Re: [Emc-users] Rough motion with servos

[Jon Elson]

On 06/27/2017 03:06 PM, Les Newell wrote:
Hmm, looks like that was a red herring. The problem is 
back. I can't do any more testing because the pixies 
inside the old computer finally abandoned ship and it now 
no longer boots. Doesn't even post. My priority now is 
going to be to find a box that will run my old EMC.


Whenever this happens, I reseat the memory sticks and maybe 
even the CPU and that often brings it back.

Of course, it could have suffered the capacitor plague.

Jon

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Re: [Emc-users] Encoder

[Gene Heskett]

On Tuesday 27 June 2017 15:45:20 dave wrote:

> On 06/27/2017 12:09 PM, Gene Heskett wrote:
> > On Tuesday 27 June 2017 14:56:25 dave wrote:
> >> Hi,
> >> The bad news is that my spare Koyo encoder is toast, why I don't
> >> know. Apparently happened a while
> >> ago and I didn't label it; sloppy on my part.
> >> Checked X axis with another encoder I swiped off the lathe and got
> >> reasonable counts.
> >> Now to order a couple of spares.
> >>
> >> However, I have this thru-shaft encoder I must have picked up
> >> surplus somewhere.
> >
> > How big is the thru shaft? I might have a home for it. I about 7/8"
> > of shaft out the rear of my x motor that I've not sawed off yet.
> > 6.35mm shaft.
> >
> >> Sumtek LHF-078-5000. Best I can tell it is 5000 ppr max freq of 250
> >> KHz. Voltage, pin out and
> >> output unknown except for being marked A, B, Z. Connector is a 3 x
> >> 3 with 7 used.
> >> Apparently the output is a line driver.  Probably not worth fooling
> >> with but interesting.
> >>
> >> Dave
> >
> > Cheers, Gene Heskett
>
> Looks to be .5"
> Dave

PM me if there is a shaft adapter available, and a quote so I can see if 
I can afford it. How deep behind a nema /24/ motor would it be?

Thanks Dave
>
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Cheers, Gene Heskett
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Re: [Emc-users] Rough motion with servos

[Les Newell]

Hmm, looks like that was a red herring. The problem is back. I can't do 
any more testing because the pixies inside the old computer finally 
abandoned ship and it now no longer boots. Doesn't even post. My 
priority now is going to be to find a box that will run my old EMC.


Les



On 27/06/17 19:50, Les Newell wrote:


150 uS??  YIKES!  That is not generally good enough for even a servo 
system


I have done a lot of work with PID loops in various non LinuxCNC 
systems and in my general experience they generally seem to be very 
tolerant to timing variation. After all we are dealing with motors 
that have a bandwidth far lower than the PID loop speed. Anyway I have 
two boxes here so I can run back-to-back tests at some point.


I think I may have found the problem. Pncconf doesn't connect 
pid.n.feedback-deriv to the encoder velocity. The version of EMC I am 
running doesn't have feedback-deriv so my config doesn't either. With 
no connection, pid estimates the derivative and something funky is 
going on with that estimation. Sometimes the machine twitches while 
stationary which makes it a lot easier to see what is going on. 
Watching feedback-deriv on halscope I can see it move at exactly the 
same moment as the output jumps. A few milliseconds later the encoder 
velocity moves in response.


After connecting the encoder velocity to feedback-deriv my tuning 
values have to be very different but the twitching appears to have 
gone away. The tuning at the moment is very rough with just P,D and FF 
used. I need to experiment further and tune the axis properly before 
saying the problem is definitely fixed. Now I need to try to figure 
out why my jogwheels (one per axis) don't work.


Is there a reason why Pncconf doesn't connect the encoder velocity? By 
the way Pncconf wouldn't let me set the maximum feed rate to more than 
2000mm/min which is a bit annoying as the machine is capable of 4800.


