Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing - Question about using a rotary table

[Ian W. Wright]

One thing which does need addressing is that, whatever 
solution is found ( and I suspect that we may actually be 
approaching a consensus on what is required...). the rotary 
axis/axes need to be able to home either to the position in 
which they currently are or to the nearest '0' when EMC2 is 
first switched on. It will be no use having a system where, 
if the last job you did was milling a 12" length of 40 
thread, hitting the home button will cause the rotary to set 
off on an interminable unwind.. Some while ago I got used to 
running a short script of G54, G92.1, G10 etc. to reset the 
home position of the axes as they were starting in 'random' 
positions but the later versions of EMC have sorted that 
problem and homing is now easy. However, as EMC will not now 
allow any operation without all the axes being homed first, 
optionally running such as 'position setting' script before 
a rotary sets off on a long unwind is not now possible.

Ian
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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing - Question about using a rotary table

[Steve Blackmore]

On Sat, 03 Oct 2009 08:54:25 +0100, you wrote:

> However, as EMC will not now 
>allow any operation without all the axes being homed first, 
>optionally running such as 'position setting' script before 
>a rotary sets off on a long unwind is not now possible.
>
Hi Ian, put

NO_FORCE_HOMING=1

in the [TRAJ] section of your ini file, that cancels out the nanny state
homing, you can still home after if you wish .

Steve Blackmore
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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing

[Steve Blackmore]

On Fri, 2 Oct 2009 22:32:02 +0100, you wrote:

>2009/10/2 Chris Radek :
>
>>> Also as Andy pointed out, you can do an optional short move to zero in
>>> some controllers, invent a code for it if considered essential.
>>
>> OK, I agree a counterproposal might have this scheme.
>
>G1.1 and G0.1 ? Take the shortest route and reset the machine
>coordinates to match the relative ones. (I am not sure about that last
>bit, but I think it makes sense)

I agree there should be another code, perhaps not G0.1 or G1.1

Something like G28.2 or G30.2 would be nearer to the function.

It definitely shouldn't reset the co-ords unless specifically told to do
so using G91.1 or G92.2

Steve Blackmore
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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing - Question about using a rotary table

[John Thornton]

You can disable that feature if you wish.

http://www.linuxcnc.org/docview/html//config_ini_config.html#sub:[TRAJ]-section

John

On 3 Oct 2009 at 8:54, Ian W. Wright wrote:

> problem and homing is now easy. However, as EMC will not now 
> allow any operation without all the axes being homed first, 
> optionally running such as 'position setting' script before 
> a rotary sets off on a long unwind is not now possible.
> 
> Ian
> ___
> Ian W. Wright
> Sheffield  UK


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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing - Question about using a rotary table

[Andy Pugh]

2009/10/3 Ian W. Wright :
> It will be no use having a system where,
> if the last job you did was milling a 12" length of 40
> thread, hitting the home button will cause the rotary to set
> off on an interminable unwind..

A rotary axis will only ever home to the home switch, and it is hard
to think of a way that could ever be more than 360 degrees away. I
think that if it was at 40 turns + 10 degrees it would unwind 10
degrees, see the switch, and zero-out the 40 full turns in the machine
coordinates.

How many rotary axes actually have home switches anyway?

I am embarassed to say that I have never noticed if EMC holds relative
position information during a power-down, or machine position for that
matter.

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[Emc-users] Advice for mesa 5i20 servo drivers needed

[Rob Jansen]

I got triggered by the mail from Klemen about his servo amplifiers.

I own a 5i20 card, currently it is controlling my EMC mill using stepper 
motors.
A conversion towards servo motors is on its way - the servos have been 
ordered (both 1.7 and 2.5 Nm versions to play with).

The question now is what kind of servo drivers to use?
I am looking at the 7i40 or 7i27 cards from Mesa electronics but the 
7i27 is too small for the larger motor (60V motor where the 7i27 only 
goes up to 40V).
I did not look at the 7i33 that Klemen used - this could also be an option.
What is the way to go? PWM controlled servo drivers or analogue, go for 
the 7i40 or use the 7i33 (0-10V interface) with analogue servo 
amplifiers (and what kind of) ?
The motors are brush type servo motors, the small motors are 48V 3.5A 
and the larger one is 60V 4.5A but these are nominal currents.

My current best guess is that the 7i40 is a good card for the job and 
with 2 channels per card (of 149 USD) not expensive. Another card is the 
card from Pico Systems and with 20A it can deliver a higher current but 
this comes with a price (125 USD per channel). But ... the 7i40 HV 
version only goes up to 7A and the smaller motor specifies a max. 
current of 24A.
So the big question is if the 7i40 is enough or should I spend more 
money on the Pico Systems PWM Servo amps or should I even go for another 
solution?
Unfortunately the motors are still in the mail - as soon as these arrive 
I'll be testing them to see what the real power requirements are.

Any input is greatly appreciated.

Regards,

Rob


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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing - Question about using a rotary table

[robert]

>
> I am embarassed to say that I have never noticed if EMC holds relative
> position information during a power-down, or machine position for that
> matter.
>   
Only when you use the position_file option
POSITION_FILE = position.txt If set to a non-empty value, the joint 
positions are stored between
runs in this file. This allows the machine to start with the same 
coordinates it had on shutdown.
This assumes there was no movement of the machine while powered off. If 
unset, joint
positions are not stored and will begin at 0 each time EMC is started. 
This can help on smaller
machines without home switches

but this should not be used as a switch on and go option as EMC still 
has no way of knowing where u are from swithc off to switch on, unless 
your reading absolute encoders etc but then u would't need the 
position_file ;)

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Re: [Emc-users] WG: Re: WG: Re: axis and batch processing

[Jan Van Gilsen]

Chris,

I've managed to get a preview that seemed to display a combination of
the files.

