exch def
   /angle_e exch def
   newpath 0 0 moveto
   0 0 radius angle_s angle_e arc
   closepath
  } def

% ADD IN THE ENCODER WHEEL AT THE SPECIFIED DIAMETER
gsave
 %THIS LINE SPECIFIES WHERE TO PUT THE CENTER
  4.0 inch 4.0 inch translate
  0 1 segments {
   360 segments div rotate
   angle 0 size wedge
   2 mod 0 eq {1} {0} ifelse
   setgray fill
  } for
grestore

 %THIS ROUTINE FILLS THE CENTER WITH WHITE, AND SOMEHOW PUTS A SOLID 
CIRCLE
 %  INSIDE THE GROUP OF WEDGES
 %THIS LINE SPECIFIES WHERE TO PUT THE CENTER
4.0 inch 4.0 inch 3.0 inch 0 360 arc
gsave
   stroke
grestore
9 setgray fill

 %THIS ROUTINE PUTS A TINY DOT IN THE CENTER TO AID IN MOUNTING THE DISC
 %THIS LINE SPECIFIES WHERE TO PUT THE CENTER
4.0 inch 4.0 inch .01 inch 0 360 arc
gsave
   stroke
grestore
0 setgray fill

showpage


   I open the .eps file in Gimp.  Most Linuxes come with ghostscript 
installed, and that's what Gimp uses to write it out to a .JPG.  To get 
good resolution, you need to print out a lot of dots, and that requires 
a lot of RAM, or a long time swapping to/from available RAM.  I think I 
remember using 8000 by 8000 for the final file size.  If Staples has a 
printer that handles postscript directly, you should be able to size and 
position the disc in the .eps code, and print it directly from .eps with 
much better resolution.  With some care you should be able to get 
multiple encoders per sheet, depending on how big you want them.

   Hopefully this will be useful for someone.  It sure is quicker than 
cutting that ultra thin aluminum, and the segments /should/ be equal in 
size (for 50% duty cycle).

   For test purposes, if you have clear spray paint on hand (Krylon 
works well here) printing on paper will give you the black.  Several 
very light coats of Krylon on the print side will stabilize the print, 
then a heavier coat from the back will soak into the paper and make it 
more transparent.  All the paint should make the disc stiffer, and seal 
it against some moisture.  You could mount the disc in between 
cardboards with a hole cut in the middle to keep it flat while the paint 
dries.

   Does anyone think that this needs to go in the knowledgebase?  I 
searched for encoder and didn't find any references that appeared to 
have this information.
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Re: [Emc-users] Setting coordinate systems

[cogoman]

On 05/19/2012 06:06 AM, Erik Christiansen wrote:
> It scares me that coordinate offsets could be cumulative. Coordinate
> offsets (workspaces) should not nest, I believe. I have not read
> anything in the doco to say that they do.
   That doesn't scare me at all, as long as the documentation is clear.  
On an old Bandit controller I use relative positioning to make multiple 
parts on a sheet.  If I had multiple fixtures, so that I could have a 
relative offset to the fixture, and then within that fixture a relative 
offset for doing multiple parts on the same stock, it would not be a big 
deal IF... it was clearly documented how to do that.  That way I could 
do multiple parts in absolute positioning, which would make my position 
in the part easier to read.

Full Disclosure:  I have not used offsets in LinuxCNC yet.  (except 
where one got set without me knowing it, and I had to zero it out to get 
my desired result.)

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Re: [Emc-users] OT-Retrofitting machines

[cogoman]

On 05/12/2012 10:15 AM, k...@gmail.com wrote:
> There is a bit of talk on some machine shop forums, arguments perhaps, that
> retrofitting a machine is a waste of time.
> And that it's time and money well spent to just buy a good used
> machine and move on with making money with it.
> Any comments on this from the list?
   It seems like some information for making a good comment is missing.  
This decision, although it can be divided up into lots of 
micro-categories, to do it justice needs at least a few categories.  I 
suggest these basic ones.

1.  A machine shop with lots of paying customers, lots of machining 
knowledge, and little electronics knowledge, and no spare time.

2.  Someone with time on their hands, and enough electronic knowledge.
 A. a manual machine that can be bought for a song, and is in 
good condition.
 B. a CNC machine that can be bought for a song, and has a 
control issue.
 C. a CNC machine that can be bought for a song, and requires 
major rebuilding.



   From what I've heard, converting a manual machine to CNC is very 
unlikely to be a good decision, although for some it might work.

   Someone who has lurked in this forum should know enough parts sources 
to make a good decision on parts to replace a control on a machine 
that's in good shape otherwise.

   A CNC machine that's been abused, that has rusted ball screws and 
ways may not be a good choice even if it has a working control.

   I still use a Bandit control at work that's limited to 512 program 
commands.  Even working that is a major limitation for someone who has 
more complicated parts to cut.  For what we use it for, 512 commands is 
rarely a limitation at all; but I would suspect the typical shop would 
want to replace at least the computer part.

   For the machine shop that has lots of expertise in machining, and 
little in electronics, a working machine either new or great used 
condition is just the right match.

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Re: [Emc-users] Electronic damping of stepper mid-band resonance, was Re: Drive Tuning

[cogoman]

I don't see how they could switch from 1/10 to full step without letting 
LinuxCNC know, and having LinuxCNC reduce the number of steps being 
sent, unless they used a clock multiplier, which would make it look like 
full step to the control, and just use microstepping to smooth out the 
full steps.  The full explanation would be fascinating.

On 05/01/2012 03:52 AM, Peter wrote:
> Hi Jon,
>
> Yes, the Geckos are one of the few drives that have electronic
> anti-resonace built it. The other feature that improves the performance is
> that they morph from 1/10 to fullstep as the stepper rpm increases. This
> overcomes the deficiencies of using microstepping at faster rpms, and
> gives you the best of both worlds.


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Re: [Emc-users] the state of the Wiki

[cogoman]

for section 2 Getting Started.

   I have not yet gotten too far with CAD/CAM to generate gcode, but I 
have a suggestion to run up the flagpole to see if anyone salutes.  I 
suggest we select 2 CAD/CAM solutions to include on the CD, with special 
support in the wiki.  One would allow complex things to be done (with 
it's steep learning curve), and one would be simple and easy, so as to 
have a short learning curve.