Les




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Re: [Emc-users] Encoder

[dave]

On 06/27/2017 12:09 PM, Gene Heskett wrote:

On Tuesday 27 June 2017 14:56:25 dave wrote:


Hi,
The bad news is that my spare Koyo encoder is toast, why I don't know.
Apparently happened a while
ago and I didn't label it; sloppy on my part.
Checked X axis with another encoder I swiped off the lathe and got
reasonable counts.
Now to order a couple of spares.

However, I have this thru-shaft encoder I must have picked up surplus
somewhere.

How big is the thru shaft? I might have a home for it. I about 7/8" of
shaft out the rear of my x motor that I've not sawed off yet. 6.35mm
shaft.


Sumtek LHF-078-5000. Best I can tell it is 5000 ppr max freq of 250
KHz. Voltage, pin out and
output unknown except for being marked A, B, Z. Connector is a 3 x 3
with 7 used.
Apparently the output is a line driver.  Probably not worth fooling
with but interesting.

Dave





Cheers, Gene Heskett

Looks to be .5"
Dave


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Re: [Emc-users] Nurbs question

[Gene Heskett]

On Tuesday 27 June 2017 15:07:51 andy pugh wrote:

> On 27 June 2017 at 18:59, Gene Heskett  wrote:
> > I've not noted any great amount of mention of nurbs on the list, and
> > I am wondering how usable it is in doing something like a barrel
> > taper at "different" contours.
>
> I think it sounds like you are using a lathe. Sadly it seems that G5, 
> G5.1 and G5.2 only work in the G17 (XY) plane.
>
> http://linuxcnc.org/docs/2.7/html/gcode/g-code.html#gcode:g5

I see it (g17 only) mentioned for g5.1.  Since the g5.# stuff probably 
has a common code core, and it would be at least as handy on a lathe as 
on a mill, the adjective is indeed sad.  Since the huge majority of LCNC 
is orthogonal, would it do to file a bug?

In which case, in the armhf branch, there is another buglet that needs 
attention from the usability viewpoint. When in the MDI window, an up 
arrow will recall an older entry, but it can only be edited by carefully 
placing the cursor with the mouse, the arrow left-right keys are 
impotent.

It may be related to the fact that both the MDI line, and the line 
recalled in the history window are both highlighted, but the flashing 
cursor in the MDI's leftmost character position doesn't apparently 
indicate focus is actually in the MDI line.

Thanks Andy.

Cheers, Gene Heskett
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Re: [Emc-users] Encoder

[Gene Heskett]

On Tuesday 27 June 2017 14:56:25 dave wrote:

> Hi,
> The bad news is that my spare Koyo encoder is toast, why I don't know.
> Apparently happened a while
> ago and I didn't label it; sloppy on my part.
> Checked X axis with another encoder I swiped off the lathe and got
> reasonable counts.
> Now to order a couple of spares.
>
> However, I have this thru-shaft encoder I must have picked up surplus
> somewhere.

How big is the thru shaft? I might have a home for it. I about 7/8" of 
shaft out the rear of my x motor that I've not sawed off yet. 6.35mm 
shaft.

> Sumtek LHF-078-5000. Best I can tell it is 5000 ppr max freq of 250
> KHz. Voltage, pin out and
> output unknown except for being marked A, B, Z. Connector is a 3 x 3
> with 7 used.
> Apparently the output is a line driver.  Probably not worth fooling
> with but interesting.
>
> Dave
>
>
>
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Cheers, Gene Heskett
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Re: [Emc-users] Nurbs question

[andy pugh]

On 27 June 2017 at 18:59, Gene Heskett  wrote:

> I've not noted any great amount of mention of nurbs on the list, and I am
> wondering how usable it is in doing something like a barrel taper
> at "different" contours.
>

I think it sounds like you are using a lathe. Sadly it seems that G5,  G5.1
and G5.2 only work in the G17 (XY) plane.

http://linuxcnc.org/docs/2.7/html/gcode/g-code.html#gcode:g5

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[Emc-users] Encoder

[dave]

Hi,
The bad news is that my spare Koyo encoder is toast, why I don't know. 
Apparently happened a while

ago and I didn't label it; sloppy on my part.
Checked X axis with another encoder I swiped off the lathe and got 
reasonable counts.

