Re: [Emc-users] 3 d metal printer

[andy pugh]

On 20 May 2017 at 07:41, a k  wrote:

> hi
> i found this
> https://www.youtube.com/watch?v=wOarxQRKW9o
> that is exactly that i try to build 4 years ago
>

More of the same, plus some CGI to make it look like it actually works..

https://www.youtube.com/watch?v=n2szk5MItRA

It seems like it probably _will_ work in time.

Active magnetic weld-pool control? (Actually, that won't work due to the
Curie point)

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Re: [Emc-users] EMC traffic

[andy pugh]

On 20 June 2017 at 08:50, Erik Christiansen  wrote:

> Incidentally, I've found that the Postscript printer language is sorta
> almost like gcode on steroids. Fighting with a GUI drawing package
> gives me chest pains, without producing useful output,
>

Have you seen OpenSCAD? 3D CAD at the command line.

An example usage: https://youtu.be/IPtF5c8o-10?t=4m30s

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Re: [Emc-users] 3 d metal printer

[Valerio Bellizzomi]

On Wed, 2017-06-21 at 12:22 +0100, andy pugh wrote:
> On 20 May 2017 at 07:41, a k  wrote:
> 
> > hi
> > i found this
> > https://www.youtube.com/watch?v=wOarxQRKW9o
> > that is exactly that i try to build 4 years ago
> >
> 
> More of the same, plus some CGI to make it look like it actually works..
> 
> https://www.youtube.com/watch?v=n2szk5MItRA
> 
> It seems like it probably _will_ work in time.
> 
> Active magnetic weld-pool control? (Actually, that won't work due to the
> Curie point)
> 


3D concrete printing

https://www.youtube.com/watch?v=zb3zuk1qNDk




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Re: [Emc-users] following error only while homing

[Tom Easterday]

So is that large jump in f-error caused by the difference between 
axis.2.joint-pos-cmd and axis.2.joint-pos-fb?  There is a small 90 degree step 
in pos-cmd that is not mirrored in pos-fb near the end, in line with the spike 
of f-error.  Is that the cause and why is that there?

-Tom

> On Jun 20, 2017, at 8:54 PM, Tom Easterday  wrote:
> 
> Well, it has been homed and is searching for index when it faults with the 
> following errorbut it isn't homed as I have just killed and restarted 
> Linuxcnc.  I then move the Z axis down a little bit and then Home All...
> -Tom
> 
>> On Jun 20, 2017, at 7:54 PM, Peter C. Wallace  wrote:
>> 
>> This looks like it has been homed before (no large step in encoder position 
>> at index)
>> Peter Wallace
> 
> 
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Re: [Emc-users] following error only while homing

[Peter C. Wallace]

On Wed, 21 Jun 2017, Tom Easterday wrote:


Date: Wed, 21 Jun 2017 10:11:01 -0400
From: Tom Easterday 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: Re: [Emc-users] following error only while homing

So is that large jump in f-error caused by the difference between 
axis.2.joint-pos-cmd and axis.2.joint-pos-fb?  There is a small 90 degree 
step in pos-cmd that is not mirrored in pos-fb near the end, in line with 
the spike of f-error.  Is that the cause and why is that there?


Yes, and this is why you cannot do homing to index with a stepgen in position 
mode.


When you home to index the encoder position makes a (possibly large on first 
home after startup) step change when the index is detected. The commanded position
must make a matching step. With a servo system, this does not cause a major 
glitch because the commanded and feedback positions both change at once so

any move in progress just continues, in addition the PID component watches
index-enable so is able to discard the result of the derivative terms (FF1 and 
D) so they dont cause a thump.