   I (selfishly) suggest we use blender for the complicated one (since I 
have a project that will require multiple parts to be attached having 
only axes in common).

   I have used GSimple to make some parts, but I recently found that 
LibreOffice Draw allows me to draw to scale.  I have printed out a drill 
guide for center punching the location of holes in an orderly manner on 
a wooden project and the printout was practically to scale.  Though I 
haven't tried it, Draw claims to be able to export to Scaled Vector 
Graphics (.SVG), and in the wiki the CAM plugin for blender is supposed 
to work off of the .SVG file.  PyCAM is supposed to work with .SVG, so 
we might only need to cover instructions on using one CAM solution for 
both the easy and the hard.  These two CAD/CAM solutions would get 
special emphasis on the wiki to get people up and running quicker, and 
these wiki pages would also be included on the CD.

   I know the CD is already nearly full, but I suspect we could make 
room for these, and if not, we could remaster it as a DVD with these 
tools and their necessary tutorials.  Perhaps if a DVD is required, we 
could include video tutorials to further help out.

On 04/27/2012 01:26 PM, Kent A. Reed wrote:
> Section 2.
>
> "Hardware Requirements" needs work to bring it up to current technology,
> both in terms of LinuxCNC and in terms of platforms. Since the following
> subsection "LinuxCNC Supported Hardware" also uses the word "Hardware"
> but in the sense of interfaces, I think it would be useful to choose the
> title "Computer Requirements" instead.
>
> "LinuxCNC Supported Hardware" is probably as good as it gets given the
> flux in the marketplace.
>
> "Latency Test" is a conundrum for me. I can't figure whether it would be
> better to sort it on brandname or on date of the system. Right now the
> table seems a mixture of top posting, bottom posting, and alphabetical
> posting. Still, I wouldn't want to throw the baby out with the bathwater.
   Why not have a few pages with the data sorted different ways, and 
links at the top of the pages so each points to each of the others, and 
the back link of all 3 of 4 pointing back to the wiki main page?

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Re: [Emc-users] Relay driver not working

[cogoman]

On 04/20/2012 06:20 PM, Peter C. Wallace wrote:
> A dozen or so shorted I/O lines is unlikely to cause FPGA damage  (ask
> me how I know)
I can imagine... 5 years from now someone is looking at a LinuxCNC 
configuration using a MESA card and wonders  "Why is he using stepper 
outputs 4, 5 and 6 for X, Y and Z?  Wouldn't 1,2 and 3 make more sense?"

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Re: [Emc-users] Trajectory planning and other topics from a, EMC(LinuxCNC) newbie (TheNewbie)

[cogoman]

I am a bit behind due to trying to get my EMAIL machine upgraded to a 
newer model I received as a hand me down.  The on board video stymied 
every distribution except puppy!  I eventually was given an older PCI-X 
video card that allowed me to install main stream distros, and now I've 
pretty much caught up with this list.

   Now to my comment.  I think stepper motors are getting a bad rap when 
it comes to missed steps.

   Let's say you have a motor capable of putting out 500 oz-In of 
torque, and you are using it with a big dull shell mill.  When the 
machine requires more than the 500 oz-in the motor is capable of putting 
out, the encoder lets you know that you are behind, and the machine 
stops.  Your part may be scrap.

   The thing that is being missed here is that I didn't mention if the 
motor is servo or stepper.  With either technology you still have to 
stop and correct your original problem (put a fresh shell mill in, or 
take a smaller cut.)  The difference is that with a servo motor the 
machine constantly determines what level of oomph the motor needs.  With 
a stepper motor the portion of a full step that the system gets behind 
determines the amount of torque applied to the load.  If either are 
asked to put out more than they can, the system should stop.

On 03/31/2012 03:20 PM, Dave wrote:
> My experience with steppers is that once you lose sync with the rotor at
> speed, you have to slow down tremendously to regain sync with the rotor.
> So once you start slipping, you are pretty much done as you have lost
> control of the motor. I don't see how using encoders with steppers
> really helps other than detecting when you have lost control of the motor.
>
> Dave


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Re: [Emc-users] Trajectory planning and other topics from a, EMC(LinuxCNC) newbie (TheNewbie)

[cogoman]

From: Viesturs L?cis  Subject: Re: [Emc-users]
> This will run in a little off-topic by me...
> You can run heavy duty machines with steppers, but then the
> performance will suffer - You will have to leave big safety margin in
> terms of load to motors (either move slower or use way much larger
> motors) as currently there is no safe and reliable way to recover "on
> the fly" from lost steps.
> Last year I had a discussion with Festo people in Hannouver Messe
> about this topic - they are offering pseido-servo control system,
> which consists of:
> 1) stepper motors
> 2) encoders on motors for feedback
> 3) controller, in which error in feedback loop is fixed in classical
> manner - add throttle, when motor is falling behind
>
> I managed to left their representative without any arguments as this
> approach totally sucks - if the load on motor is large enough for it
> to start losing steps, then there is no sense to increase the RPM - it
> will continue to lose steps.
> It has been proposed on this mailing list that completely new approach
> would required - all the remaining joints should slow down so that the
> one with lost steps remains in the correct place with respect to
> other.
> I guess some special drive, that could increase the current for a
> short time to increase motor torque, would allow to use the classical
> approach, but I will leave that for people, who actually do understand
> something about stepper drives and the principles, how they work.
Seems to me the only way to practically set up a stepper system with 
feedback would be to run linuxcnc as if it were driving servos, but set 
up the stepgen as velocity mode, then when a feedback error occurs 
instead of increasing the velocity signal, it would feed back to the 
slider that controls percentage of commanded rate, and slow down the 
commanded rate, while lighting an obnoxious light on the front panel to 
alert you that you might have a tool that's about to snap.
   I don't know the inner workings well enough to say this is possible, 
but it seems like it should be with linuxcnc, and if someone were to 
implement it and document it, that would be a feather in the cap of 
linuxcnc.