Set the "PROGRAM_PREFIX" setting in the  ini file to the location of
the called files
Removed the M30 codes from the end of each sub.

regards, Jan



On Thu, Oct 1, 2009 at 12:54, Chris Epicier  wrote:
> Hi all
>
> I am in the process of cutting parts, due out soon. Should be doing million 
> things, other than keepin my cnc busy.
>
> I checked and rechecked the syntax in bot, master, labels and other files. I 
> cannot find a mistake there.
>
> Is there a way I can debug this? A way to set axis/emc to talk to me about 
> what is going wrong?
>
> Greets
>
> chris
>
> Besides: had yesterday a couple of guys couriuos abut the cnc cutting. one of 
> them works for steel cutter. He said he was impressed about the features and 
> easiness emc and axis can be handled. Also my finding: great! So a big 
> faaa thankyou to all that made emc what it is now!
>
>
>> Jan
>>
>> Thank you very much for the quick reply. Stephen had
>> pointed me to this also, I have amended the files
>> accordingly and still get "Bad Number Format".
>>
>> I attach the original files not stripped. Maybe there is
>> something there that shoudl not be. Besides, all files
>> rune
>> smoothly as truely standa alone files. So I do not believe
>> it is actually within the sub files.
>>
>> greets chris
>>
>> > > Betreff: Re: [Emc-users] WG: Re: axis and batch
>> > processing
>> > > An: "Enhanced Machine Controller (EMC)" 
>> > > Datum: Mittwoch, 30. September 2009, 19:48
>> > > Chris,
>> > >
>> > > in file labels.ngc, line 1: Olabels sub
>> > > Should be: O sub
>> > > and: Olabels endsub
>> > > Should be O endsub
>> > >
>> > > This syntax error should also be corrected in
>> the
>> > other
>> > > files.
>> > >
>> > > regards, Jan
>> > >
>> > > On Wed, Sep 30, 2009 at 18:00, Chris Epicier
>> 
>> > > wrote:
>> > > >
>> > > >
>> > > >
>> > > > Dear Stephen
>> > > >
>> > > >> >>Check this chapter in the
>> manual:
>> > > >> >>http://linuxcnc.org/docs/2.3/html/gcode_main.html#r3_7
>> > > >> >>Regards, Jan
>> > > >
>> > > > I did, but I just cannot get it to work. I
>> have
>> > 5
>> > > files:
>> > > >
>> > > > [master.ngc]
>> > > > O call
>> > > > O call
>> > > > O call
>> > > > O call
>> > > > G53 G0 X0Y0Z0
>> > > > [end of master.ngc]
>> > > >
>> > > >
>> > > > [labels.ngc]
>> > > > Olabels sub
>> > > > N0G20M6T2
>> > > > 
>> > > > N868M09
>> > > > N869M30
>> > > > Olabels endsub
>> > > > M2
>> > > > [end of labels.ngc]
>> > > >
>> > > > [internal_contours.ngc]
>> > > > Ointernal_contours sub
>> > > > N0G20M6T2
>> > > > 
>> > > > N868M09
>> > > > N869M30
>> > > > Ointernal_contours endsub
>> > > > M2
>> > > > [end of internal_contours.ngc]
>> > > >
>> > > > [external_contours_rough.ngc]
>> > > > Oexternal_contours_rough sub
>> > > > N0G20M6T2
>> > > > 
>> > > > N868M09
>> > > > N869M30
>> > > > Oexternal_contours_rough endsub
>> > > > M2
>> > > > [end of external_contours_rough.ngc]
>> > > >
>> > > > [external_contours_finish.ngc]
>> > > > Oexternal_contours_finish sub
>> > > > N0G20M6T2
>> > > > 
>> > > > N868M09
>> > > > N869M30
>> > > > Oexternal_contours_finish endsub
>> > > > M2
>> > > > [end of external_contours_finish.ngc]
>> > > >
>> > > >
>> > > > All files are in the same directory. I
>> believe I
>> > got
>> > > the
>> > > > master file about right. What I doubt there
>> is if
>> > the
>> > > homing
>> > > > sequence is correct but that's not a
>> > showstopper.
>> > > >
>> > > > In  [labels.ngc] and all the other sub
>> files, I
>> > > doubt
>> > > > the missing line numbering. My programming
>> > experience
>> > > tells
>> > > > me, either it has to be ther or totally
>> omitted.
>> > > >
>> > > > If I load master ngc in axis, I get no
>> > errormessage.
>> > > when I
>> > > > run the file I get "Bad Number Format".
>> > > >
>> > > > I am lost now. What's wrong and where, any
>> help
>> > is
>> > > greatly
>> > > > appreciated.
>> > > >
>> > > > greets
>> > > >
>> > > > chris
>> > > >>
>> > > >>
>> > > >>
>> > > >>
>> > > >>
>> > > >> > >>
>> > > >> > >>
>> > > >> > >
>> > > >> >
>> > > >>
>> > >
>> >
>> >===
>> > > >> > >3.7 Calling Files
>> > > >> > >
>> > > >> > >To call a file name the file
>> the
>> > same as
>> > > your call
>> > > >> and
>> > > >> > include a sub and endsub. The file
>> must
>> > be in
>> > > the
>> > > >> directory
>> > > >> > pointed to by PROGRAM_PREFIX
>> > > >> > >
>> > > >> > >o call (a
>> named
>> > > file)
>> > > >> > >
>> > > >> > >or
>> > > >> > >
>> > > >> > >o123 call (a number
>> file)
>> > > >> > >
>> > > >> > >In the called file include the
>> oxxx
>> > sub
>> > > and endsub
>> > > >> and
>> > > >> > the file must be a valid file
>> > > >> > >
>> > > >> > >myfile.ngc
>> > > >> > >o sub
>> > > >> > >...
>> > > >> > >o endsub
>> > > >> > >M2
>> > > >> >
>> > >
>> >

