[Emc-users] Running PathPilot on non-Tormach Machines

[Ron Ginger]

I would like to try to run PathPilot on my own mill. I now run Mach4, 
but I would like to see how well PathPilot works.


I see I can simply download a copy from the Tormach site.  what 
interface board do I need?


What is Tormachs position on this? I know they have to release the code 
because it is based on open source, but do they oppose its use?


thanks

ron ginger


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Re: [Emc-users] Linuxcnc debs for RPi4

[Chris Albertson]

>
> Why would anyone care about the latest Linux version?


Perhaps the computer is used for multiple purposes and other software is
run on the computer.   I only have one PC in the shop and it is used for
both milling and 3D printing.  It also runs a web interface for remote
operation of the printers and has a couple of USB webcams and
live-streams video, so I can check if stuff is working.   I'm lucky in that
I got it all to run on the same Linux version.

The other harder case is if someone wanted to use LCNC for a
robot controller.   You can think of a robot as a (maybe) 6-axis or 14-axis
machine where all the motors need to run in synchronized motion, and you
might try to use LCNC.   I think this is a reasonable idea for a large
industrial factory automation robot.In this case, there is a ton of
other software involved for things like real-time path planning and 3D
computer vision and whatnot, and it all needs to run on the same version of
Linux.  Actually, some people are doing this (with machine kit, I think)

After you put multiple software on the same PC and then get it to work, the
real problem is if the "latest" version of one part requires the latest
Linux version, and you need to upgrade to fix a bug.   The solution is
"docker" or virtual machines.  You end up running multiple copies of
Linux.   This is inefficient, but sometimes the only way.
-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] ot: change ps 613u pots

[gene heskett]

On 1/22/23 18:15, fxkl47BF--- via Emc-users wrote:

On Sun, 22 Jan 2023, gene heskett wrote:


On 1/22/23 04:19, fxkl47BF--- via Emc-users wrote:

On Sat, 21 Jan 2023, gene heskett wrote:


On 1/21/23 20:23, fxkl47BF--- via Emc-users wrote:

i acquired a non-working ps 613u power supply
two 2200uf caps had exploded
i replaced them and it appears to be working
my complaint is the voltage and current pots are very sensitive
it's near impossible to adjust them with any precision
i'm thinking to replace them with multi-turn pots
is this a good idea or a waste of time

https://www.velleman.eu/downloads/2/ps613a502.pdf


The caps exploded? On your bench or sometime in the past?


that's how it was when i got it


So you don't know the history. As a CET my best guess in that case would
be that its a 125 volt unit, accidentally plugged into a 250 VAC circuit
and turned on. What size is the fuse supposed to be? It should have
cleared before the explosions of the caps. There might be other failures
in the aftermath. input rectifiers need checked, So would the switching
transistors in the power circuit. Once you think you've found and
replaced the obvious stuff. I'd fire it up on a powerstat set for 50% or
60 VAC, and raise it slowly over several hours to normal input voltage
while scanning it with an IR thermometer looking for other hot components.

This is a CET's SWAG, so plz report what you find.


after i replaced the caps i fired it up
the fuse was not blown


But was it the right size?


it works as advertised but is very difficult to adjust


Some contact cleaner sprayed in the pots if open enough to get the spray 
inside might be in order. If room behind the pots for the helipots 
length, a replacement might be worth the cost.  Those I've used have 
been pretty stable.






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.


Cheers, Gene Heskett.
--
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] Linuxcnc debs for RPi4

[gene heskett]

On 1/22/23 18:04, John Dammeyer wrote:

From: Bari [mailto:bari00...@gmail.com]

On 1/22/23 15:25, John Dammeyer wrote:


Why would anyone care about the latest Linux version?The fundamental 
operation of LinuxCNC is read a

G-Code file and send out the information for motion.  Read back feedback from 
motion.  Display path on
screen.


Why in the world would Bullseye be important or even needed?



Compatibility between LCNC version and the applications called on in a
version of Debian. An example might be the version of Python required
for a LCNC GUI.


I'm not so sure about that.  The scenario I see is I installed LCNC on my Pi4.  
Whatever distribution was available. Now for me it's still a lab  bench play 
thing but in addition to LCNC I also installed Lazarus and it came with Python 
etc.

Now.  Say it was connected to real hardware.  At what point do I need to redo 
the LCNC user interface GUI if I'm just using it the same way as I did 2 years 
ago.