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Re: [Emc-users] steppers

[cogoman]

> Could you give me some idea of what the advantage is of using 2 and 3
> >  stack steppers?
   Perhaps I'm in over my head here, but I'll share what I think I 
know.  The tendency for 2 to 3 stack steppers is for the magnetic 
circuit inside to get too long, and create high inductance for the 
amount of field strength it produces.  This limits the top speed of the 
stepper (the assumption here is standard 200 steps per rev steppers).  
There's a point where stepping up to a NEMA34 from a NEMA23 will get the 
torque needed with less inductance, which allows for more speed.
   This, is more theoretical than practical, since it is quite possible 
to design a slow stepper in both NEMA23 and NEMA34 sizes, and many do 
just that.  While a fast stepper motor needs to have less than 3 mH 
inductance per coil, I have seen even small steppers with over 10 mH.

Rexstep stepper motors 

 
and usa stepper motors  
seem to have low inductance per torque, assuming you can trust their specs.

This one 
, 
and this one 
 
seem to have too much inductance for fast operation.  So practically 
speaking, you need to evaluate each motor separately.

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[Emc-users] pycam

[cogoman]

On 01/03/2012 07:26 AM, matthew venn wrote:
> Hi all,
>
> a few weeks back I asked about turning STL files from openscad to gcode for
> my router. Pycam was suggested and I've been playing with that.
> However the wiki is pretty bare, and the mailing list and archives are
> pretty slim pickings too!
I searched for pycam on youtube (because I saw a video there recently 
that documented g-code generation using open source tools.  I would like 
to become proficient in the Blender->Pycam toolset.  This one may not 
cover your specific questions, but will undoubtedly be helpful for 
someone other than me.

http://www.youtube.com/watch?v=wI7uj-6KgyE

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Re: [Emc-users] Emc-users Digest, Vol 69, Issue 5

[cogoman]

On 01/02/2012 01:46 PM, Kirk Wallace wrote:
> I am hopping for a better 2012 too, and wishing for a speedy recovery to
> all those on the mend.
> -- 
 I second this.  I'll be praying.


 I had to pass on this little advice.  For someone taking any kind 
of prescription drug for anything, check the side effects.  Then, every 
month (with a long term prescription) check them again.  I have two 
stories that illustrate this.

 A guy with terrible tinnitus, for over 3 years his doctor was 
trying to find something to cure his tinnitus.  It got so bad that he 
contacted a homeopathic doctor from Africa for a cure.  The first thing 
this doctor did was to send him a list of medicines known to cause 
tinnitus.  Two of the meds on the list had been prescribed for him for 
years.
 A retired senior lady (you never ask age) had symptoms over about 4 
months including trouble breathing, weakness, rash, itch, mood swings, 
hallucinations, and a few others.  She was originally hospitalized with 
four or five symptoms that could have been caused by the sleeping pills 
that were originally prescribed while at home.  Some other things 
prescribed while in the hospital caused fear, hallucinations, and itch.  
We thought we were going to lose her.  Now that she's off those drugs, 
she's back to normal mentally, and not very itchy.  The only thing she 
hasn't recovered yet is the strength in her arms and legs form atrophy 
lying in the hospital bed.

   Slightly sorry it's off topic, but if it keeps a portion of our brain 
trust here a bit longer, it's worth it.


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Re: [Emc-users] also

[cogoman]

On 12/15/2011 05:35 AM, emc-users-requ...@lists.sourceforge.net wrote:
>> was thinking about this what if one was to attach a synchronus steppe as an 
>> encoder one could under drive it ( incresed sensivity,and resolution), put 
>> current limiting resistors inline (10 k ohm?) and opt isolate to protect 
>> from overvoltage, and the back emf would provied sensor signal, any 
>> thoughts? and maybe an h bridge to clamp low (i.e. braking?) seems like this 
>> would be robust and relatively inexpensive with many benefits thanx jeremy
> nice in theory, in practice you'll face serious magnetic noise in a machine; 
> I tried - not viable for me
>
> you're better off shooting a decent encoder off ebay or so
If you're looking for cheap, you could try having Staples laser 
print on transparency paper your favorite encoder disc from one of those 
encapsulated postscript  encoder files, and reading it with the optics 
from an old mouse with a ball.
   Does anybody think a somewhat universal encoder file in .EPS format 
would make a good addition to the wiki?  I open them up in GIMP, and 
write out a .JPG or .PNG that can be brought into LibreOffice and sized 
to fit your needs (as long as there are enough dots per inch to your 
printer.)  If you try this and you want great resolution (lots of dots), 
and you have an old PC (256MEG of RAM) you WILL need a chunk of swap 
space.  This can make GIMP seem like it's locked up, but as long as you 
have enough swap space it will only take a long time.

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Re: [Emc-users] emc install

[cogoman]

On 12/14/2011 06:59 PM, emc-users-requ...@lists.sourceforge.net wrote:
> hello , bought a dell about 2 months ago, loaded with ubuntu 10.10? realized 
> that wont work with emc, so i downloaded the live cd (from a windows machine) 
> when i put the cd in the dell and try to open it it says it needs to be made 
> bootable (???) i was able to verify the md5 checksum, do i have to format 
> this drive? then install? also the getting started docs say you may have to 
> write a command from dos, or shell? if your bios dont try to boot the disk is 
> this my problem or does it just not want to roll back the version of ubuntu? 
> thanx jeremy
>
> --
>
> Message: 7
> Date: Wed, 14 Dec 2011 15:59:15 -0800
> From: Dan Field
> Subject: Re: [Emc-users] emc install
> To: "Enhanced Machine Controller (EMC)"
>   
> Message-ID:<4ee93853.4000...@roadrunner.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Been a while so there's my disclaimer:  "Live CD" is bootable as I recall.
>
> Leave the "Live CD" in the  CD/dvd drive and reboot. On first load
> screen look at the bottom to findenter setup, usually say F2 but
> depends.
>
> Once in the Bios setup look for "Boot".You want to change the order
> (  with  + or - on the keyboard ) to put the  CD/dvd drive First in Boot
> order.
>
> Save changes on exit
>
> Reboot and it should now look at the CD/dvd drive first.Wait for
> the load and follow instructions.
>
> Remember to change the Boot order back to you Hard Drive when you're all
> done.
   I don't think you need to change back unless you're very security 
conscious.  When there is no CD or DVD in the drive, it will fall back 
to booting the hard drive.  If there is an audio CD in the drive it will 
either see that it is not bootable, and boot from the hard drive, or it 
will only complain until you remove the CD and then boot up.