[Emc-users] Parameter list

[VMAXEmbarq]

Thanks I was hoping there were more to work with other than the few simple 
fixture values listed.

I was hoping EMC was more fanuc like in nature where you can access most of 
the internal system parameters through macroB programing.

Thanks (;-) TP 



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Re: [Emc-users] Parameter list

[Andy Pugh]

2009/10/3 VMAXEmbarq :

> I was hoping EMC was more fanuc like in nature where you can access most of
> the internal system parameters through macroB programing.

It would be nice wouldn't it? Of course in an open project like this,
all things are possible.

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Re: [Emc-users] Encoders

[cogoman]

Note also, that if the pullup that's already there is very weak, the rise 
time would be slowed down, but the fall time would be fast. This could 
produce what we see in the encoder-a trace.  The 1k pullups might bring 
that trace closer to 50% duty cycle.

>> .  I would think a 1 K Ohm
>> resistor from +5 V to the A and B would make a big difference.  You can 
>> get +5 V from the game port or a
>> hard drive plug.  Yup, also looking closer, I see COORDINATED spikes in 
>> both A and B on a number of
>> cycles.  That reinforces my suspicion of the above.
>> 

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[Emc-users] PWM tuning with hostmot2 and 7i33

[Eric H. Johnson]

Hi all.

I did not want to hijack the "Advice for mesa 5i20 servo drivers needed"
thread, but this thread may cover some of the same issues. I am having two
issues, the first I think is minor, the second I am not so sure. 

1> When I try to run Setting | Calibration from tkemc, or the equivalent
under axis I get an error of the form:

af: 0 .main.top.fpage0
(followed by 4 lines starting with the same text)

Error in startup script: Invalid argument
  While executing
"hal getp {hm2_[HOSTMOT2](BOARD).0.encoder.00.scale}"
  ("eval" body line 1)
  evoked from within
"eval hal $args"
etc. 

If it matters, I am still running 2.3.0 as I am using the smp packages, and
have not updated them to the subsequent minor releases.

2> Tuning the servo motors

I am using the 7i43 Anything I/O card with the 7i33 quad analog servo
interface.

I am having a devil of a time getting anything close to smooth motion from
the motors in the PID tuning. I start, as I usually do by bringing up P, but
I start to get oscillations with a P value of about 20. If I use this value
to have it move to a position, it will over or undershoot the position by
1/2" (2500 encoder counts or 6/10ths of a turn of the motor shaft). The
motor is not coupled to the load at this point. Increasing P to about 160
stiffens it up to the point where one would think it would get within an
encoder count or two of the demanded position, however there is still a
strong oscillation of about +/- 0.1" (500 encoder counts or roughly 1/10th
turn of the motor shaft).

I then try bringing up I and D, but it is generally making little difference
until the values are large enough that it makes it worse. The basic problem
is that it is so bad I am having trouble even establishing a starting point
from which it will get better or worse. This is a retrofit of a system which
previously used a Galil 1800 series motion controller, and where tuning with
that system was no big deal. Galil does have a rather nice piece of tuning
software, but I don't recall even needing that.

Additionally, about six months ago I replaced an EMC system using the VTI
board (plus a 5i20 which only drove the laser) to use exclusively the 5i20
and 7i33 with the hostmot2 drivers. With the VTI card, tuning was a snap
because it ran smoothly for a large range of PID values. When I switched it
over to the 5i20, I again had a devil of a time getting it tuned, but
finally got something reasonably acceptable, but never as good as when using
the VTI board. It will still occasionally hum at idle for example, which
never happened under the previous configuration.

At the time, I thought it might be due to the PWM frequency, which I had to
set to 25Khz, as that was the maximum frequency acceptable to the laser.
With this configuration, there is no laser, so I have pwm_frequency set to
193Khz and pdm_frequency set to 6Mhz.

I keep thinking it is some value other than the PID values which is throwing
me, but so far I do not see it. I have included the relevant sections of the
ini and hal files for the axis I am trying to tune below.