I mention all this only because a number of years ago I installed OctoPi on a 
Pi2 for my 3D printer.  Like a fool at one point, although absolutely nothing 
was wrong, I clicked on update.

System crashed big time.  Lost all my configuration information.  Had to in 
essence start over.  My complaint to the author of OctoPi was met with the 
usual surly Linux user attitude.  That it was my fault.  I should keep my OS up 
to date.

My response was twofold.  First my answer is the installation should check to 
see if the OS it's running on is either new enough or if this installation has 
been tested on this OS.  If not.  Pop up a message that the OS needs upgrading 
first.

My second response was to remove the funding I was sending monthly.  That was 4 
years ago.  The 3D printer still works.  OctoPi still works.  G-Code is still 
turned into plastic.

To sum up, when OS/Program vendors/suppliers upgrade they rarely if ever have to pay 
costs the end users absorb for this new and wonderful change to "enhance their user 
experience".

So quite frankly I don't care if Bullseye never makes it to the Pi4.  Way too 
expensive use of my time to go through an upgrade process.

John


I am running master on everything, right straight from the buildbot, 
that includes my one and only rpi4 running master to run a sheldon 
lathe, everything is still on buster, or the raspios version of buster.


The last time I had the rpi4 booted to bullseye, the python was too new 
for linuxcnc. I put the buster SD card back into it. And I've not 
retried it recently... Its working just fine on buster. Until buster is 
plumb out of support, I'm not worrying about it.


I just updated it from the buildbot, runs fine after.

From a login on the pi:
pi@rpi4:~/linuxcnc/configs/sheldon-lathe $ sudo apt update && sudo apt 
upgrade -y && sudo apt autoremove

Get:1 http://buildbot.linuxcnc.org buster InRelease [45.0 kB]
Get:2 http://buildbot.linuxcnc.org buster/master-rtpreempt armhf 
Packages [129 kB]

Fetched 174 kB in 2s (95.7 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
4 packages can be upgraded. Run 'apt list --upgradable' to see them.
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
  linuxcnc-doc-en linuxcnc-uspace linuxcnc-uspace-dbgsym 
linuxcnc-uspace-dev

4 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 60.3 MB of archives.
After this operation, 57.3 kB of additional disk space will be used.
Get:1 http://buildbot.linuxcnc.org buster/master-rtpreempt armhf 
linuxcnc-uspace-dev armhf 1:2.10.0~pre0.671.ge82d11060 [302 kB]
Get:2 http://buildbot.linuxcnc.org buster/master-rtpreempt armhf 
linuxcnc-uspace-dbgsym armhf 1:2.10.0~pre0.671.ge82d11060 [12.3 MB]
Get:3 http://buildbot.linuxcnc.org buster/master-rtpreempt armhf 
linuxcnc-doc-en all 1:2.10.0~pre0.671.ge82d11060 [26.4 MB] 

Get:4 http://buildbot.linuxcnc.org buster/master-rtpreempt armhf 
linuxcnc-uspace armhf 1:2.10.0~pre0.671.ge82d11060 [21.3 MB] 

Fetched 60.3 MB in 1min 3s (963 kB/s) 



apt-listchanges: Reading changelogs...
(Reading database ... 428454 files and directories currently installed.)
Preparing to unpack 
.../linuxcnc-uspace-dev_1%3a2.10.0~pre0.671.ge82d11060_armhf.deb ...
Unpacking linuxcnc-uspace-dev (1:2.10.0~pre0.671.ge82d11060) over 
(1:2.10.0~pre0.577.g603e106b4) ...
Preparing to unpack 
.../linuxcnc-uspace-dbgsym_1%3a2.10.0~pre0.671.ge82d11060_armhf.deb ...
Unpacking linuxcnc-uspace-dbgsym (1:2.10.0~pre0.671.ge82d11060) over 
(1:2.10.0~pre0.577.g603e106b4) ...
Preparing to unpack 
.../linuxcnc-doc-en_1%3a2.10.0~pre0.671.ge82d11060_all.deb ...
Unpacking linuxcnc-doc-en (1:2.10.0~pre0.671.ge82d11060) over 
(1:2.10.0~pre0.577.g603e106b4) ...
Preparing to unpack 
.../linuxcnc-uspace_1%3a2.10.0~pre0.671.ge82d11060_armhf.deb ...
Unpacking linuxcnc-uspace (1:2.10.0~pre0.671.ge82d11060) over 