   One other thing that can get you is that when burning a CD in Windows 
(or Linux for that matter) your PC can offer to make a data disk for 
you, instead of using the ISO file as a disk image.  If you boot up in 
Windows, and put the CD in the drive, then use Windows Explorer to see 
what's on the disk (or, if autorun asks what to do, choose look at files 
and folders in folder view), if you only see one file, and it's 
extension is .ISO, then your PC helped you out by 
making a DATA CD, which is useless for this purpose.  If you find some 
files and some folders, you have probably made a bootable CD.

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[Emc-users] Scopes

[cogoman]

Seems like a zillion years ago, when I was young and dumb, I bought a used 
Phillips PM3212 25MHz triggered sweep dual trace scope from a vendor at the 
Trenton Computer Fair.  I wasn't dumb enough for them though.  They sold it 
without scope leads, so I found some bare copper wire and took it over to one 
of the buildings and plugged it in to check the channels.  The whole thing was 
dead as a doornail.  When I took it back to the vendor, he kindly took back the 
paperweight and gave me another.  He had about 8 of them there for sale.  This 
second one checked out and showed a nice square wave from the 1.2V calibration 
output.
   I don't know how accurate the waveform is, and 25 MHz doesn't sound like 
much, but it's fast enough to measure the speed of light in a small space 
(about 12 inches per nanosecond) and it's fast enough to be useful on most 
waveforms short of microwave.  The main thing is, when you need an 
oscilloscope, you need an oscilloscope.  Sometimes even an old recurrent weep 
dinosaur can save your bacon.

Mark Wendt wrote:

>I recently became the proud papa of a Tektronix
> 7623A O'scope, purchased off the Bay of E.  It's a mainframe storage
> scope, capable of handling three plugins - two vertical amps and a
> horizontal timebase.  I got that machine, a few different plugins, a
> number of probes, and some other odds and ends for less than $500.  It's
> an analog scope, but in it's time, it was one of the high-end scopes
> that Tek made, and it's still going strong even at close to 30 years of
> age.
>
> This one is identical to the one I have:
>
> 
>
> You can get better prices by waiting a bit.  I got mine for $100 plus
> shipping.
>
> A venerable high quality machine that you can use to help troubleshoot
> problems like the ones that showed up in the Encoder thread.


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Re: [Emc-users] Need help with servo tuning

[cogoman]

On 10/07/2011 10:16 PM, emc-users-requ...@lists.sourceforge.net wrote:
> SIG and TAC are attenuators for the velocity command input and the
> tachometer input.
> CLM is current limit.  BAL is the zero offset.  TC is most likely the
> loop compensation
> on either the torque loop or velocity loop.
I was thinking about doing this, and then I find that you've done it, 
Jon.  Still I have to add my 2 cents.

1. input SIGnal gain
2. TAChometer input level
3. Current LiMit set point
4. dc BALance is the dc offset from 0V.
5. TC I'm glad you answered this one, cause I would have had to look 
it up. 8-)

Sometimes knowing what they are abbreviations for can help to remember them.

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[Emc-users] ASCII drawing program

[cogoman]

Thanks Kent, Thanks Przemek,
   I was able to get "jave" running, and that may do what I need.  Since 
I receive the list in digest form, any attachments get scrubbed.  I'd 
like to be free to do simple drawings in line.
   Thanks again

On 10/06/2011 03:26 AM, emc-users-requ...@lists.sourceforge.net wrote:
> Cogoman:
>
> A quick Google search suggests JavE might suit.
>
> It's just my two-cents worth, but I think you'd be better off just using
> the drawing tool you like best and placing a png or pdf file of the
> result in one of the file-drops used already by list members.
>
> Regards,
> Kent
> From: Przemek Klosowski  Subject: Re: 
> [Emc-users] Simple DC motor controller To: "Enhanced Machine 
> Controller (EMC)"  Message-ID: 
>  
> Content-Type: text/plain; charset="iso-8859-1" On Wed, Oct 5, 2011 at 
> 11:50 PM, cogoman  wrote:
>> >  BTW... does anyone know of a good ASCII drawing program, so I can easily
>> >  make drawing that won't get scrubbed by the list software?
> http://www.tech-chat.de/aacircuit.html  is a Windows program that
> almost works in Wine (I get screen garbage, fixable by reopening the
> window).
>
> Also, asciio, which is packaged with e.g. Fedora, using the attached
> electronic symbols module (you need to add it to the library, and
> modify setup/setup.ini )


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Re: [Emc-users] Simple DC motor controller

[cogoman]

On 10/05/2011 11:36 AM, emc-users-requ...@lists.sourceforge.net wrote:
> The problem with the power-amp ideas is that that I don't see how that
> would drive the motor in the reverse direction, I think an H-bridge is
> needed. (unless we were to hold one terminal of the motor at 6V, and
> drive the other to 0V and 12V, I suppose)
You can probably find a better solution in a motor driver kit, but if 
you were to try the car amplifier method, as long as both *inverting* 
and *non-inverting* inputs are brought out to use, it's doable.   You 
rig up both amplifiers as unity gain inverters, and use the output of 
one amp to drive the inverting input of the other.  You have to figure 
out how to make the +-11V input at 0 volts cause the first amplifier to 
drive +6 volts (or half of the supply voltage) and reference the other 
inverting amplifier to half the supply voltage.

BTW... does anyone know of a good ASCII drawing program, so I can easily 
make drawing that won't get scrubbed by the list software?