Now to order a couple of spares.

However, I have this thru-shaft encoder I must have picked up surplus 
somewhere.
Sumtek LHF-078-5000. Best I can tell it is 5000 ppr max freq of 250 KHz. 
Voltage, pin out and
output unknown except for being marked A, B, Z. Connector is a 3 x 3  
with 7 used.
Apparently the output is a line driver.  Probably not worth fooling with 
but interesting.


Dave



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Re: [Emc-users] Nurbs question

[Gene Heskett]

On Tuesday 27 June 2017 13:59:48 Gene Heskett wrote:

> Greetings all;
>
> I've not noted any great amount of mention of nurbs on the list, and I
> am wondering how usable it is in doing something like a barrel taper
> at "different" contours.
>
> I am thinking in terms of a 6.5 Creedmoor, in 30" SS, which I can't
> get any slimmer than whats called a medium Palma contour, which will
> likely put old meat in the pot north of 15 lbs since its 13 and change
> with a 26" sporter weight barrel in it now.
>
> What I'd like to do is put the last 20" of it on a diet to see if I
> can get the weight, and balance back to what I've been used to since
> the middle '60's.
>
> What I have in mind is a 5 or 6 point curve that I can compose to look
> like what I want, but about 6" long, then scale it in the Z axis to
> fit the length by extending each anchor point by a scale factor
> multiplied by that points position on the short modeling plot. I am
> assuming that stretching the z with a fixed scale, will not distort
> the x shape to a noticeable degree?
>
> Secondarily, since facing it off against the side of a diamond wheel
> will destroy the factory satin finish, how is the best way to restore
> that when I've reached the size & weight goals?
>
> Thanks for any hints, particularly about shapes that will reduce the
> muzzle whipping on discharge since thats the vertical stringing on the
> target, given that its vertical, since bedding errors can throw it in
> any direction.
>
> Many thanks for answers from the experts here.
>
> Cheers, Gene Heskett

And I just had my first point rejected because it did not include a y 
point, so now I'm asking what if any command will make it work in xz 
mode?

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Nurbs question

[dave]

On 06/27/2017 10:59 AM, Gene Heskett wrote:

Greetings all;

I've not noted any great amount of mention of nurbs on the list, and I am
wondering how usable it is in doing something like a barrel taper
at "different" contours.

I am thinking in terms of a 6.5 Creedmoor, in 30" SS, which I can't get
any slimmer than whats called a medium Palma contour, which will likely
put old meat in the pot north of 15 lbs since its 13 and change with a
26" sporter weight barrel in it now.

What I'd like to do is put the last 20" of it on a diet to see if I can
get the weight, and balance back to what I've been used to since the
middle '60's.

What I have in mind is a 5 or 6 point curve that I can compose to look
like what I want, but about 6" long, then scale it in the Z axis to fit
the length by extending each anchor point by a scale factor multiplied
by that points position on the short modeling plot. I am assuming that
stretching the z with a fixed scale, will not distort the x shape to a
noticeable degree?

Secondarily, since facing it off against the side of a diamond wheel will
destroy the factory satin finish, how is the best way to restore that
when I've reached the size & weight goals?

Thanks for any hints, particularly about shapes that will reduce the
muzzle whipping on discharge since thats the vertical stringing on the
target, given that its vertical, since bedding errors can throw it in
any direction.

Many thanks for answers from the experts here.

Cheers, Gene Heskett

Gene,
Try fitting the curved part to a 2nd order polynomial. Stick some points 
out there, modify until the
the curve looks right, then fit. A small program can then output gcode 
as z vs x with whatever point

spacing you want.
Polish: cover the bed of your lathe with a oiled cloth to catch the grit 
and polish between centers until
you get the surface finish you want. Cleanup the last bit with the next 
finer grit by hand and parallel
to the bore.  I usually finish up with well worn 320 grit but you can 
polish to your hearts content.