Re: [Emc-users] ot: change ps 613u pots

[fxkl47BF--- via Emc-users]

On Sun, 22 Jan 2023, gene heskett wrote:

> On 1/22/23 04:19, fxkl47BF--- via Emc-users wrote:
>> On Sat, 21 Jan 2023, gene heskett wrote:
>>
>>> On 1/21/23 20:23, fxkl47BF--- via Emc-users wrote:
 i acquired a non-working ps 613u power supply
 two 2200uf caps had exploded
 i replaced them and it appears to be working
 my complaint is the voltage and current pots are very sensitive
 it's near impossible to adjust them with any precision
 i'm thinking to replace them with multi-turn pots
 is this a good idea or a waste of time

 https://www.velleman.eu/downloads/2/ps613a502.pdf

>>> The caps exploded? On your bench or sometime in the past?
>>
>> that's how it was when i got it
>
> So you don't know the history. As a CET my best guess in that case would
> be that its a 125 volt unit, accidentally plugged into a 250 VAC circuit
> and turned on. What size is the fuse supposed to be? It should have
> cleared before the explosions of the caps. There might be other failures
> in the aftermath. input rectifiers need checked, So would the switching
> transistors in the power circuit. Once you think you've found and
> replaced the obvious stuff. I'd fire it up on a powerstat set for 50% or
> 60 VAC, and raise it slowly over several hours to normal input voltage
> while scanning it with an IR thermometer looking for other hot components.
>
> This is a CET's SWAG, so plz report what you find.

after i replaced the caps i fired it up
the fuse was not blown
it works as advertised but is very difficult to adjust



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Re: [Emc-users] Linuxcnc debs for RPi4

[John Dammeyer]

> From: Bari [mailto:bari00...@gmail.com]
> 
> On 1/22/23 15:25, John Dammeyer wrote:
> 
> > Why would anyone care about the latest Linux version?The fundamental 
> > operation of LinuxCNC is read a
> G-Code file and send out the information for motion.  Read back feedback from 
> motion.  Display path on
> screen.
> >
> > Why in the world would Bullseye be important or even needed?
> 
> 
> Compatibility between LCNC version and the applications called on in a
> version of Debian. An example might be the version of Python required
> for a LCNC GUI.
> 
I'm not so sure about that.  The scenario I see is I installed LCNC on my Pi4.  
Whatever distribution was available. Now for me it's still a lab  bench play 
thing but in addition to LCNC I also installed Lazarus and it came with Python 
etc.

Now.  Say it was connected to real hardware.  At what point do I need to redo 
the LCNC user interface GUI if I'm just using it the same way as I did 2 years 
ago.

I mention all this only because a number of years ago I installed OctoPi on a 
Pi2 for my 3D printer.  Like a fool at one point, although absolutely nothing 
was wrong, I clicked on update.  

System crashed big time.  Lost all my configuration information.  Had to in 
essence start over.  My complaint to the author of OctoPi was met with the 
usual surly Linux user attitude.  That it was my fault.  I should keep my OS up 
to date.

My response was twofold.  First my answer is the installation should check to 
see if the OS it's running on is either new enough or if this installation has 
been tested on this OS.  If not.  Pop up a message that the OS needs upgrading 
first.

My second response was to remove the funding I was sending monthly.  That was 4 
years ago.  The 3D printer still works.  OctoPi still works.  G-Code is still 
turned into plastic.

To sum up, when OS/Program vendors/suppliers upgrade they rarely if ever have 
to pay costs the end users absorb for this new and wonderful change to "enhance 
their user experience".

So quite frankly I don't care if Bullseye never makes it to the Pi4.  Way too 
expensive use of my time to go through an upgrade process.

John




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Re: [Emc-users] Linuxcnc debs for RPi4

[Bari]

On 1/22/23 15:25, John Dammeyer wrote:


Why would anyone care about the latest Linux version?The fundamental 
operation of LinuxCNC is read a G-Code file and send out the information for 
motion.  Read back feedback from motion.  Display path on screen.

Why in the world would Bullseye be important or even needed?



Compatibility between LCNC version and the applications called on in a 
version of Debian. An example might be the version of Python required 
for a LCNC GUI.