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Re: [Emc-users] VFD Speed Input

[cogoman]

On 10/02/2011 01:38 PM, emc-users-requ...@lists.sourceforge.net wrote:
> After having more experience with getting my PWM to VFD input working,
> it comes to my mind that what is behind the VFD input is an ADC, which I
> think takes a snap shot (sample/hold) at a frequency. I seem to recall
> one VFD manual stating the sample frequency at something around 500 Hz,
> and others in the tens of kilohertz. This seems to indicate that the
> input will sample whatever voltage happens to be on the input at a
> given, but regular, instant in time. With raw PWM this is typically
> either 0 or 10 Volts. With filtered PWM, the voltage could be anywhere
> along the charge/discharge ramps. It seems with a push/pull on the
> input, it may actually make things worse by making the input more like
> raw PWM. If my thinking is correct, ideally each PWM cycle would be used
> as a data point to drive a stable voltage output for that particular
> cycle. Even then, it might be better to block a sample that happens
> right on a cycle change or filter only close to that point to smooth the
> change.
If you're looking for an easy way to drive both high and low through a 
resistor into the smoothing capacitor, I recommend a 555 timer circuit.  
Notice at the link below you need no extra components to make the 555 an 
inverting Schmitt trigger.

http://www.kpsec.freeuk.com/555timer.htm#buffer

Using the opto isolator circuit mentioned earlier in this thread if you 
add the output transistor of the opto on the correct side of the 
trigger/threshold node, and a resistor to the opposite side, you can 
make the whole circuit non-inverting.  The beauty of the 555 is if you 
already have the opto, the resistor, and the capacitor of the filter, 
one more resistor and the 555 should be all you'll need to let the PWM 
produce 0-10V, and most 555s are good for up to 18 volts of supply.

   If you need to control a 555 from a TTL output, just put an LED 
between the control pin and ground. that will set the trip point for an 
input logic high at about 1.5 volts (the voltage across the LED) and the 
logic low trip point of 1/2 that (about .75 volts).  Luckily, these are 
within the standard output levels of a TTL chip.  3.3 volt CMOS logic 
will have outputs which work with this arrangement.

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Re: [Emc-users] 3-phase pwmgens for 7i39

[cogoman]

On 09/30/2011 07:52 PM, emc-users-requ...@lists.sourceforge.net wrote:
>> >  Is there any chance that I have to set something that is not 8? That
>> >  Keling's spreadsheet says that motor has 8 poles.
It took me a while to find this web page:

http://www.southernsoaringclub.org.za/a-BM-motors-3.html

The topic covered is using stators from old CDROM motors to wind new 
powerful outrunner motors, which are a type of brushless DC motor.
There are 5 pages in this series, and they give a comprehensive look at 
winding and driving brushless DC motors (at least the RC type.

   Though there may be an exception to the rule, the rule is that all 
BLDC motor controllers for RC vehicles are designed to drive 3 coils, or 
phases.  RC controllers are meant to drive a motor at reasonable speeds 
so that they can get the motor going in an asynchronus manner, and when 
it gets moving fast enough they can check winding voltage to find out 
when to switch the electronic commutation.  The motor will have stators 
with poles in multiples of 3.  For a 9 pole stator, generally each coil 
will be wound around 3 poles equally spaced apart.

   For a servo motor a lower limit even as low as 300 RPM would be too 
much for the application, so BLDC servo motors have hall sensors, or 
incremental encoders to provide feedback for commutation.  If the motor 
comes with 3 hall sensors, then it "should" be intended to be driven 
with a 3 phase driver.  Inside it could have 3, 6, 9, 12, 15, or 18 
poles (or perhaps more), but it will still only have 3 distinct coils, 
and 3 phases of drive.

   If Keling says there are 8 poles, perhaps there are, but that would 
probably require a four phase controller, and that would be unusual.
*
   The final word, if there are only 3 hall effect sensors, you should 
only have to be concerned about 3 phases.*

   Check out the chart on the web page above.  Also recommended, even if 
you are not planning to fly an RC airplane with the guts of your defunct 
CDROM drive, are the other 4 pages of this series.  They may give you 
more insight into what's happening under the case of that expensive 
servo motor that you wouldn't want to take apart.

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Re: [Emc-users] Parallel port messages... What happens?

[cogoman]

   I just looked at it briefly.  Actually not too briefly, but if what I 
need is in there (and it might be) it's going to take a bit longer to 
find and understand it.  The AVR code isn't an issue since I was hoping 
to use one of the much faster ARM micro-controllers out there.
   Thanks.

On 08/13/2011 11:59 AM, Kirk Wallace wrote:
> Have you checked out the AVR and Modbus pages on the wiki?
> http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?AVR
> http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?FPGA
> http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?VFD_Modbus





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Re: [Emc-users] Parallel port messages... What happens?

[cogoman]

On 08/12/2011 02:10 PM, andy pugh wrote:
> This is a simplification. Address auto-indexing and translation ram
> (where contguous memory addresses link to non-contiguous registers)
> confuse the matter.
>
> Why are you asking?

This is a simplification. Address auto-indexing and translation ram
(where contguous memory addresses link to non-contiguous registers)
confuse the matter.

Why are you asking?


   I have a seminal idea I'm trying to reason out (or away.)  A while 
ago there was a thread here about interfacing to an ARM micro-controller 
on the parallel port.  I expected EMC2 to read position data for 4 or 5 
axes from the P-port, read homing and limit switch states, do some 
calculations with the data, and then send velocity information for 5 
axes back to the P-port.  I'm thinking about a stepper system that would 
use existing P-port messages and act like a servo system to EMC2, but 
cost a lot less than a real servo system.  I was hoping EMC2 would ask 
for information, and get back a series of bytes that covers all it needs 
to know, then do multiple writes in a clump; so the micro-controller 
wouldn't have to drop everything for long.  Address-data address-data 
address-data seems like a lot of overhead.
   I'd just hate to have to write a new interface for a 
micro-controller.  More work.  Of course I'll probably never get to 
implementing any of this, but I like to dream.  I'm definitely an idea 
hamster.

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[Emc-users] Parallel port messages... What happens?

[cogoman]

What is the sequence of messages sent and received to an FPGA parallel 
port servo card at each servo interval?  I looked on the wiki and 
couldn't find this information.  What all goes on when controlling 3 
servos over the parallel port?

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Re: [Emc-users] Questions about your Stepper kit

[cogoman]

On 08/11/2011 08:28 AM, Mark Wendt wrote:
>   I knew about the properties of the torque fall-off of steppers, and
> that servos generally kept their torque at higher rpms, obviously much
> better than steppers.  i was just wondering why motors were listed with
> power ratings rather than torque, since torque is more along the lines
> with how we determine what we need from a driven motor than power.  Must
> be like you said, HP, especially in motor vehicles seems to be a selling
> point, kinda like "billet" aftermarket auto parts.  To me, anyway, I
> would much rather have the torque ratings up front, and in an industrial
> environment, where somebody is going to use that product to drive a
> machining operation, I would think the integrator would much rather look
> at what really needs to be looked at, not the eyewash.
I believe it's all necessary.  The power level is to let you know how 
hard you can drive the motor without letting out the magic smoke.  It 
doesn't translate well into torque or RPM mathematically because 
efficiency of the motor can make that swing wildly, and a 90 percent 
efficient motor designed for speed will have much lower torque at rated 
power than a 90 percent efficient motor designed for torque.  You can't 
equate current with torque either, since two of the same motor core and 
magnets; one wound 10 turns of thick wire, and the other wound with 20 
turns of a thinner wire will produce different torques at the same current.