You could even swamp it if you wanted to. ;-)

Hint: excel ...however I'm certain there is something already compiled 
that will do the job.


Dave


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Re: [Emc-users] Rough motion with servos

[Les Newell]

150 uS??  YIKES!  That is not generally good enough for even a servo 
system


I have done a lot of work with PID loops in various non LinuxCNC systems 
and in my general experience they generally seem to be very tolerant to 
timing variation. After all we are dealing with motors that have a 
bandwidth far lower than the PID loop speed. Anyway I have two boxes 
here so I can run back-to-back tests at some point.


I think I may have found the problem. Pncconf doesn't connect 
pid.n.feedback-deriv to the encoder velocity. The version of EMC I am 
running doesn't have feedback-deriv so my config doesn't either. With no 
connection, pid estimates the derivative and something funky is going on 
with that estimation. Sometimes the machine twitches while stationary 
which makes it a lot easier to see what is going on. Watching 
feedback-deriv on halscope I can see it move at exactly the same moment 
as the output jumps. A few milliseconds later the encoder velocity moves 
in response.


After connecting the encoder velocity to feedback-deriv my tuning values 
have to be very different but the twitching appears to have gone away. 
The tuning at the moment is very rough with just P,D and FF used. I need 
to experiment further and tune the axis properly before saying the 
problem is definitely fixed. Now I need to try to figure out why my 
jogwheels (one per axis) don't work.


Is there a reason why Pncconf doesn't connect the encoder velocity? By 
the way Pncconf wouldn't let me set the maximum feed rate to more than 
2000mm/min which is a bit annoying as the machine is capable of 4800.


Les




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[Emc-users] Nurbs question

[Gene Heskett]

Greetings all;

I've not noted any great amount of mention of nurbs on the list, and I am 
wondering how usable it is in doing something like a barrel taper 
at "different" contours.

I am thinking in terms of a 6.5 Creedmoor, in 30" SS, which I can't get 
any slimmer than whats called a medium Palma contour, which will likely 
put old meat in the pot north of 15 lbs since its 13 and change with a 
26" sporter weight barrel in it now.

What I'd like to do is put the last 20" of it on a diet to see if I can 
get the weight, and balance back to what I've been used to since the 
middle '60's.

What I have in mind is a 5 or 6 point curve that I can compose to look 
like what I want, but about 6" long, then scale it in the Z axis to fit 
the length by extending each anchor point by a scale factor multiplied 
by that points position on the short modeling plot. I am assuming that 
stretching the z with a fixed scale, will not distort the x shape to a  
noticeable degree?

Secondarily, since facing it off against the side of a diamond wheel will 
destroy the factory satin finish, how is the best way to restore that 
when I've reached the size & weight goals?

Thanks for any hints, particularly about shapes that will reduce the 
muzzle whipping on discharge since thats the vertical stringing on the 
target, given that its vertical, since bedding errors can throw it in 
any direction.

Many thanks for answers from the experts here.

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)
Genes Web page 

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Re: [Emc-users] Rough motion with servos

[Todd Zuercher]

What version of Linuxcnc (EMC2) were you running before the upgrade?
I think there were some changes in how PIDs were handled between v2.5 and 2.7 
that usually require a little servo returning.