->ini file<-
[AXIS_1]

TYPE =LINEAR
HOME =0.000
MAX_VELOCITY =   10.0
MAX_ACCELERATION =   40.0
BACKLASH =   0.000
INPUT_SCALE =-
OUTPUT_SCALE =1.000
OUTPUT_OFFSET =  0.0
MIN_LIMIT =  0.0
MAX_LIMIT =180.0
FERROR =100.0
MIN_FERROR = 0.4
HOME_OFFSET =0.10
HOME_SEARCH_VEL = 0.10
HOME_LATCH_VEL =   -0.01
HOME_USE_INDEX =  NO
HOME_IGNORE_LIMITS =YES
MAX_OUTPUT =   1.0
# PID tuning params
DEADBAND =  0.15
P =   150.00
I =   0.0
D =   0.00
FF0 = 0.000
FF1 = 1.000
FF2 =   0.0
BIAS =   0.000
->ini file<-

->hal file<-
# standard components
loadrt pid num_chan=3

addf pid.0.do-pid-calcsservo-thread
addf pid.1.do-pid-calcsservo-thread
addf pid.2.do-pid-calcsservo-thread

setp hm2_7i43.0.pwmgen.pwm_frequency   193000
setp hm2_7i43.0.pwmgen.pdm_frequency   600


# 
# Y [1] Axis
# 

# axis enable chain
newsig emcmot.01.enable bit
sets emcmot.01.enable FALSE
net emcmot.01.enable => pid.1.enable
net 

Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Chris Radek]

On Sat, Oct 03, 2009 at 11:11:35AM -0400, Eric H. Johnson wrote:
> 
> 1> When I try to run Setting | Calibration from tkemc, or the equivalent
> under axis I get an error of the form:

...

> If it matters, I am still running 2.3.0 as I am using the smp packages, and
> have not updated them to the subsequent minor releases.

You can always see the bugs fixed in new releases on the wiki page

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

This is the first link on the front page of the wiki.  In this case
you will see 

"calibration now works with hostmot2-style hal files"

fixed in EMC 2.3.2.


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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Peter C. Wallace]

On Sat, 3 Oct 2009, Eric H. Johnson wrote:

> Date: Sat, 3 Oct 2009 11:11:35 -0400
> From: Eric H. Johnson 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: "'Enhanced Machine Controller (EMC)'" 
> Subject: [Emc-users] PWM tuning with hostmot2 and 7i33
> 
> 2> Tuning the servo motors
>
> I am using the 7i43 Anything I/O card with the 7i33 quad analog servo
> interface.
>
> I am having a devil of a time getting anything close to smooth motion from
> the motors in the PID tuning. I start, as I usually do by bringing up P, but
> I start to get oscillations with a P value of about 20. If I use this value
> to have it move to a position, it will over or undershoot the position by
> 1/2" (2500 encoder counts or 6/10ths of a turn of the motor shaft). The
> motor is not coupled to the load at this point. Increasing P to about 160
> stiffens it up to the point where one would think it would get within an
> encoder count or two of the demanded position, however there is still a
> strong oscillation of about +/- 0.1" (500 encoder counts or roughly 1/10th
> turn of the motor shaft).
>
> I then try bringing up I and D, but it is generally making little difference
> until the values are large enough that it makes it worse. The basic problem
> is that it is so bad I am having trouble even establishing a starting point
> from which it will get better or worse. This is a retrofit of a system which
> previously used a Galil 1800 series motion controller, and where tuning with
> that system was no big deal. Galil does have a rather nice piece of tuning
> software, but I don't recall even needing that.

My opinion is that you should _NEVER_ use _ANY_ I until you are within a gnats 
eyelash of perfect tuning. It really just gets in the way.

I would make a test fixture so you can take a step motion, increase P until it 
overshoots in response to the step, add D until theres no or very little 
overshoot and repeat (increasing P and D) until you get good response to the 
step input.

Then I would make another test with a long cruise, and adjust FF1 for minimum 
error.

Only at this point would I start adding some I

>
> Additionally, about six months ago I replaced an EMC system using the VTI
> board (plus a 5i20 which only drove the laser) to use exclusively the 5i20
> and 7i33 with the hostmot2 drivers. With the VTI card, tuning was a snap
> because it ran smoothly for a large range of PID values. When I switched it
> over to the 5i20, I again had a devil of a time getting it tuned, but
> finally got something reasonably acceptable, but never as good as when using
> the VTI board. It will still occasionally hum at idle for example, which
> never happened under the previous configuration.
>
> At the time, I thought it might be due to the PWM frequency, which I had to
> set to 25Khz, as that was the maximum frequency acceptable to the laser.
> With this configuration, there is no laser, so I have pwm_frequency set to
> 193Khz and pdm_frequency set to 6Mhz.

PDM at 6 MHz is correct, but is it selected (PWM is default)

>
> I keep thinking it is some value other than the PID values which is throwing
> me, but so far I do not see it. I have included the relevant sections of the
> ini and hal files for the axis I am trying to tune below.
>
> ->ini file<-
> [AXIS_1]
>
> TYPE =LINEAR
> HOME =0.000
> MAX_VELOCITY =   10.0
> MAX_ACCELERATION =   40.0
> BACKLASH =   0.000
> INPUT_SCALE =-
> OUTPUT_SCALE =1.000
> OUTPUT_OFFSET =  0.0
> MIN_LIMIT =  0.0
> MAX_LIMIT =180.0
> FERROR =100.0
> MIN_FERROR = 0.4
> HOME_OFFSET =0.10
> HOME_SEARCH_VEL = 0.10
> HOME_LATCH_VEL =   -0.01
> HOME_USE_INDEX =  NO
> HOME_IGNORE_LIMITS =YES
> MAX_OUTPUT =   1.0
> # PID tuning params
> DEADBAND =  0.15
> P =   150.00
> I =   0.0
> D =   0.00
> FF0 = 0.000
> FF1 = 1.000
> FF2 = 0.0
> BIAS =   0.000
> ->ini file<-
>
> ->hal file<-
> # standard components
> loadrt pid num_chan=3
>
> addf pid.0.do-pid-calcsservo-thread
> addf pid.1.do-pid-calcsservo-thread
> addf pid.2.do-pid-calcsservo-thre

Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[John Thornton]

Peter,

Could you describe a bit more the test fixture you mention and the step motion. 
I'm not clear 
on this and would like to understand a bit better how to tune a servo as well.

