Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors

[andy pugh]

On Sat, 22 Aug 2020 at 02:22, Chris Albertson  wrote:

> One other easy trick is to have two CAN busses one for left and the other
> for right.

One bus per leg makes sense to me. The intra-leg coupling needs to be
a bit tighter than the inter-leg

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors

[Chris Albertson]

I don't think it actually runs that fast, I think you calculated the
maximum rate possible with one motor on the bus.

More reasonable is to assume 20 updates per second and 12 motors on the
bus.  This rate could work.   I looked for 10 minutes through the Chetha
code in Gethub and foud they do update all the motors every "dt" but I
could not find where dt is set. But itis likely about 0.05 second.


One other easy trick is to have two CAN busses one for left and the other
for right.   You would never need to send data from one leg to the other so
this could work.

On Fri, Aug 21, 2020 at 4:45 PM Frank Tkalcevic 
wrote:

> I was looking in more detail at the MIT Cheetah and found this page -
>
> https://www.robotdigg.com/product/1667/MIT-Robot-Dog-high-torque-Joint-Motor
> -or-DD-Motor
> 
>
> It says that each motor takes an 8 byte payload to drive a motor, and that
> motor then replies with a 6 byte packet.  After you add the CAN headers and
> trailers that is a total of 200 bits, best case, or about 416 updates per
> second for 12 motors on 1MHz bus.
>
> I was expecting the update rate to be a lot lower than that (I should have
> done the math).
>
>
> -Original Message-
> From: N [mailto:nicklas.karlsso...@gmail.com]
> Sent: Saturday, 22 August 2020 5:34 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors
>
> > ...
> > On CAN you can take advantage of the fact that all devices read the bus
> at
> > the same time.  Each reader decides what information it wants to read and
> > ignore the rest so a time-sync heartbeat could be implemented if the
> nodes
> > all needed to be time synchonized. ...
>
> Yes all devices need to read bus within the time it take to send one bit
> because of the arbitration used to send the message with highest priority
> first. With CAN-FD speed is increased after address is sent so that message
> could be larger.
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors

[andy pugh]

On Sat, 22 Aug 2020 at 00:45, Frank Tkalcevic
 wrote:

> trailers that is a total of 200 bits, best case, or about 416 updates per
> second for 12 motors on 1MHz bus.
>
> I was expecting the update rate to be a lot lower than that

And you are assuming one bus.

On the cars I work on we have a private CAN between the engine and
gearbox, and then two high-speed CAN networks that both are on too.

Potentially they could run one bus per motor, but one bus per leg
would make sense.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors

[Frank Tkalcevic]

I was looking in more detail at the MIT Cheetah and found this page -
https://www.robotdigg.com/product/1667/MIT-Robot-Dog-high-torque-Joint-Motor
-or-DD-Motor

It says that each motor takes an 8 byte payload to drive a motor, and that
motor then replies with a 6 byte packet.  After you add the CAN headers and
trailers that is a total of 200 bits, best case, or about 416 updates per
second for 12 motors on 1MHz bus.

I was expecting the update rate to be a lot lower than that (I should have
done the math).


-Original Message-
From: N [mailto:nicklas.karlsso...@gmail.com] 
Sent: Saturday, 22 August 2020 5:34 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors

> ...
> On CAN you can take advantage of the fact that all devices read the bus at
> the same time.  Each reader decides what information it wants to read and
> ignore the rest so a time-sync heartbeat could be implemented if the nodes
> all needed to be time synchonized. ...

Yes all devices need to read bus within the time it take to send one bit
because of the arbitration used to send the message with highest priority
first. With CAN-FD speed is increased after address is sent so that message
could be larger.


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users



___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

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

[Gene Heskett]

On Friday 21 August 2020 15:35:26 Gene Heskett wrote:

> On Friday 21 August 2020 12:45:11 Chris Albertson wrote:

> Checking just now, its up to a 
> step over a mm up, the brim looks pretty gossamer, but the higher
> stuff doesn't look like its starving, just on a diet. Might have a
> usable part. Later, its looking like a good part about 1/2 done.
>
> It only took a 5 minute run to break the flexgear I'd made out of
> white PLA with the old hotend, and the next one I made about .1%
> smaller, had enough elephants foot I'll never make it work.

I got that one fixed, took it to the lathe. Sharpened up a cutoff blade 
and gave it a cheap shave.