- Original Message -
> From: "Les Newell" 
> To: emc-users@lists.sourceforge.net
> Sent: Tuesday, June 27, 2017 10:01:34 AM
> Subject: [Emc-users] Rough motion with servos
> 
> I have been running my lathe using EMC for many years and decided to
> upgrade to the latest LinuxCNC. The computer I am using is showing
> it's
> age and the ancient version of Debian I have been running won't even
> boot properly on my new computer.
> 
> The lathe has a 5i20 and a 7i29 to run the servos. Using the same PID
> settings as I had in EMC I get odd random spikes in the Z axis motor
> command signal, roughly about one to two a second. If I look at
> pid.z.output with halscope I can see the spikes. This is on the same
> computer and hardware as I was running EMC, which ran really
> smoothly. I
> changed the computer and the results are the same. I even used
> Pncconf
> to create an absolute minimum spec configuration and it does the same
> thing.
> 
> I tried both LinuxCNC 2.7.9 and Git head. Does anyone have any ideas
> why
> this would be happening?
> 
> Les
> 
> 
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Re: [Emc-users] Rough motion with servos

[Nicklas Karlsson]

Even though latency run well then I user computer for others at the same time I 
sometimes get a latency delay and are on the path to give up ordinary computer 
for servo threads. I think a small simpler computer will be more than enough 
and then I am free to move display.


On Tue, 27 Jun 2017 17:07:10 +0100
Les Newell  wrote:

> Hi Dave,
> 
> Just ran latency test on the old computer with LinuxCNC 32us servo 54us 
> base. I moved some windows, opened a few programs etc. As I mentioned 
> before I had checked on the new computer and although it wasn't great it 
> was good enough. The fact that the fault is identical on two very 
> different computers tends to rule out the computer.
> 
> Les
> 
> On 27/06/2017 16:43, Dave Caroline wrote:
> > "The computer I am using is showing it's age and the ancient version
> > of Debian I have been running won't even boot properly on my new
> > computer." implies some change to us, what?, changing OS will change
> > the latency too
> >
> >
> > Dave
> >
> > --
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> 
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Re: [Emc-users] Rough motion with servos

[Jon Elson]

On 06/27/2017 10:31 AM, Les Newell wrote:
Same PC, same hardware, same settings. The only difference 
between the two setups is the hard drive. Changing the PC 
(AMD processor VS Intel on the original) had no effect on 
the symptoms. I checked latency on the new PC and if I 
remember correctly worst case after a couple of hours was 
~150us. Not good for steppers but fine for servos.


150 uS??  YIKES!  That is not generally good enough for even 
a servo system, although Peter's PLL scheme probably makes 
it usable, but not very good.  With RTAI, I generally get 
about 10 - 15 us on any machine I think is good enough to 
use.  On linux-preempt, it is more like 15-20 us.  Note that 
150 us is 15% of the 1 KHz servo cycle.
I haven't had time to try tracing back from PID. That is 
probably my next job.


First thing to do is bring up the encoder velocity, and look 
for physically impossible velocity spikes.  If the encoder 
is being misread, or there are bad latency hiccups, you can 
see spikes in the velocity that can't be real, that's an 
immediate sign of some kind of difficulty between the 
encoder shaft and the CPU.  If you see them, then it can 
take some detective work to determine where they are coming 
from.  If no spikes, then you may just need to retune the 
PID.  There could have been subtle changes in the way PID 
works that make your old numbers less than optimum.


Jon

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Re: [Emc-users] Rough motion with servos

[Les Newell]

Hi Dave,

Just ran latency test on the old computer with LinuxCNC 32us servo 54us 
base. I moved some windows, opened a few programs etc. As I mentioned 
before I had checked on the new computer and although it wasn't great it 
was good enough. The fact that the fault is identical on two very 
different computers tends to rule out the computer.


Les

On 27/06/2017 16:43, Dave Caroline wrote:

"The computer I am using is showing it's age and the ancient version
of Debian I have been running won't even boot properly on my new
computer." implies some change to us, what?, changing OS will change
the latency too


Dave

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Re: [Emc-users] Rough motion with servos

[Dave Caroline]

"The computer I am using is showing it's age and the ancient version
of Debian I have been running won't even boot properly on my new
computer." implies some change to us, what?, changing OS will change
the latency too


Dave

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Re: [Emc-users] Rough motion with servos

[Les Newell]

Same PC, same hardware, same settings. The only difference between the 
two setups is the hard drive. Changing the PC (AMD processor VS Intel on 
the original) had no effect on the symptoms. I checked latency on the 
new PC and if I remember correctly worst case after a couple of hours 
was ~150us. Not good for steppers but fine for servos.