   The power rating is probably there to let you know that if you push 
it beyond that for any length of time, and let out the magic smoke, they 
won't just replace the motor for you every week.

   With a servo motor you usually have a max current rating, and a max 
voltage rating.  The supply is usually chosen so that max power supply 
voltage times max motor current will be many times the motor max power 
because the spinning rotor develops back EMF (Electro Motive Force, or 
voltage).  You need the higher voltage to push current in when the back 
EMF gets high due to high speed operation, such as going to and from the 
tool holder.  That same voltage is enough to supply too much current 
when you are trying to push a 2" shell mill through stainless steel, or 
cut away a large chunk of aluminum.

   Our Shizuoka has about 90V available for the servo motors, and 
probably needs all of that to push a few amps at 3000RPM (due to back 
EMF canceling out much of the voltage), but in a stall, it needs much 
less voltage to push up against the 10 AMP current limit.

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[Emc-users] live cd staleness

[cogoman]

   I feel your pain somewhat, but I've worked through many of the difficulties. 
 When you run the live CD (I used the latest Ubuntu 10.04), the first time you 
try to run the sim AXIS, it asks if you'd like to copy the files to your home 
directory.  I answered YES.  It makes a copy of all the EMC2 stuff in your home 
directory, which is:

/home/ubuntu

When you try to run a program, there are two red buttons on the left.  The 
leftmost is the ESTOP, and you must click it to get it out (out of ESTOP).  The 
next one is the power button, and it needs to be clicked to push it in, but it 
doesn't look much different when it's in than when it's out.  Then you try to 
run the program that is loaded by default, and you get the error you cited.  I 
don't know the exact phrase, but your paraphrase is accurate.  At this point 
click on "MACHINE" then a pull down menu gives you access to "Homing" then you 
can click on Home All.  EMC2 will do some fancy stuff, and then let you run a 
program.

   The programs in

/home/ubuntu/emc2/nc_files/examples  (perhaps there's another level I've missed)

   are owned by root, who you aren't since you are ubuntu.  The solution is to 
open a terminal window and type

cd /home/ubuntu

then type :

ls -l

to see if anything is owned by root.  If it is, then type

sudo chown ubuntu:ubuntu *

   Forgive me if you are more advanced than my instructions convey, but 
sometimes the extra stuff may help.  The 'sudo' allows you to act as root.  The 
'chown' says to change the owner of files or directories.  the first ubuntu is 
the new owner, the second ubuntu is the new group.  Don't know if the second 
one is needed, but so far it hasn't hurt me.  The star says to change every 
file or folder you find.  If this isn't the case, perhaps someone else will 
correct me.

   Now we need to go to the next directory:

cd emc2
ls -l

   If there's anything that needs ownership change, change it.  If not, let's 
go on.  The next directory should show in the listing in case I get the order 
wrong, or leave a level out since I'm not booted up into EMC2 ubuntu (you see 
I'm running Linux Mint for EMAIL purposes and all non EMC2 stuff because ubuntu 
thinks I don't deserve write access to my other hard drives.)

   I believe from EMC2 there are two options, the one in which the 
configuration files are kept, and nc_files.  If your mileage is like mine, you 
may have to edit axis.ini, and (at least in the simulator) make EMC2 believe it 
has and enormous Z-axis to handle programs.  The axis positive and negative 
limits are near the end of the file, and I usually have trouble with going 
beyond the Z axis limit.  Again if this is owned by root, you will need to 
change owners.

   If you don't have security issues, so you don't need this PC protected by 
passwords, and you have already installed EMC2 ubuntu, then you may be able to 
get rid of your password by opening a terminal.  Click through:

Applications-->Accessories-->Terminal

Then to become root type:

sudo su

Then to delete your password type:

passwd --delete ubuntu

or... instead of 'ubuntu', whoever you chose to be during the installation.

   If you want a password, but want to be logged in automatically when ubuntu 
starts, then delete your password (as shown above) then close the terminal.  
Then click on:

System-->Administration-->  Users and Groups

   On the left click on the user you are just to highlight it.  Then on the 
right, password should say 'none'.  Click on 'Change' to the right of none.  
Then you can enter a new password, and check the box that says 'Don't ask for 
password on logon'.

   Grace to you in this matter,
   cogoman

On 08/08/2011 08:14 AM, charles green wrote:


ubu8 and ubu10 + emc2 installs both provide the Axis gui errors, "cant do 
anything without homing" for any mdi command following the machine completing 
the homing sequence.? is there a way to get an up to date live cd with relevant 
patches and current bug fixes, or is the distribution only intended to be a 
'let's see what happens' type of thing for fluent command line linux personnel?



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Re: [Emc-users] Old ssh -Y problem is back

[cogoman]

On 08/02/2011 03:06 AM, Erik Christiansen wrote:
> Together, I'm sure we can make it do what you want. IIUC, that is to
> start the xterm in a directory other than $HOME. (i.e. '.' is
> /some/other/directory)

Thanks,
  You gave a lot of options to try.  I suspect oat least one will work well! 
I'll try them when I get to the PC I use puppy on.


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Re: [Emc-users] Old ssh -Y problem is back

[cogoman]

On 08/01/2011 08:10 AM,

gene heskett wrote:

> I have one mailing list in kmail that goes back a decade or more, several
> gigabytes that I like to take everything up to a year ago and move to a
> different folder for storage, but I haven't even started on a script to do
> that.  It takes kmail about 10 seconds to find a new message, and half an
> hour to rebuild the index.
   I currently get this list in digest form, and I like to keep old 
messages around to search for stuff I know has been covered like Yann's 
glue machine.  Thunderbird was slowing to a crawl, and someone on here 
mentioned to someone else that the mailbox may be getting too big.  Now 
I have a mailbox for volumes 30-39, volumes 40-49, etc under my main CNC 
mailbox.  I set up message filters like so:

if Subject contains "Vol 7" move message to "Volume 70-79" on cogoman.