This does not work with a stepgen in postion mode because the stepgen gets a 
step change in position command, that it cannot follow, this causes a large

instantaneous following error when index is detected


You can use step motors with an encoder and homing to index, but you must 
setup your hal file differently, running the stepgen in velocity mode and 
using a PID component to close the position loop with the feedback from the 
encoder




-Tom


On Jun 20, 2017, at 8:54 PM, Tom Easterday  wrote:

Well, it has been homed and is searching for index when it faults with the 
following errorbut it isn't homed as I have just killed and restarted 
Linuxcnc.  I then move the Z axis down a little bit and then Home All...
-Tom


On Jun 20, 2017, at 7:54 PM, Peter C. Wallace  wrote:

This looks like it has been homed before (no large step in encoder position at 
index)
Peter Wallace



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Peter Wallace
Mesa Electronics

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Re: [Emc-users] 3 d metal printer

[Nicklas Karlsson]

> 3D concrete printing
> 
> https://www.youtube.com/watch?v=zb3zuk1qNDk

Without rebar and vibration concrete will be weak, maybe it's good enough for a 
real firewall?

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Re: [Emc-users] following error only while homing

[Jon Elson]

On 06/20/2017 10:15 AM, Sebastian Kuzminsky wrote:

On 06/20/2017 08:52 AM, Chris Radek wrote:

On Tue, Jun 20, 2017 at 09:27:46AM +0100, andy pugh wrote:


Now, this is perfectly normal, and with a servo / pid 
machine the system
knows to ignore the f-error immediately after an encoder 
reset. What is
puzzling me here is why it isn't working in this case. I 
think it is


pid's index-enables need to be added to the index-enable 
nets.


Tom has no pids in this config, he's using position-mode 
steppers with encoders.



Where does the following error come from, then?

Jon

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Re: [Emc-users] following error only while homing

[Peter C. Wallace]

On Wed, 21 Jun 2017, Jon Elson wrote:


Date: Wed, 21 Jun 2017 11:48:17 -0500
From: Jon Elson 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: Re: [Emc-users] following error only while homing

On 06/20/2017 10:15 AM, Sebastian Kuzminsky wrote:

On 06/20/2017 08:52 AM, Chris Radek wrote:

On Tue, Jun 20, 2017 at 09:27:46AM +0100, andy pugh wrote:


Now, this is perfectly normal, and with a servo / pid machine the system
knows to ignore the f-error immediately after an encoder reset. What is
puzzling me here is why it isn't working in this case. I think it is


pid's index-enables need to be added to the index-enable nets.


Tom has no pids in this config, he's using position-mode steppers with 
encoders.



Where does the following error come from, then?

Jon


A step in the FB position from the encoder and an attempt at an impossible 
step in the commanded stepgen position...



All the complexities / workrounds of this position step on index could be 
avoided if support for encoder counter that can only clear on index 
was dropped.






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Peter Wallace
Mesa Electronics

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Re: [Emc-users] 3 d metal printer

[BRIAN GLACKIN]

The name "concrete" is misleading.  The paste is more of a grout using fine
aggregates whereas concrete typically has coarse aggregates.  With the
absence of coarse aggregates, the vibration requirement is minimized.  As
for reinforcement, simple paste as shown would be weak indeed unless they
are adding fibers to the mix (glass, polyester, metal are typical) which
would be likely in this case although not stated.  The "laminations" would
likely impart some strength as well.

As for fireproof, the structure has little in it (other than furnishings)
that would be combustible.

A final concern is the strength of the mix.  Typical cement mixes achieve
~15% of their strength in 24 hours (full strength in 28 days).  Again
additives or high early strength mixes could be used which could solve
that.  Either way, I would want the structure to fully "cure" prior to
moving in.  That means for me waiting a month no matter how fast they print
it.

I find the technology interesting and in certain circumstances could be
useful for developing structures in remote areas where transporting
pre-engineered structures and or components might be cost prohibitive.
Apic Cor has a video of them printing a "house" and how they reinforced and
insulated the structure for -35C conditions.  Kinda smallish but it can
easily be nested with other units to create office/work and or living
spaces.



On Wed, Jun 21, 2017 at 11:49 AM, Nicklas Karlsson <
nicklas.karlsso...@gmail.com> wrote:

> > 3D concrete printing
> >
> > https://www.youtube.com/watch?v=zb3zuk1qNDk
>
> Without rebar and vibration concrete will be weak, maybe it's good enough
> for a real firewall?
>
> 
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Re: [Emc-users] following error only while homing

[Jon Elson]

On 06/21/2017 12:15 PM, Peter C. Wallace wrote:


A step in the FB position from the encoder and an attempt 
at an impossible step in the commanded stepgen position...