I haven't had time to try tracing back from PID. That is probably my 
next job.


Les

On 27/06/2017 16:15, Jon Elson wrote:

On 06/27/2017 09:01 AM, Les Newell wrote:
I have been running my lathe using EMC for many years and decided to 
upgrade to the latest LinuxCNC. The computer I am using is showing 
it's age and the ancient version of Debian I have been running won't 
even boot properly on my new computer.


The lathe has a 5i20 and a 7i29 to run the servos. Using the same PID 
settings as I had in EMC I get odd random spikes in the Z axis motor 
command signal, roughly about one to two a second. If I look at 
pid.z.output with halscope I can see the spikes. This is on the same 
computer and hardware as I was running EMC, which ran really 
smoothly. I changed the computer and the results are the same. I even 
used Pncconf to create an absolute minimum spec configuration and it 
does the same thing.


I tried both LinuxCNC 2.7.9 and Git head. Does anyone have any ideas 
why this would be happening?
Have you run the latency tests?  Are the numbers good?  Any time you 
change the hardware, OR kernel, you need to check that the RT 
performance is acceptable.


Jon

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Re: [Emc-users] Rough motion with servos

[Jon Elson]

On 06/27/2017 09:01 AM, Les Newell wrote:
I have been running my lathe using EMC for many years and 
decided to upgrade to the latest LinuxCNC. The computer I 
am using is showing it's age and the ancient version of 
Debian I have been running won't even boot properly on my 
new computer.


The lathe has a 5i20 and a 7i29 to run the servos. Using 
the same PID settings as I had in EMC I get odd random 
spikes in the Z axis motor command signal, roughly about 
one to two a second. If I look at pid.z.output with 
halscope I can see the spikes. This is on the same 
computer and hardware as I was running EMC, which ran 
really smoothly. I changed the computer and the results 
are the same. I even used Pncconf to create an absolute 
minimum spec configuration and it does the same thing.


I tried both LinuxCNC 2.7.9 and Git head. Does anyone have 
any ideas why this would be happening?
Have you run the latency tests?  Are the numbers good?  Any 
time you change the hardware, OR kernel, you need to check 
that the RT performance is acceptable.


Jon

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Re: [Emc-users] Rough motion with servos

[Dave Caroline]

New PC new possible latency problems?

Dave Caroline

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Re: [Emc-users] Rough motion with servos

[Peter C. Wallace]

On Tue, 27 Jun 2017, Les Newell wrote:


Date: Tue, 27 Jun 2017 15:01:34 +0100
From: Les Newell 
Reply-To: "Enhanced Machine Controller (EMC)"

To: emc-users@lists.sourceforge.net
Subject: [Emc-users] Rough motion with servos

I have been running my lathe using EMC for many years and decided to upgrade 
to the latest LinuxCNC. The computer I am using is showing it's age and the 
ancient version of Debian I have been running won't even boot properly on my 
new computer.


The lathe has a 5i20 and a 7i29 to run the servos. Using the same PID 
settings as I had in EMC I get odd random spikes in the Z axis motor command 
signal, roughly about one to two a second. If I look at pid.z.output with 
halscope I can see the spikes. This is on the same computer and hardware as I 
was running EMC, which ran really smoothly. I changed the computer and the 
results are the same. I even used Pncconf to create an absolute minimum spec 
configuration and it does the same thing.


I tried both LinuxCNC 2.7.9 and Git head. Does anyone have any ideas why this 
would be happening?


Les



Can you trace the PID output spike back to its source?