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Re: [Emc-users] Linuxcnc debs for RPi4

[John Dammeyer]

> From: Sebastian Kuzminsky [mailto:s...@highlab.com]
> 
> On 1/22/23 12:30, Alan Condit wrote:
> > Does any one have debs for installing linuxcnc for Raspberry Pi4 on Debian
> > Bullseye?
> 
> We don't currently build that platform.
> 
> Adding it would require new hardware in the buildbot: at least one
> additional Raspberry Pi 4B, which is hard to find these days.
> 
> 
> --
> Sebastian Kuzminsky
> 

This is maybe a dumb question.  Given that we are talking about running 
LinuxCNC,  that means some sort of external step/dir interface like a MESA via 
Ethernet in order to get enough I/O.

Why would anyone care about the latest Linux version?The fundamental 
operation of LinuxCNC is read a G-Code file and send out the information for 
motion.  Read back feedback from motion.  Display path on screen.

Why in the world would Bullseye be important or even needed?

John



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Re: [Emc-users] Resolvers and 2 phase AC servos

[gene heskett]

On 1/22/23 04:54, Robin Szemeti via Emc-users wrote:

Yep, I have used steppers, servos, optical encoders with EMC etc etc in the
past, however, on this particular device, I am not going to try and hack
the mechanicals apart to start changing stuff. It's a high quality bit of
military kit that has presumably worked well enough in its previous life,
it just needs some suitable control system putting on it.  I've been
running stuff on EMC for decades as you probably know, so yeah, I know what
it can do. As it stands, it is fully waterproof, with all stainless or
aluminium parts (yes, I am aware of the issues mixing stainless and
aluminium) and the highest quality waterproof Amphenol connectors, I hope
to be able to leave it as it is.

A 2 pole resolver will typically be good to 5 minutes of arc, these on here
are some of the nicest I have seen, the military are not known for cheaping
out on their kit!  I fully expect them to acheive that level off accuracy
with the Mesa board.



Touche`. That is about the accuracy I'm getting with a clone BS-1 I 
CNC'd a year ago. Worm in the encoded gate motor into worm drive in the 
BS-1.  Too slow for active machining unless EDM'ing something. Great for 
holding tools at add angles to sharpen them with a CBN wheel. Also too 
heavy and too tall for my G0704 to carry comfortably.  Should have 
started with a BS-0.


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, 1940)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 



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Re: [Emc-users] ot: change ps 613u pots

[gene heskett]

On 1/22/23 04:19, fxkl47BF--- via Emc-users wrote:

On Sat, 21 Jan 2023, gene heskett wrote:


On 1/21/23 20:23, fxkl47BF--- via Emc-users wrote:

i acquired a non-working ps 613u power supply
two 2200uf caps had exploded
i replaced them and it appears to be working
my complaint is the voltage and current pots are very sensitive
it's near impossible to adjust them with any precision
i'm thinking to replace them with multi-turn pots
is this a good idea or a waste of time

https://www.velleman.eu/downloads/2/ps613a502.pdf


The caps exploded? On your bench or sometime in the past?


that's how it was when i got it


So you don't know the history. As a CET my best guess in that case would 
be that its a 125 volt unit, accidentally plugged into a 250 VAC circuit 
and turned on. What size is the fuse supposed to be? It should have 
cleared before the explosions of the caps. There might be other failures 
in the aftermath. input rectifiers need checked, So would the switching 
transistors in the power circuit. Once you think you've found and 
replaced the obvious stuff. I'd fire it up on a powerstat set for 50% or 
60 VAC, and raise it slowly over several hours to normal input voltage 
while scanning it with an IR thermometer looking for other hot components.


This is a CET's SWAG, so plz report what you find.

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, 1940)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 



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Re: [Emc-users] Linuxcnc debs for RPi4

[Sebastian Kuzminsky]

On 1/22/23 12:30, Alan Condit wrote:

Does any one have debs for installing linuxcnc for Raspberry Pi4 on Debian
Bullseye?


We don't currently build that platform.

Adding it would require new hardware in the buildbot: at least one 
additional Raspberry Pi 4B, which is hard to find these days.