Thanks
John

On 3 Oct 2009 at 10:02, Peter C. Wallace wrote:

> My opinion is that you should _NEVER_ use _ANY_ I until you are
> within a gnats 
> eyelash of perfect tuning. It really just gets in the way.
> 
> I would make a test fixture so you can take a step motion, increase
> P until it 
> overshoots in response to the step, add D until theres no or very
> little 
> overshoot and repeat (increasing P and D) until you get good
> response to the 
> step input.
> 
> Then I would make another test with a long cruise, and adjust FF1
> for minimum 
> error.
> 
> Only at this point would I start adding some I



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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Peter C. Wallace]

On Sat, 3 Oct 2009, John Thornton wrote:

> Date: Sat, 03 Oct 2009 12:28:19 -0600
> From: John Thornton 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: Enhanced Machine Controller EEMC" 
> Subject: Re: [Emc-users] PWM tuning with hostmot2 and 7i33
> 
> Peter,
>
> Could you describe a bit more the test fixture you mention and the step 
> motion. I'm not clear
> on this and would like to understand a bit better how to tune a servo as well.
>
> Thanks
> John


Either a gcode or HAL test setup that can take a step (instant jump in 
commanded position) so the step response of the servo can be captured via 
HALScope. I cant really imagine hand tuning without being able to see a plot 
of the servo systems step response.

Peter Wallace
Mesa Electronics

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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Eric H. Johnson]

Peter,


>> My opinion is that you should _NEVER_ use _ANY_ I until you are within a
gnats eyelash of perfect tuning. It really just gets in the way.

I would make a test fixture so you can take a step motion, increase P until
it overshoots in response to the step, add D until theres no or very little
overshoot and repeat (increasing P and D) until you get good response to the
step input.

Then I would make another test with a long cruise, and adjust FF1 for
minimum error.

Only at this point would I start adding some I <<

I agree with you, and that was where I started. I then read this:
http://www.linuxcnc.org/docview/html//motion_pid_theory.html

Near the bottom:
"If the system must remain online, one tuning method is to first set the I
and D values to zero. Increase the P until the output of the loop
oscillates. Then increase I until oscillation stops. Finally, increase D
until the loop is acceptably quick to reach its reference. A fast PID loop
tuning usually overshoots slightly to reach the setpoint more quickly;
however, some systems cannot accept overshoot."

Regardless, the oscillation is so bad that I cannot get a starting point for
bringing in either D or I. Which is why I am suspecting I screwed up another
parameter separate from PID. I just don't see it off hand.

>> PDM at 6 MHz is correct, but is it selected (PWM is default)<<

I am using both the 7i43 and 7i33, so the use of pwm or pdm is entirely
internal to the Mesa products. The amplifier only cares about the resultant
analog output. Which works best with the 7I33, pwm mode or pdm mode? What
are the optimal settings?

Thanks,
Eric



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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Eric H. Johnson]

Chris,

Thanks, I should know by now to check that.

If I get a chance, I will do another smp build this weekend to get
everything caught up.

Regards,
Eric


You can always see the bugs fixed in new releases on the wiki page

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

This is the first link on the front page of the wiki.  In this case you will
see 

"calibration now works with hostmot2-style hal files"

fixed in EMC 2.3.2.



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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[John Thornton]

Ok, I think I understand now. So somethin to imput a change in the commanded 
position 
with a trigger for the scope and watch the commanded vs the actual position to 
tune that 
drive. How big of a step would you take?

Thanks
John

On 3 Oct 2009 at 10:35, Peter C. Wallace wrote:

> 
> Either a gcode or HAL test setup that can take a step (instant jump
> in 
> commanded position) so the step response of the servo can be
> captured via 
> HALScope. I cant really imagine hand tuning without being able to
> see a plot 
> of the servo systems step response.
> 
> Peter Wallace
> Mesa Electronics
> 


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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Peter C. Wallace]

On Sat, 3 Oct 2009, Eric H. Johnson wrote:

> Date: Sat, 3 Oct 2009 15:18:26 -0400
> From: Eric H. Johnson 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: "'Enhanced Machine Controller (EMC)'" 
> Subject: Re: [Emc-users] PWM tuning with hostmot2 and 7i33
> 
> Peter,
>
>
>>> My opinion is that you should _NEVER_ use _ANY_ I until you are within a
> gnats eyelash of perfect tuning. It really just gets in the way.
>
> I would make a test fixture so you can take a step motion, increase P until
> it overshoots in response to the step, add D until theres no or very little
> overshoot and repeat (increasing P and D) until you get good response to the
> step input.
>
> Then I would make another test with a long cruise, and adjust FF1 for
> minimum error.
>
> Only at this point would I start adding some I <<
>
> I agree with you, and that was where I started. I then read this:
> http://www.linuxcnc.org/docview/html//motion_pid_theory.html
>
> Near the bottom:
> "If the system must remain online, one tuning method is to first set the I
> and D values to zero. Increase the P until the output of the loop
> oscillates. Then increase I until oscillation stops. Finally, increase D
> until the loop is acceptably quick to reach its reference. A fast PID loop
> tuning usually overshoots slightly to reach the setpoint more quickly;
> however, some systems cannot accept overshoot."
>
> Regardless, the oscillation is so bad that I cannot get a starting point for
> bringing in either D or I. Which is why I am suspecting I screwed up another
> parameter separate from PID. I just don't see it off hand.
>
>>> PDM at 6 MHz is correct, but is it selected (PWM is default)<<
>
> I am using both the 7i43 and 7i33, so the use of pwm or pdm is entirely
> internal to the Mesa products. The amplifier only cares about the resultant
> analog output. Which works best with the 7I33, pwm mode or pdm mode? What
> are the optimal settings?