All the complexities / workrounds of this position step on 
index could be avoided if support for encoder counter that 
can only clear on index was dropped.


OK, so stepgen also can compute following error.  Without 
encoders, it is only possible if steps can't be issued fast 
enough, but with encoders, then there are other ways to 
create a following error.


Thanks,

Jon

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Re: [Emc-users] following error only while homing

[Peter C. Wallace]

On Wed, 21 Jun 2017, Jon Elson wrote:


Date: Wed, 21 Jun 2017 13:22:04 -0500
From: Jon Elson 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: Re: [Emc-users] following error only while homing

On 06/21/2017 12:15 PM, Peter C. Wallace wrote:


A step in the FB position from the encoder and an attempt at an impossible 
step in the commanded stepgen position...



All the complexities / workrounds of this position step on index could be 
avoided if support for encoder counter that can only clear on index was 
dropped.


OK, so stepgen also can compute following error.  Without encoders, it is 
only possible if steps can't be issued fast enough, but with encoders, then 
there are other ways to create a following error.


Thanks,

Jon



The stepgen is not computing following error it just cant be driven by a 
position command with a stepwise discontinuity and move instantaneously to the 
new position.


A PID run velocity mode stepgen (or normal velocity mode servo) can do this 
because both its feedback (from the encoder) and the commanded position make 
this position step concurrently at index detection so the PID comp just 
carries on as if nothing had happened


The PID derivative terms, FF1 and maybe D are patched at index detection so 
the step in command and FB doesn't cause a one servo cycle long thump





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Peter Wallace
Mesa Electronics

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Re: [Emc-users] Mesa 7i47S issue

[Andrew]

2017-06-20 23:35 GMT+03:00 Peter C. Wallace :

>
>> This is not unexpected, the card is probably fine
>
> The 7I47S has differential inputs, They are not designed to interface with
> single ended signals but can if needed.
>
> The only way the inputs will work reliably is to have a positive
> differential voltage across the inputs in one case and a negative
> differential voltage in the other case.
>
> If you have single ended say 5V signals you wish to read what you can do
> is this:
>
> Make a low impedance voltage reference of 2.5V with 2 series 100 Ohm
> resistors from the 7I47S 5V pins.
>
> Connect this 2.5V reference to the inverted input pin of all the 7I47S
> inputs
> you wish to use, then connect your 5V single ended signals to the
> non-inverted inputs. Now when you input signal is 5V the input pair see
> +2.5V and when input signal is 0V, The input pair see -2.5V
>
> (this will only work with termination off)
>
>
Thanks a lot! I'll try that.

Like this, right?

​
​I think I better supply 5V to P1 in this case.

What is termination in this board? Simply a resistor across the input? What
is it for?

Thanks
Andrew
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[Emc-users] OT - handling a 120v ac dip

[kqt4at5v]

I am just a tinkerer so I'm looking for advice. I have a project using an 
ESP8266 to control a light. I am using a Panasonic AQY280EH to switch the 
light. What is the safe protocol for mounting and connecting a device that 
is using a high voltage.


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Re: [Emc-users] OT - handling a 120v ac dip

[Gene Heskett]

On Wednesday 21 June 2017 15:03:23 kqt4a...@gmail.com wrote:

> I am just a tinkerer so I'm looking for advice. I have a project using
> an ESP8266 to control a light. I am using a Panasonic AQY280EH to
> switch the light. What is the safe protocol for mounting and
> connecting a device that is using a high voltage.

One normally uses an opto-isolator to separate the computer from the high 
voltages in the external world.  Wire the + terminal of the led in the 
isolator, with a current limiting resistor to a 5 volt supply, and wire 
the - terminal of the led to the control output.  You want to "pull" 
the - terminal to a logic zero to turn on the led because thats the more 
capable direction in terms of the current needed to turn on the led.  
The other 2 terminals of the isolator are connected, aka "on" when the 
led shines on the other side, with a high voltage, usually up to 5,000 
volts, of isolation, between the two parts of the isolator.  And 
generally, when the led is energized, the circuit on the other side of 
the air gap will be too.