Now I'm building the bigger piece of the wave gear bearing carrier, and 
feel I finally have enough plastic. st/mm is now 250, and flow is at 
150% and its not looking too shabby. I should flag the fiber, and check 
the delivery for a 100mm push at some point, but don't know how without 
removing the nozzle, and convincing Merlin to move it cold, which it 
will not do.  There's now about 1.5" between the fiber drive and the 
nozzle. 3.5 cm maybe.

The mail has come,

> And the tpu still hasn't appeared. Shoulda been here on the 17th.
> Story of life in rural WV, hurry up so you can wait longer. :(
>
> Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] 7i73 Lagging jog key

[Thaddeus Waldner]


I appreciate all the help. This is a low-priority project and I don’t have much 
time to work on it and I‘m learning as I go here.

I’ve tested all main powered devices for ground loops by individually 
disconnecting each ground and testing with an ohm meter. It appears that I took 
Gene’s advice early on when building this setup and grounded devices only at a 
single point. One exception is that my “single point” is actually a strip of 
grounded Wago terminals. At any rate, my scope doesn’t pick up much noise 
anywhere on the power supply or return lines.

In the process of testing the grounds, I discovered that I had the return to  
both DC power supplies (5v and 24v) joined but not grounded. Now these are 
grounded. This appears to have taken care of part of my issue. Now each 
keypress registers as a rise and fall in HalScope, regardless how quickly I jab 
the key.

For what it’s worth, the noise profile on the keypad signals does not appear to 
have changed at all. I measured it by arming the scope trigger and sweeping the 
trigger voltage up... it triggers at about 2.7v, which is 0.6v from the 3.3v it 
should have, or about 1.2v peak-to-peak noise. I don’t know what the 
significance of this is. As far as I can tell, it has to be EMI picked up by 
the membrane keypad. I’m doing all measurements with an undgrounded scope and 
test probe grounded to to the board ground. Is this noise a cause for concern?

Finally, the machine appears to use a different acceleration when jogging from 
the keypad, than when commanded from gmoccapy on-screen jog buttons. 
Double-clicking the gmocapy jog buttons results in two successive moves. 
Double-tapping the keypad button shows up as two pulses on the keycode pin in 
the Halscope, but results in one continuous axis motion. As I mentioned at the 
top, I have the keys mapped to halui.axis pins. Where do I look?

> On Aug 19, 2020, at 1:43 PM, Peter C. Wallace  wrote:
> 
>  keycodes


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] setting tool length offsets

[andy pugh]

On Fri, 21 Aug 2020 at 21:11, jrmitchellj  wrote:

> OK, I see it correct under the GUI section, but i was looking under the
> next section  (G-Code Programming) that shows it with the older method.

Can you be more specific? A link would help.

Or, better still, fix it and make a pull request on Github.

> Another question on this subject, In the touch-off window, is P0
> just shorthand to touch off in the current workspace (G54, G55, etc)?

Yes. Both buttons actually just issue different types of G10 command.


-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] setting tool length offsets

[jrmitchellj]

OK, I see it correct under the GUI section, but i was looking under the
next section  (G-Code Programming) that shows it with the older method.

Another question on this subject, In the touch-off window, is P0
just shorthand to touch off in the current workspace (G54, G55, etc)?

--J. Ray Mitchell Jr.
jrmitche...@gmail.com


"Good enough is the enemy of excellence"author unknown


On Fri, Aug 21, 2020 at 11:34 AM andy pugh  wrote:

> On Tue, 18 Aug 2020 at 16:11, jrmitchellj  wrote:
> >
> > I just checked the 2.7 & 2.8 versions documentation, and they have the
> same
> > description as teh 2.9 version.
>
> And that should now be the same, but different.
> http://linuxcnc.org/docs/devel/html/gui/axis.html
>
>
> --
> atp
> "A motorcycle is a bicycle with a pandemonium attachment and is
> designed for the especial use of mechanical geniuses, daredevils and
> lunatics."
> — George Fitch, Atlanta Constitution Newspaper, 1912
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>

___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

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

[Gene Heskett]

On Friday 21 August 2020 12:45:11 Chris Albertson wrote:

> You remind my of something I always do and it would help with you
> adhesion problem and allows parts to be removed with less effort.   I
> always place a fillet around the edge of the part. So whatever
> surface is touching the build plate should have a fillet, even if it
> is only 0.5mm radius it helps to allow a putty knife to get under the
> part. You have to add this using the CAD software.   Yes, Cura can
> shrink the size of the first layer but it is not the same as a fillet
> and you may have to do both to get a nice round edge.