PDM 6MHz, PWM/PDM selection is a HostMot2 setup option


>
> Thanks,
> Eric
>
>
>
> --
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>

Peter Wallace
Mesa Electronics

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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Peter C. Wallace]

On Sat, 3 Oct 2009, Eric H. Johnson wrote:

> Date: Sat, 3 Oct 2009 15:18:26 -0400
> From: Eric H. Johnson 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: "'Enhanced Machine Controller (EMC)'" 
> Subject: Re: [Emc-users] PWM tuning with hostmot2 and 7i33
> 
> Peter,
>
>
>>> My opinion is that you should _NEVER_ use _ANY_ I until you are within a
> gnats eyelash of perfect tuning. It really just gets in the way.
>
> I would make a test fixture so you can take a step motion, increase P until
> it overshoots in response to the step, add D until theres no or very little
> overshoot and repeat (increasing P and D) until you get good response to the
> step input.
>
> Then I would make another test with a long cruise, and adjust FF1 for
> minimum error.
>
> Only at this point would I start adding some I <<
>
> I agree with you, and that was where I started. I then read this:
> http://www.linuxcnc.org/docview/html//motion_pid_theory.html
>
> Near the bottom:
> "If the system must remain online, one tuning method is to first set the I
> and D values to zero. Increase the P until the output of the loop
> oscillates. Then increase I until oscillation stops. Finally, increase D
> until the loop is acceptably quick to reach its reference. A fast PID loop
> tuning usually overshoots slightly to reach the setpoint more quickly;
> however, some systems cannot accept overshoot."
>
> Regardless, the oscillation is so bad that I cannot get a starting point for
> bringing in either D or I. Which is why I am suspecting I screwed up another
> parameter separate from PID. I just don't see it off hand.

Heres what I would check:

Can you get a HALScope plot of the step response?

Do you have velocity or torque mode amplifiers?

(Torque mode amplifiers will typically require a higher sample rate and are 
tougher to tune)
your .6" error even with a P of 20 suggests torque mode to me

What number of counts generates a full scale drive (+- 10V) with your current 
P setting? (Disconnect analog out from amps and measure voltage versus error 
counts)


>
>>> PDM at 6 MHz is correct, but is it selected (PWM is default)<<
>
> I am using both the 7i43 and 7i33, so the use of pwm or pdm is entirely
> internal to the Mesa products. The amplifier only cares about the resultant
> analog output. Which works best with the 7I33, pwm mode or pdm mode? What
> are the optimal settings?
>
> Thanks,
> Eric
>
>
>
> --
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> is the only developer event you need to attend this year. Jumpstart your
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> ahead of the curve. Join us from November 9-12, 2009. Register now!
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>

Peter Wallace
Mesa Electronics

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Re: [Emc-users] Encoders

[Steve Blackmore]

On Fri, 02 Oct 2009 15:24:24 -0400, you wrote:

>Page 5 and 6 show it but not at a good time scale, page 7 from the base 
>thread sample shows it very clearly Steve.  Noise.  Until that is gone (and 
>encoder A output could have a closer to 50% duty cycle too, I'd almost return 
>that one in fact if its sealed and non adjustable), it isn't going to work, 
>not even if we make sacrifices. :)
>
>I have to assume the encoders cabling is shielded, and the shield ends at the 
>encoder so there is no connection via the shield to the machine by way of how 
>the encoder is mounted and driven.  That would be what we call a ground loop, 
>and that is usually a no-no. 

Thanks Gene, that gave me clue and I found it - The encoder cable had a
strand from the shield touching the plug at the controller end. Much,
much better now, but still has the odd glitch, from where I don't know.
disconnecting all the grounds didn't get rid of it.

As for the 50% duty cycle, can't do anything about that other than
replace the encoder.

But - running at slow speed it's MUCH better, and running my test 1.5mm
pitch test file at my normal 700 rpm it's not noticeable at all.

Have a look at the difference :)

http://filebin.ca/brcenc/encoder.pdf


Steve Blackmore
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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Eric H. Johnson]

Peter,

>> Heres what I would check:

Can you get a HALScope plot of the step response? <<

Yes, but not until Monday when I will be back at the shop.

>> Do you have velocity or torque mode amplifiers? 

(Torque mode amplifiers will typically require a higher sample rate and are 
tougher to tune)
your .6" error even with a P of 20 suggests torque mode to me. <<

Velocity 

If it is of any value, although I know they are not directly comparable, the
PID values when using the Galil controller were:

P: 94.25
I: 0.6
D: 1005.63 

>> What number of counts generates a full scale drive (+- 10V) with your
current 
P setting? (Disconnect analog out from amps and measure voltage versus error

counts) <<

Again I can get that for you on Monday.