--
Sebastian Kuzminsky



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[Emc-users] Linuxcnc debs for RPi4

[Alan Condit]

Does any one have debs for installing linuxcnc for Raspberry Pi4 on Debian
Bullseye?
Alan

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Re: [Emc-users] Resolvers and 2 phase AC servos

[Robin Szemeti via Emc-users]

Yep, I'm planning to use the Mesa resolver boards, simply because I already
have a fair bit of Mesa kit.   I expect resolution to be 14 bits and
accuracy to be 12 bits.

On Sun, 22 Jan 2023 at 16:52, Jon Elson  wrote:

> On 1/21/23 19:34, Robin Szemeti via Emc-users wrote:
> > One thing that might cause some ... well, "issues" is my resolvers are
> used
> > to determine the absolute angular position of my two rotational axes, ie
> > they are driven off the axes themselves after the gearing, not off the
> > motors before the gearing. This may prove to be a bit "interesting" ..
> but
> > since my desired movement is very slow, fractions of a degree per
> minute, I
> > suspect it is not going to be a problem and it can all be handled in a
> slow
> > task loop.
> >
> The resolver boards I make deliver 4096 quadrature counts
> for one full rev, and they do not dither when standing still.
>
> So, that is better than 1/10th of a degree.  Some other
> resolver converters can do even finer resolution.
>
> Jon
>
>
>
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Re: [Emc-users] Resolvers and 2 phase AC servos

[Nicklas SB Karlsson]

sön 2023-01-22 klockan 10:51 -0600 skrev Jon Elson:
> On 1/21/23 19:34, Robin Szemeti via Emc-users wrote:
> > One thing that might cause some ... well, "issues" is my resolvers
> > are used
> > to determine the absolute angular position of my two rotational
> > axes, ie
> > they are driven off the axes themselves after the gearing, not off
> > the
> > motors before the gearing. This may prove to be a bit "interesting"
> > .. but
> > since my desired movement is very slow, fractions of a degree per
> > minute, I
> > suspect it is not going to be a problem and it can all be handled
> > in a slow
> > task loop.
> > 
> The resolver boards I make deliver 4096 quadrature counts 
> for one full rev, and they do not dither when standing still.
> 
> So, that is better than 1/10th of a degree.  Some other 
> resolver converters can do even finer resolution.
Up to 16 bit resolution though there is a choice between resolution and
response time.

Nicklas Karlsson



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Re: [Emc-users] Resolvers and 2 phase AC servos

[Jon Elson]

On 1/21/23 19:34, Robin Szemeti via Emc-users wrote:

One thing that might cause some ... well, "issues" is my resolvers are used
to determine the absolute angular position of my two rotational axes, ie
they are driven off the axes themselves after the gearing, not off the
motors before the gearing. This may prove to be a bit "interesting" .. but
since my desired movement is very slow, fractions of a degree per minute, I
suspect it is not going to be a problem and it can all be handled in a slow
task loop.

The resolver boards I make deliver 4096 quadrature counts 
for one full rev, and they do not dither when standing still.


So, that is better than 1/10th of a degree.  Some other 
resolver converters can do even finer resolution.


Jon



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Re: [Emc-users] Resolvers and 2 phase AC servos

[Robin Szemeti via Emc-users]

Hi Chris,

An interesting device, but you are making a fundamental mistake in
confusing resolution with accuracy.  If you read the datasheet, they make
no claims whatsoever about accuracy, if it was good, I am sure they would
mention it. That said, I would reasonably expect them to achieve +- 5
degrees of accuracy,  maybe better, and yes, I appreciate they have a much
higher resolution.

A good 2 pole resolver will achieve 5' of accuracy (that's 1/12th of a
degree), resolution will be limited to the resolution of the ADC's reading
the signals. Being an AC device it is relatively immune to the earths
magnetic field. The devices I have are fully waterproof high quality
resolvers costing probably thousands of dollars each ... I think I'll stick
with them.