   I set up filters that would trash any EMAIL that came from the server 
that sent me Viagra messages.  I figured no one with a real reason for 
EMAILing me would be on one of those servers.  Unless Optimum.net has 
better filtering than I do, it has worked quite well.


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Re: [Emc-users] Old ssh -Y problem is back

[cogoman]

From: Erik Christiansen

> But if the additional script is used, it can also open mutt in an xterm
> in the top right corner,
   Maybe you can solve a problem that I have been having.  I have been 
trying to get an icon on the desktop in Puppy Lucid 5.25 to open up an 
xterminal with the default directory as something different from the 
default.  I even tried a shell script that would just change 
directories, but as soon as I exited the script, it kicked me back to 
the default directory.  Puppy runs from RAM, so I am sure the xterm used 
is a small simple one.  Anyone have a suggestion?

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[Emc-users] Questions about your Stepper kit

[cogoman]

It's not so much the 2.1 ohms, though that can be an indication of high 
inductance.  It's the 9mH per phase that slows you down.  If you take a 
quick look at the graphs in the following WIKI page:

http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Stepper_Motor_Speed_Limitations

   they will give you a feel for what voltage/inductance/current 
combinations will limit full step torque to.  I know it's not a direct 
speed equation, but it's helpful. looks like a 90V supply would take a 
little over 300uS to get that 9mH coil to 3A.  45V would take over 600uS 
and 30V around 900uS.  1 mS per step (rounded) is only 1000 steps per 
second (2.5 RPS or 150 RPM), and that's not even at full torque.

   For a fairly quick system I would look for less than 3mH per coil, 
preferring 2mH.
> The stepper resistance looks a bit high at 2.1ohm/phase. You wont get much
> speed on the supplied 24V psu.


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Re: [Emc-users] bad news, xylotex died

[cogoman]

I read in Machine Design, or some other tech mag in one of those device 
forensics columns about a company that was getting their servo drives back from 
just one company at a rate of 4 failures a month.  The engineer sent to check 
on it did some checking before he left and found that there was metal 
particulate matter on the circuit board that shorted it out.  When he got to 
the factory, the machine it was on produced a lot of metal dust and shavings, 
and their control box had fans, but no filters on it.

   At work we have FADAL machining centers, and they have a fan and filter on 
the outside which blows cool air over a heat sink mounted in the side of the 
cabinet.  on the other side of the heat sink was a fan to circulate the cool 
clean air from the heat sink to the drives inside the cabinet.  With coolant 
flowing there is still enough airborn debris to clog a 4" by 4" filter in a few 
weeks.  I suggest buying an A/C filter from the big box store, and building a 
mount for at least a 12" by 12" piece of filter on the input side of your 
air-stream.

On Saturday, July 30, 2011 11:20:01 PM R. van Twisk did opine:

> As was my 4 axis xylotex, in a box that exactly fit a pair of ball bearing
> psu fans, one in each end, one sucking in and one blowing out the other
> end.  With 19 volts on those fans, they fairly screamed, so the xylotex was
> probably getting 4 or 5x its recommended airflow.  And the fans were still
> screaming when I heard the pops of the A-3977's blowing their heat sinks
> off in response to my tapping the ->  arrow key on the keyboard.


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Re: [Emc-users] OT -- Ethernet thermometer?

[cogoman]

   You guys amaze me! There must be at least 7 different solutions to 
the problem here, and ultimately, you solved his problem with a solution 
that may cost him nothing!  And that tip about orienting the dial is 
very valuable too!

   I have been thinking about all the toys and routers and stuff that 
use microcontrollers, and figured that AVRFreaks or some other site 
should start a thread on cheap cast off electronics that provides useful 
microcontrollers/motors/LCD displays for hacking.  I am wondering about 
"Scrabble Flash", as it looks like $25 buys 5 microcontrollers, and 5 
dot matrix LCD displays for hacking.  They could be mask programmed, 
which would make them useless, but if they are flash, and even better 
AVRs, they would make a great inexpensive uC development board.  And if 
you burned it out, you have 4 spares.  Since they keep a dictionary, 
they probably have a lot of memory too.

   I'm going to wait for one of you to post a link to that page, since I 
can't be the first who has thought of that.

   kudos to the EMC2 support network!
> If you don't need high accuracy - the temp sensors that are used by 
> indoor/outdoor clocks can be
> used with receivers that can switch between several transmitters. - look for 
> weather station stuff
> on Google..
> 
> Do you want to log the data or just read it remotely?
>
> You can get a cheap IP Camera for about $35 and aim it at a thermometer.
> http://www.amazon.com/AirLink101-SkyIPCam-Network-Webserver-Ethernet/dp/B004VBA5MM/ref=sr_1_2?s=electronics&ie=UTF8&qid=1311371975&sr=1-2
>
> Or one of these equipped with a K thermocouple probe?
> http://www.harborfreight.com/ac-dc-digital-multimeter-37772.html?utm_campaign=SEO&utm_medium=Inbound_links&utm_source=linking
>
> This is pretty cheap for it being a finished product.
> http://www.controlbyweb.com/temperature/index.html?gclid=CJynsbbylaoCFQFubAod0hAe3Q
>
> I'd go with the webcam inside the coop and include a big dial
> thermometer it in the view of your chickens..
> You might be able to check on their feed level and water level and temp
> if you arrange the camera carefully.
>
> Look at the bright side... perhaps you can get a big new "John Deere"
> dial thermometer from the feed store.:-)
>
> One suggestion based on automotive racing, orient the thermometer so
> that the preferred temp range is straight up. That way a quick glance
> will tell you whether it is warm enough or not.


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Re: [Emc-users] How can I create my own functions table for named subroutines

[cogoman]

In the past I have thought that it would be great to have a feature in 
EMC2 like the C pre-processor, that would do some automatic replacements 
to allow the original G-code to be more readable.  It seems like two 
threads here can collide, and the solution for the thread on 
substituting A for E could give us a solution to the named subroutines 
problem.

the previous solution used filters in the ini file:

This is my filter section in .ini
[FILTER]
PROGRAM_EXTENSION = .png,.gif,.jpg Greyscale Depth Image
PROGRAM_EXTENSION = .py Python Script
PROGRAM_EXTENSION = .gcode Extruder gcode
png = image-to-gcode
gif = image-to-gcode
jpg = image-to-gcode
py = python
gcode = E2A

This is E2A that was run from outside of AXIS before
#!/bin/bash
sed -e 's/\( E\)\([0-9]*\)/ A\2/' $1
Guru comments on this?