The output side may or may not be polarity sensitive, and if it is, will 
also have + and - markings.

You can get ready made kits for 1 or 4 on a board, of such devices from 
ebay for quite nominal prices.  I just wired up one channel of a 4 
channel I had in the spares drawer, to pull the RST terminal of the VFD 
running my lathes spindle down to its control ground so I didn't have to 
get a step-stool to reset it by hand in the event it faults.  A .4 
second reset pulse sent by the pi running things works fine.

Those generally are made for various input and output voltages, so you 
buy them accordingly. This one expects a 5 volt input, and controls the 
12 volt swing inputs of the VFD.  The VFD supplies the 12 volts needed, 
as well as its local ground/common. Unfortunately, those are common on 
this particular kit so I can't use it as 4 independent output channels.

Cheers, Gene Heskett
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-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] following error only while homing

[andy pugh]

On 21 June 2017 at 19:36, Peter C. Wallace  wrote:

> The stepgen is not computing following error it just cant be driven by a
> position command with a stepwise discontinuity and move instantaneously to
> the new position.


I think it might be more interesting than that. Stepgen commanded position
and encoder position track each other very well, and the f-error is small
throughout.

https://docs.google.com/spreadsheets/d/1qRVyQWFl4BIsSNKwy9IYsXrmZLTK8vgVVNX4tAuUmJM/edit?usp=sharing


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Re: [Emc-users] following error only while homing

[Peter C. Wallace]

On Thu, 22 Jun 2017, andy pugh wrote:


Date: Thu, 22 Jun 2017 00:06:42 +0100
From: andy pugh 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: Re: [Emc-users] following error only while homing

On 21 June 2017 at 19:36, Peter C. Wallace  wrote:



The stepgen is not computing following error it just cant be driven by a
position command with a stepwise discontinuity and move instantaneously to
the new position.



I think it might be more interesting than that. Stepgen commanded position
and encoder position track each other very well, and the f-error is small
throughout.

https://docs.google.com/spreadsheets/d/1qRVyQWFl4BIsSNKwy9IYsXrmZLTK8vgVVNX4tAuUmJM/edit?usp=sharing


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"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, 1916


Only because the step was small (because it was probably not the first time 
homed)


Take a look at axis.0.motor-pos-fb and axis.0.motor-pos-cmd in Sebastians test
on a servo system:

http://highlab.com/~seb/linuxcnc/homing-x-first-time.png

Notice the (probably multi-inch) jump to 0 when index is detected

A velocity mode servo system can cope with this because the PIDs command and 
feedback step at the ~same time (and there are some patches to fix derivative 
related problems in the PID comp when index is detected)


Peter Wallace
Mesa Electronics

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Re: [Emc-users] following error only while homing

[Tom Easterday]

I moved the Z axis down maybe 1/2" before issuing the home command, so it only 
needs to move a short distance to get back to the switch.
-Tom

> On Jun 21, 2017, at 7:19 PM, Peter C. Wallace  wrote:
> 
> Only because the step was small (because it was probably not the first time 
> homed)


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Re: [Emc-users] OT - handling a 120v ac dip

[Ralph Stirling]

The AQY280EH is optically isolated, but can only switch a low current load 
(130mA).  If you are switching a 60w bulb, you would need a several amp device 
to handle the in-rush current of a cold bulb.  I like to wire a "puck" type 
solid state relay (ssr) into an old metal outlet strip (that can be opened up, 
and that has room inside) or into a 4x4 metal junction box with a receptacle 
and cord.  A couple of small wires can be brought out for the low voltage 
control.

If you need more detail, I can dig up some example ssr part numbers and sketch 
out the simple circuit for you.

-- Ralph

On Jun 21, 2017 12:03 PM, kqt4a...@gmail.com wrote:
I am just a tinkerer so I'm looking for advice. I have a project using an
ESP8266 to control a light. I am using a Panasonic AQY280EH to switch the
light. What is the safe protocol for mounting and connecting a device that
is using a high voltage.

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