On Sun, 22 Jan 2023 at 01:35, Chris Albertson 
wrote:

> You can simplify this if you replace the resolvers with magnetic encoders.
> They cost $4 each and come  mounted to PCBs and with a magnet.   What you
> do is super-glue the magnet to the shaft end and then face the chip at the
> magnet with an about 1mm air gap.  The chip tells you the shaft angle to
> within 1/4000 of a revolution.It is easy because it is an absolute
> encoder so you don't have to track the shaft you can query the angle
> whenever you need it.  There is both an analog and digital output
>
> It is a 4mm diameter magnet and you mount it by first making a small hole
> in the shaft with a drill if the shaft is not already center drilled.  Then
> the magnet is very powerful and you really don't need glue.  They work
> better if you get larger 6mm dia. magnets but still I get reading good to
> about 0.1 degree.
>
> With resolvers and quadrature encoders you have to track the encoders
> continuously but these are "query on demand."   With more money, for $10
> you get a better sensor that does 16,000 "ticks" per revolution, absolute.
> These are cheap enough to place them on the motor and the driven structure
> https://www.amazon.com/HiLetgo-Magnetic-Encoder-Measurement-Precision/
> <
> https://www.amazon.com/HiLetgo-Magnetic-Encoder-Measurement-Precision/dp/B09KGWC1PT/ref=sr_1_2_sspa?keywords=as5600=1674349813=8-2-spons=1=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzOThLWTdPUkkyWlpCJmVuY3J5cHRlZElkPUEwMjg2NTczMjVSOVNEOU1aTDFEUCZlbmNyeXB0ZWRBZElkPUEwMzE1MDEwMk5UUjVRNlJINkhRQiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=
> >
>
> On Sat, Jan 21, 2023 at 4:59 PM gene heskett  wrote:
>
> > On 1/21/23 06:25, Robin Szemeti via Emc-users wrote:
> > > So,  in a vaguely CNC related folly I have purchased a 2 axis military
> > dish
> > > mount for radio stuff (moonbounce, if you must know)
> > >
> > > My plan is to control it from EMC, with a Mesa anything io card and the
> > > resolver interface, I already have various Mesa cards under EMC, so
> thats
> > > not an issue and I have a spare 5i23 PCI card and the isolated IO
> > duaghter
> > > card, so with the resolver card I should be able to uses the resolvers,
> > and
> > > pick up the limit switches on the IO card. I can just use some Python
> > > script to work out the moon position and generate "G1 X285.4, Y23.8" or
> > > whatever MDI motion commands every 15 seconds or so to track the moon,
> > not
> > > a problem.
> > >
> > > Now, the question is driving the two phase AC servos.   Generating vast
> > > quantities of 50 or 400Hz or whatever AC for the drives is simple
> > enough, I
> > > can just use a couple of large Class D amplifiers, no worries.
> Generating
> > > the AC low level signals to drive these  basically, it needs a
> > constant
> > > 50Hz signal on one coil of a fixed level, and a variable level sine
> wave
> > on
> > > the other coil, at either +90 or -90 degrees depending on which way it
> > > needs to go.
> > >
> > > Is it possible to use HAL or something to generate the variable level
> > 50Hz
> > > servo drive signals and output them from the PWM outputs on the
> resolver
> > > card?
> > >
> > I've not used it in that context, but take a look at man 9 siggen.
> > There are several mux's available that could be used to switch motor
> > directions. Its main use is in 1 kilohertz loop stuff for linuxcnc, but
> > if you need finer time resolution, should be happy in a 3 to 5 kilohertz
> > threads Use a halmeter to see how much time the individual module takes.
> >
> > Hal can do a lot, look the logic choices over in /usr/share/man/man9 of
> > an linuxcnc install and let your imagination out to play w/o a
> > chaperone.  You can use float vars at a 1 or even 4 kilohertz loop
> > thread, so updating a motor drive at 50HZ ought to be doable.
> >
> > For motor amps, take a look at class D audio amps, the 400 watt modules
> > are rather commonplace these days, running at ultrasonic carrier
> > frequencies. Use chokes to keep the carrier out of the motor wires, and
> > good single point(one bolt) grounds.
> >
> > Use mux's for analog switches.
> >
> > Using modern stepper drives that have current limits built 

Re: [Emc-users] Resolvers and 2 phase AC servos

[Robin Szemeti via Emc-users]

Yep, I have used steppers, servos, optical encoders with EMC etc etc in the
past, however, on this particular device, I am not going to try and hack
the mechanicals apart to start changing stuff. It's a high quality bit of
military kit that has presumably worked well enough in its previous life,
it just needs some suitable control system putting on it.  I've been
running stuff on EMC for decades as you probably know, so yeah, I know what
it can do. As it stands, it is fully waterproof, with all stainless or
aluminium parts (yes, I am aware of the issues mixing stainless and
aluminium) and the highest quality waterproof Amphenol connectors, I hope
to be able to leave it as it is.