Thanks again,
Eric


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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Peter C. Wallace]

On Sat, 3 Oct 2009, Eric H. Johnson wrote:

> Date: Sat, 3 Oct 2009 16:14:20 -0400
> From: Eric H. Johnson 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: "'Enhanced Machine Controller (EMC)'" 
> Subject: Re: [Emc-users] PWM tuning with hostmot2 and 7i33
> 
> Peter,
>
>>> Heres what I would check:
>
> Can you get a HALScope plot of the step response? <<
>
> Yes, but not until Monday when I will be back at the shop.
>
>>> Do you have velocity or torque mode amplifiers?
>
> (Torque mode amplifiers will typically require a higher sample rate and are
> tougher to tune)
> your .6" error even with a P of 20 suggests torque mode to me. <<
>
> Velocity


So how can a .6"  error which must be a large number of encoder counts not 
generate even a small velocity to correct the error, something is really wrong 
here...

Peter Wallace
Mesa Electronics

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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing

[Steve Blackmore]

On Fri, 2 Oct 2009 16:14:49 -0500, you wrote:


>I see a use for both systems.  I see that you strongly prefer one over
>the other.  I do not understand yet why you object so strongly to the
>second one being added.

Ahh - it's a second one being added not a replacement for the existing,
even though it's an obsolete Fanuc foible? 

If you're up to adding second commands, there should be no objection
then to adding a current Fanuc lathe command like G32 with F for the
feed word that also does taper threads properly (along the Z axis NOT
the hypotenuse) in addition to the G33 ;)

Steve Blackmore
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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Peter C. Wallace]

On Sat, 3 Oct 2009, John Thornton wrote:

> Date: Sat, 03 Oct 2009 14:26:19 -0600
> From: John Thornton 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: Enhanced Machine Controller EEMC" 
> Subject: Re: [Emc-users] PWM tuning with hostmot2 and 7i33
> 
> Ok, I think I understand now. So somethin to imput a change in the commanded 
> position
> with a trigger for the scope and watch the commanded vs the actual position 
> to tune that
> drive. How big of a step would you take?
>
> Thanks
> John

Big enough so the encoder resolution and any mechanical backlash are 
swamped out by the size of the move say a 1/4 inch or so. Depending on the 
exact drive/mechanical characteristics, you may need to limit the acceleration
to prevent damage

>
> On 3 Oct 2009 at 10:35, Peter C. Wallace wrote:
>
>>
>> Either a gcode or HAL test setup that can take a step (instant jump
>> in
>> commanded position) so the step response of the servo can be
>> captured via
>> HALScope. I cant really imagine hand tuning without being able to
>> see a plot
>> of the servo systems step response.
>>
>> Peter Wallace
>> Mesa Electronics
>>
>
>
> --
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Peter Wallace
Mesa Electronics

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Re: [Emc-users] PWM tuning with hostmot2 and 7i33

[Eric H. Johnson]

Peter,

Exactly, which is why by the end of the day yesterday I was strongly
suspecting that I had screwed up someplace separate from PID tuning, like
MAX_VELOCITY, MAX_ACCELERATION the relationship to input and output scales.
Although I already rechecked those and they seem to be correct. I will dig
back into it on Monday.

Regards,
Eric


So how can a .6"  error which must be a large number of encoder counts not
generate even a small velocity to correct the error, something is really
wrong here...



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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing

[Chris Radek]

On Sat, Oct 03, 2009 at 09:21:43PM +0100, Steve Blackmore wrote:
> 
> Ahh - it's a second one being added not a replacement for the existing,
> even though it's an obsolete Fanuc foible? 

I thought that was clear from the start.

> If you're up to adding second commands, there should be no objection
> then to adding a current Fanuc lathe command like G32 with F for the
> feed word that also does taper threads properly (along the Z axis NOT
> the hypotenuse) in addition to the G33 ;)

No I wouldn't object to someone adding G32.  Do you plan to contribute
this?  I'd happily review this contribution.


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[Emc-users] Line Filters

[Andy Pugh]

Are RFI filters for inverters generally incompatible with RCDs? I
fitted one to my machine today to try to get rid of the noise from the
VFD which seems to interfere with my encoders and limit switches,
however every time I power up the VFD the lights go out and the power
goes off.

The garage and shed are fed though a 30mA RCD (a requirement for power
to a shed AFAIK) and that seems to take offence to the Filter. The
filter is marked "nominal leakage curent 20mA" which might be a clue.

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Re: [Emc-users] Wrapped rotary axes, Fanuc style: for testing

[Steve Blackmore]

On Sat, 3 Oct 2009 16:59:36 -0500, you wrote:

>On Sat, Oct 03, 2009 at 09:21:43PM +0100, Steve Blackmore wrote:
>> 
>> Ahh - it's a second one being added not a replacement for the existing,
>> even though it's an obsolete Fanuc foible? 
>
>I thought that was clear from the start.

No - it wasn't.

>> If you're up to adding second commands, there should be no objection
>> then to adding a current Fanuc lathe command like G32 with F for the
>> feed word that also does taper threads properly (along the Z axis NOT
>> the hypotenuse) in addition to the G33 ;)
>
>No I wouldn't object to someone adding G32.  Do you plan to contribute
>this?  I'd happily review this contribution.

Yes - how do I go about it.

Steve Blackmore
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Re: [Emc-users] Line Filters

[Steve Blackmore]

On Sat, 3 Oct 2009 23:29:15 +0100, you wrote:

>Are RFI filters for inverters generally incompatible with RCDs? I
>fitted one to my machine today to try to get rid of the noise from the
>VFD which seems to interfere with my encoders and limit switches,
>however every time I power up the VFD the lights go out and the power
>goes off.
>
>The garage and shed are fed though a 30mA RCD (a requirement for power
>to a shed AFAIK) and that seems to take offence to the Filter. The
>filter is marked "nominal leakage curent 20mA" which might be a clue.