Maybe there's a encoder noise issue or something similar
(that may have changed signtly with a new PC due to grounding differences etc)




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Peter Wallace
Mesa Electronics

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[Emc-users] Rough motion with servos

[Les Newell]

I have been running my lathe using EMC for many years and decided to 
upgrade to the latest LinuxCNC. The computer I am using is showing it's 
age and the ancient version of Debian I have been running won't even 
boot properly on my new computer.


The lathe has a 5i20 and a 7i29 to run the servos. Using the same PID 
settings as I had in EMC I get odd random spikes in the Z axis motor 
command signal, roughly about one to two a second. If I look at 
pid.z.output with halscope I can see the spikes. This is on the same 
computer and hardware as I was running EMC, which ran really smoothly. I 
changed the computer and the results are the same. I even used Pncconf 
to create an absolute minimum spec configuration and it does the same thing.


I tried both LinuxCNC 2.7.9 and Git head. Does anyone have any ideas why 
this would be happening?


Les


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Re: [Emc-users] steppers with encoders in closed loop

[Todd Zuercher]

- Original Message -
> From: "Valerio Bellizzomi" 
> To: "Enhanced Machine Controller (EMC)" 
> Sent: Tuesday, June 27, 2017 3:58:34 AM
> Subject: Re: [Emc-users] steppers with encoders in closed loop
> 
> I have the P parameter set to 1000 and the motors are quiet.
> Previously
> pncconf had set P to 1 and the motors made noise like hell and
> vibrated.

P = 1000 Will usually only work for an open loop stepper setup using the sudo 
feedback from the hardware stepgen.

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Re: [Emc-users] steppers with encoders in closed loop

[Valerio Bellizzomi]

On Mon, 2017-06-26 at 16:27 -0400, tom-...@bgp.nu wrote:
> Thanks Todd, your suggestion lead me to the issue.  Turns out PNConfig sets 
> the P term to 1000 (and Deadband to 0.0) at which point I got a terrible nose 
> from the motors.  Setting the P term down to 10, and setting Deadband to 
> 0.0005 has it running quite smoothly.  Now to run Halscope and get the tuning 
> right…
> 
> -Tom


I have the P parameter set to 1000 and the motors are quiet. Previously
pncconf had set P to 1 and the motors made noise like hell and
vibrated.



>  
> 
> > On Jun 26, 2017, at 10:28 AM, Todd Zuercher  wrote:
> > 
> > Maybe you've already tried this, but I would think the easiest way is to 
> > use PNCcofig to create an ordinary stepper configuration.  It will set up a 
> > velocity mode config with the hardware stepgen sending the feedback to 
> > close the pid loop.  Get that working.  Then modify that config by adding 
> > the encoder reading, and replace the stepgen's feed back with the encoder's 
> > feedback to the pid loop and to the axis.N.pos-fb (or joint.N.pos-fb in 
> > Master)  Then adjust the P tuning till it "works".  I have such a setup on 
> > a machine using step/dir servos, and using it with step motors would be 
> > exactly the same (except for the PID tuning.)
> > 
> > The trick is to only try making one major modification at a time.  So first 
> > get a velocity mode stepgen config working (without encoder feedback), Then 
> > add encoder feedback (do it one axis at a time.) First get the DRO's 
> > working with the encoder feedback.  Then connect the encoders to the PID 
> > loops.
> > 
> > - Original Message -
> > From: "Tom Easterday" 
> > To: "Enhanced Machine Controller (EMC)" 
> > Sent: Monday, June 26, 2017 8:37:47 AM
> > Subject: Re: [Emc-users] steppers with encoders in closed loop
> > 
> > Exactly, and any help in getting my stall detection and position tracking 
> > working using velocity mode would be greatly appreciated 
> > 
> > -Tom
> > 
> >> On Jun 26, 2017, at 6:52 AM, Rene Hopf  wrote:
> >> 
> >> there is no benefit in using them in linuxcnc, apart from stall detection 
> >> or position tracking.
> >> 
> > 
> > 
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