A 2 pole resolver will typically be good to 5 minutes of arc, these on here
are some of the nicest I have seen, the military are not known for cheaping
out on their kit!  I fully expect them to acheive that level off accuracy
with the Mesa board.

On Sun, 22 Jan 2023 at 03:21, gene heskett  wrote:

> On 1/21/23 20:20, Robin Szemeti via Emc-users wrote:
> > That looks like a useful module ... sine for one of the coils, cosine for
> > the other, and simply multiply the cosine signal by the servo drive
> signal
> > +1 goes one direction, -1 goes the other and anything in between is just
> > slower ...
> >
> > I have a company that manufactures audio amps, driver stages won't be a
> > problem.
> >
> > Just got to do some testing of the resolvers and decide which version of
> > the Mesa hard to order, I think these resolvers output 2 x the input
> > voltage, so I probably need the HV version, but we'll see.
> >
> > This will be used on the 10GHz band, with about 400W from a travelling
> wave
> > tube  there are good Python modules for moon position data,
> 'skyfield'
> > is the best of the bunch, I need roughly +- 1 degree precision, with
> just a
> > position update every 30 seconds or so .. the move doesnt move that
> fast. A
> > good resolver should easily be able to get within 0.5 degrees ...
> >
> > I'll let you know how it pans out.
>
> One of the reasons I mentioned the stepper/servo is that with its
> builtin encoder telling it where it is, the error signal is then used as
> the current control to the motor. It gives two characteristics to the
> control, the first being its accuracy in terms of rotational precision
> can be just one or two counts of the encoder, which in even the bargain
> basement models has about 14 bits of resolution per full turn of the
> motors armature. Such is the tech today, where a nema17 motor with a42
> mm thick core, develops nominally .5NM at a max rpm of about 1000,
> drives with the normal step/dir signals,and sells for about $40 a copy
> on amazon.  Needs 24 to 28 volts, and about 2 amps when working hard,
> microsteps to 256, we normally run them at 16, meaning 16 steps either
> way are one full steps move. That $5 arduino can drive them. They would
> need weather protection, but what doesn't. First stage geardown would be
> a 20 tooth gt2 pulley and 6mm wide belt turning a 150mm diameter pulley,
> which would drive another chain drive with #35 chain. Big 3 layers of
> plywood for the final pulley.  Or drive the screw in a long sat jack
> from Venture mfg in Dayton OH, but that would involve correcting for the
> non-linearity, and a full 180 scan is at best impractical.
>
> The other just as huge advantage is if it hits a stop and can't get to a
> +-2 counts or so balance between where it was told to go vs where it is,
> and if that is violated for any great amount of time, it will close a
> circuit, stopping linuxcnc in its tracks. I can on my 11x54" 80 yo
> sheldon lathe, position a jaw so the tool chip will hit the jaw, issue a
> move at an 1nch a second causing the tool's chip to hit the chuck jaw,
> It runs to hit the jaw, see's the stop, and kills linuxcnc in about a
> millisecond. The carbide chip in the tool is not damaged, nor is the
> chuck jaw marked.
>
> The mks-servo42C OTOH will blow its drivers if it can't get there.
>
> Yet that has never actually happened while doing real work. The original
> 2 phase steppers, they ran at a constant current when moving and half
> current standing still so they ran just short of burn your hand hot.
>
> Now these run maybe 10F above ambient unless working really hard at high
> speeds, a considerable power savings.
>
> [snip]
>
> Take care & stay well, Robin.
>
> 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, 1940)
> If we desire respect for the law, we must first make the law respectable.
>   - Louis D. Brandeis
> Genes Web page 
>
>
>
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>

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Re: [Emc-users] ot: change ps 613u pots

[fxkl47BF--- via Emc-users]

On Sat, 21 Jan 2023, gene heskett wrote:

> On 1/21/23 20:23, fxkl47BF--- via Emc-users wrote:
>> i acquired a non-working ps 613u power supply
>> two 2200uf caps had exploded
>> i replaced them and it appears to be working
>> my complaint is the voltage and current pots are very sensitive
>> it's near impossible to adjust them with any precision
>> i'm thinking to replace them with multi-turn pots
>> is this a good idea or a waste of time
>>
>> https://www.velleman.eu/downloads/2/ps613a502.pdf
>>
> The caps exploded? On your bench or sometime in the past?

that's how it was when i got it___
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