Here we just have to adjust our sed line to get editing scripts from a 
file like so

sed -f subroutines.sed $1

now we can have scripts to replace text subroutine names with the 
numbers EMC2 seems to like so much, IE:

 s/rectangular-pocket/500/
 s/peck-drill/501/
 s/leave-a-tab/502/

Now you can use whatever names look good to you, and before EMC2 sees 
the code, it will be changed to a simple number.  It will only replace 
the first instance of the phrase on each line, so if you put the 
subroutine name in a comment at the end of the line, it will survive 
sed, but will let you keep track of subroutines in AXIS.

Comments anybody?

On 06/24/2011 06:11 PM, emc-users-requ...@lists.sourceforge.net wrote:
> So is it possible to create such a table? I tried to initialise 
>  table
> using code above but got an error message Parameter number out of 
>  Range
> I suspect the answer is no you can't - see later caveat.
>
> You can of course do this sort of thing, because it is based upon
> numbers and that is all a parameter can hold
>
> /o<200>   sub/
>
> / (msg, In 200-sub)/
>
> /o<200>   endsub/
>
> /o<201>   sub/
>
> / (msg, In 201-sub)/
>
> /o<201>   endsub/
>
> /#<_index>   = 0/
>
> /o   sub/
>
> / o100 while [#<_index>   LT 2]/
>
> / o[200 + #<_index>   ] call/
>
> / #<_index>   = [#<_index>   + 1]/
>
> / o100 endwhile/
>
> /o   endsub/
>
> /o   call/
>
> /M2/
>
>> This is E2A that was run from outside of AXIS before
>> >  > #!/bin/bash
>> >  > sed -e 's/\( E\)\([0-9]*\)/ A\2/' $1
>> >  >  Guru comments on this?
> >  


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[Emc-users] Axis naming X Y Z E, can I have that?

[cogoman]

This is only a band-aid approach, but it gives me a chance to plug the 
"Stream Editor".  The stream editor "sed" when used with an edit file is 
kind of like a super-colossal macro generator.  It is VERY cryptic when 
you first get started, but with just a little knowledge of how to use 
it, it can make jobs like this a non problem.  If there is no other use 
of "A" in the file...

sed s/A/E/ gcodeoutput.ngc > gcodeoutputE.ngc

   I have been so impressed with the power of sed, that I hope to 
inspire some programming types to write a GUI front end for it that 
would phrase the substitutions in plain English ways, and then show the 
sed command to accomplish that, and eventually run all of the editing 
rules against the file.  This would make the Stream Editor available to 
the novice, but teach the command line stuff to them for future use.

   Here is a link to a site with sed info.  I've found that u-sedit3 is 
a good tutorial, and the download is listed on this page.

http://www.cornerstonemag.com/sed/
> Hi Group,
>
>
>
> I would like to have three linear axes X Y Z and a rotary axis named E
> instead of A.
>
>
>
> G-code generated for me uses E for plastic extrusion feed. Up to now I edit
> axis E to axis A (almost automatically) before running, but I would like not
> to do this extra step.
>
>
>
> As I understand it axis order is XYZABCUVW and nothing else?
>
>
>
> Another thought if the G-code could be generated wit A instead of E. I am
> looking into that too.
>
>
>
> Or maybe it can be handled entirely differently?
>


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Re: [Emc-users] Suicide brakes on an AC universal motor?

[cogoman]

On 06/01/2011 07:36 PM, emc-users-requ...@lists.sourceforge.net wrote:
> The resistor I did use when I was building the interface for my mills
> spindle, because I read someplace that a dead short could result in field
> demagnetization under the right conditions.  There I used a 20 ohm 20 watt
> resistor, which seems to be major overkill as I can just barely detect that
> heat after about 20 starts&  stops in as many seconds.  There, the stop
> down to about 30 rpm is maybe 1/2 second, and another half second has it
> stopped.  Grabbing the spindle and turning it by hand is like stirring cold
> karo syrup.
*It seemed counter-intuitive to me, but from reading stepper motor 
controller data sheets I've found that if you short out a winding, the 
current takes longer to decay than if you put a resistor across it, and 
make it pump energy into a higher voltage. I don't know how this applies 
to the changing fields in a spinning universal motor, though.*


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Re: [Emc-users] OT made a new milling enclosure

[cogoman]

On 04/08/2011 10:30 AM, emc-users-requ...@lists.sourceforge.net wrote:
> Message: 3
> Date: Fri, 8 Apr 2011 06:54:27 -0500
> From: Igor Chudov
> Subject: Re: [Emc-users] OT made a new milling enclosure
> To: "Enhanced Machine Controller (EMC)"
>   
> Message-ID:
> Content-Type: text/plain; charset=ISO-8859-1
>
> It is good stuff, but as for bending it cold, one needs a big brake. I do
> not personally have that. So, to bend it I heat it up.
My Father told me that he used to clamp a piece (of Lexan) up in a vise, 
and take a sledge hammer to it.  It eventually assumed the shape he was 
aiming for  8-).


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Re: [Emc-users] Guidance on usb comp

[cogoman]

On 02/24/2011 01:35 PM, emc-users-requ...@lists.sourceforge.net wrote:
> It would be nice if there was a way to interface CNC equipment via USB such
> that the timing of actions was being scheduled in the controller rather than
> by the host O/S.
>
> That way it would not be necessary to run a specific version of the O/S
> hacked up to provide real time scheduling. All that would be necessary would
> be to have the host able to guarantee response within a few seconds.
>
>
> Parallel ports are effectively obsolete these days and finding a motherboard
> with support is starting to confine selection. So this is effectively
> meaning I have to use an obsolete machine that I am not sure I could replace
> in a hurry.
Sounds like the NGX BlueBoard-LPC1768-H might be all the hardware you'd 
need.

http://shop.ngxtechnologies.com/product_info.php?cPath=21&products_id=65 



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