I sharpen my putty knife on a 12,000 grit rouge wheel, wet if I'm not too 
lazy to carry it a gallon of water for the water dribbler. It gets under 
a gnat w/o shaving a hole in his shoe soles. ;)
>
But last night, after installing the micro-swiss hot end and extruder 
drive combo, their recommendation of an extruder drive of about 130 
step/mm left it without near enough extrusion, and I was pumping it up 
5% at a time with tune menu's flow setting, and that almost made it 
work, but I was still getting dashes with a tail, not a steady line 
laydown. The motion of the extruder drive seem quite excessive as it was 
makeing a small part, but I needed to check my eyelids for leaks, so I 
turned down the flow feed about 25% and took a nap.  When I came to, 2 
hours later the part was following the head around and both were buried 
in a golf ball sized gob of steel wool, only plastic. The bottom of the 
hot block was encased in plastic, and the sock was expanded.  All 
evidence pointed to plastic comeing down thru the nozzles threads!

I gave up and went back to bed,  This morning I rustle up a 7mm socket, 
heat the extruder up to about 240 and removed the nozzle. Wrapped a 
couple layers of plumbers teflon tape around the threads, started it 
about half a turn and warmed the hot block back up to 240 and tightened 
it 1/8 turn from stripped.  Noted the fan was stamped as a 24 volt.  So 
now I know which fans to buy. Restored their recommended settings for 
steps/mm, re-leveled the plate and I've been doing 1 or 2 layers at a 
time, looking for the right feed and heat to make it stick, and looking 
at spider webs blowning in the wind until just now, its laid down a brim 
that was stuck when I got up to do something about my coffee cup whose 
bottom was turning into the Sahara, and to check for incoming mail. 
Checking just now, its up to a step over a mm up, the brim looks pretty 
gossamer, but the higher stuff doesn't look like its starving, just on a 
diet. Might have a usable part. Later, its looking like a good part 
about 1/2 done.

It only took a 5 minute run to break the flexgear I'd made out of white 
PLA with the old hotend, and the next one I made about .1% smaller, had 
enough elephants foot I'll never make it work.

And the tpu still hasn't appeared. Shoulda been here on the 17th.
Story of life in rural WV, hurry up so you can wait longer. :(

Thanks Chris.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors

[N]

> ...
> On CAN you can take advantage of the fact that all devices read the bus at
> the same time.  Each reader decides what information it wants to read and
> ignore the rest so a time-sync heartbeat could be implemented if the nodes
> all needed to be time synchonized. ...

Yes all devices need to read bus within the time it take to send one bit 
because of the arbitration used to send the message with highest priority 
first. With CAN-FD speed is increased after address is sent so that message 
could be larger.


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors

[N]

> I think the question was intended to be more theoretical and asks about
> "exactly" synchronizing commands. The LinuxCNC/SPI solution is not
> that.  SPI works only because it is so fast that the error in
> synchronization is tiny and goes unnoticed.

Using a Micro controller it is possible to connect pwm output to CS signal and 
use it to trigger interrupt to send a message, receive may clock input so if 
needed it is possible to get really good synchronization with SPI and standard 
Micro controller if needed. In doubt there is any case this accuracy is needed 
or make a difference in practice but syncronize clock drift may be needed, 
especially if a FIFO is used.

> Here is a harder problem. Let's say I am in North America and by buddy
> lives in Europe and we want to each run clocks and we want them to stay in
> phase at a high level of accuracy.   To make matters worse assume this is
> the mid-1800s and the radio is not yet invented.  They actually solved this
> problem.  The solution was "mutually observed events" and we use this same
> solution today to keep widely dispersed machines in sync.   In the old
> days, they would observe one of Jupiter's moons from both America and
> Europe and assume they both say the moon transit the planet at the same
> time.  Orchestras use a conductor waving a stick who is "mutually
> observed" by all musicians.Same with a CAN bus, you could, if needed
> use a high priority "clock tick" message that all nodes see at the same
> time.

Know about it and it could be sursingly tricky to agree about event ordering.

> But in real-life.   We accept "close enough" and just us a SPI signal that
> is fast enough that no one notices the error.

Agree, used this approach many times and quite often there is plenty of other 
random variations.


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] setting tool length offsets

[andy pugh]

On Tue, 18 Aug 2020 at 16:11, jrmitchellj  wrote:
>
> I just checked the 2.7 & 2.8 versions documentation, and they have the same
> description as teh 2.9 version.

And that should now be the same, but different.
http://linuxcnc.org/docs/devel/html/gui/axis.html


-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

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

[Chris Albertson]

You remind my of something I always do and it would help with you
adhesion problem and allows parts to be removed with less effort.   I
always place a fillet around the edge of the part. So whatever
surface is touching the build plate should have a fillet, even if it is
only 0.5mm radius it helps to allow a putty knife to get under the part.
  You have to add this using the CAD software.   Ues, Cura can shrink the
size of the first layer but it is not the same as a fillet and you may have
to do both to get a nice round edge.

On Thu, Aug 20, 2020 at 10:23 PM Gene Heskett  wrote:

> On Thursday 20 August 2020 20:37:45 Gregg Eshelman via Emc-users wrote:
>
> > Blue painter's tape on the glass, edges butted together. Wipe down
> > gently with rubbing alcohol to remove the wax that makes it possible
> > to unroll the tape.
>
> I'll have to locate a fresh supply of that stuff, whatever I may have
> squirreled away is years old.
>
> The micro-swiss hot end came in today and got installed, and following
> their directions I'm back to makeing plastic starved prints.  Still
> calibrating it IOW.  It also puts the home 0,0 point clear off the glass
> and I'm still trying to figure out how to move that.  The prime the
> extruder run down the left edge is missing the glass about 2mm's.
>
> Another problem has stuck its hand up and waved at me.  Using the white
> stuff, I'm getting elephants foot on the bottoms.  I think there a comp
> for that in cura, but I've not re-found it yet.
>
> Thanks Greg.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Mist Coolant

[Jon Elson]

On 08/20/2020 09:59 PM, John Dammeyer wrote:



-Original Message-
From: Jon Elson [mailto:el...@pico-systems.com]
Sent: August-20-20 7:36 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Mist Coolant

On Thu, 20 Aug 2020 at 21:36, John Dammeyer
 wrote:

The mill I have has flood coolant but I've never used it.  Read about bacterial 
growth and smell.  No way to easily add an expensive

disk oil separator.  Possibly a belt oil separator into the fill hole might 
work.

Thing is the machine shop may go unused for months at a time.

I used Tri-Cool for a while, and had issues with growth and
smell. Then, I got a bottle of Encool 9 by Engineered
Lubricants, a local outfit.  I could leave the sump for
months and have no problem with growth or smell.  Really
good stuff.  So, there are good coolants out there.  This
was a flood coolant system.

Jon


http://216.119.94.70/Products/Metalworking/MetalworkingProductLine.aspx

A search turned this up.  Doesn't look like they sell retail.  I doubt to 
Canada.

Yes, that's the outfit!  I am just a happy user.  Someday, I 
will use up the bottle they GAVE me as a sample, and will 
try to buy more.  I hope they don't only sell it in 55 
gallon drums.


Jon


___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] Question about 7i80HD and 7i90HD mesa cards

[Leonardo Marsaglia]

I just saw the title. Ones is Ethernet and the other Parallel and spi.
Stupid me.

Leonardo Marsaglia

El vie., 21 ago. 2020 09:38, Leonardo Marsaglia 
escribió:

> Hello to all,
>
> I'm about to purchase a set of cards for the two projects I'm working on.
>
> Basically I plan to use the following setup:
>
>
> ___ 7i33
>   /
> 7i80HD/7I90HD - 7i44 -- 7i70/7i71
>  \___ 7i52s
>
> My main doubt is what's the main difference between 7i80HD and 7i90HD?
> Because the difference in price is not minor.
>
> By the way, I've never used any of the ethernet cards but I assume
> LinuxCNC/hostmot2 is ready to work any of these models?
>
> Thanks as always!
>
> Leonardo
>

___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

[Emc-users] Question about 7i80HD and 7i90HD mesa cards

[Leonardo Marsaglia]

Hello to all,

I'm about to purchase a set of cards for the two projects I'm working on.

Basically I plan to use the following setup:


___ 7i33
  /
7i80HD/7I90HD - 7i44 -- 7i70/7i71
 \___ 7i52s

My main doubt is what's the main difference between 7i80HD and 7i90HD?
Because the difference in price is not minor.

By the way, I've never used any of the ethernet cards but I assume
LinuxCNC/hostmot2 is ready to work any of these models?

Thanks as always!

Leonardo

___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users