I just use a 40A Type 3 MCB, on the circuit for the machines, works
fine. I have a 20A RCD which just goes to one double socket near the
shop door, that's used for outdoor or portable equipment.

Steve Blackmore
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[Emc-users] Shutdown event

[Frank Tkalcevic]

I'm writing a python user component to display data on an LCD.  It all works
fine except when Axis/Hal shuts down, the LCD is left displaying whatever
was there last.  Is there a signal/event/pin that I can action off to clear
the display before shutting down?

The python user component talks to a C++ user component which controls the
LCD.  This seems to disappear first in shutdown order, so I need an earlier
notification.  Changing the C++ component to always clear on shutdown is an
option, but I'd rather not force it do the clear.

I'm using the python hal and emc components.

Thanks,
Frank


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Re: [Emc-users] Encoders

[Gene Heskett]

On Saturday 03 October 2009, Steve Blackmore wrote:
>On Fri, 02 Oct 2009 15:24:24 -0400, you wrote:
>>Page 5 and 6 show it but not at a good time scale, page 7 from the base
>>thread sample shows it very clearly Steve.  Noise.  Until that is gone
>> (and encoder A output could have a closer to 50% duty cycle too, I'd
>> almost return that one in fact if its sealed and non adjustable), it
>> isn't going to work, not even if we make sacrifices. :)
>>
>>I have to assume the encoders cabling is shielded, and the shield ends at
>> the encoder so there is no connection via the shield to the machine by
>> way of how the encoder is mounted and driven.  That would be what we call
>> a ground loop, and that is usually a no-no.
>
>Thanks Gene, that gave me clue and I found it - The encoder cable had a
>strand from the shield touching the plug at the controller end. Much,
>much better now, but still has the odd glitch, from where I don't know.
>disconnecting all the grounds didn't get rid of it.
>
>As for the 50% duty cycle, can't do anything about that other than
>replace the encoder.
>
>But - running at slow speed it's MUCH better, and running my test 1.5mm
>pitch test file at my normal 700 rpm it's not noticeable at all.
>
>Have a look at the difference :)
>
>http://filebin.ca/brcenc/encoder.pdf
>
That looks better, but something is still giving the encoder.0.velocity a big 
kick occasionally.  One page one it almost corresponds  to the single pulse 
in the bottom, white trace that I don't see a caption for, and looks like its 
quite close to the edge of the non-50% A trace.  Except for that big spike, 
which corresponds to a single pulse, not a dual pulse, in the bottom trace 
for each half cycle of the encoder b signal.

The expanded version on page 6 looks as if its working there.
>
>Steve Blackmore
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Re: [Emc-users] Line Filters

[Gene Heskett]

On Saturday 03 October 2009, Andy Pugh wrote:
>Are RFI filters for inverters generally incompatible with RCDs? I
>fitted one to my machine today to try to get rid of the noise from the
>VFD which seems to interfere with my encoders and limit switches,
>however every time I power up the VFD the lights go out and the power
>goes off.

Andy, Is your 'RCD' the same as what we call GFCI, ground fault current 
interrupter over on this side of the pond?

>
>The garage and shed are fed though a 30mA RCD (a requirement for power
>to a shed AFAIK) and that seems to take offence to the Filter. The
>filter is marked "nominal leakage curent 20mA" which might be a clue.

20 to 30 ma can be fatal under the right conditions, our GFCI's normally trip 
at about 20 microamps IIRC.



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Re: [Emc-users] Encoders

[Andy Pugh]

2009/10/4 Gene Heskett :

> That looks better, but something is still giving the encoder.0.velocity a big
> kick occasionally.

I think those are on the occasions that both channels change state in
the same sample. That does mean infinite velocity, after all. (Does
the encoder code cap velocity at 1/base thread frequency?)

I suspect that is due to aliasing and the short duty-cycle of the A
channel. Occasionally you get unlucky with the sample frequency and
catch both changing at the same time.

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Re: [Emc-users] Line Filters

[Andy Pugh]

2009/10/4 Gene Heskett :

> Andy, Is your 'RCD' the same as what we call GFCI, ground fault current
> interrupter over on this side of the pond?

Probably. It checks current balance between neutral and live.

> 20 to 30 ma can be fatal under the right conditions, our GFCI's normally trip
> at about 20 microamps IIRC.

These are intended to spot cable damage or live to earh faults, rather
than save you from grabbing live, as I understand it.

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Re: [Emc-users] Encoders

[sam sokolik]

when you get a chance - try the interpolated output from the encoder.

sam

Steve Blackmore wrote:
> On Fri, 02 Oct 2009 15:24:24 -0400, you wrote:
>
>   
>> Page 5 and 6 show it but not at a good time scale, page 7 from the base 
>> thread sample shows it very clearly Steve.  Noise.  Until that is gone (and 
>> encoder A output could have a closer to 50% duty cycle too, I'd almost 
>> return 
>> that one in fact if its sealed and non adjustable), it isn't going to work, 
>> not even if we make sacrifices. :)
>>
>> I have to assume the encoders cabling is shielded, and the shield ends at 
>> the 
>> encoder so there is no connection via the shield to the machine by way of 
>> how 
>> the encoder is mounted and driven.  That would be what we call a ground 
>> loop, 
>> and that is usually a no-no. 
>> 
>
> Thanks Gene, that gave me clue and I found it - The encoder cable had a
> strand from the shield touching the plug at the controller end. Much,
> much better now, but still has the odd glitch, from where I don't know.
> disconnecting all the grounds didn't get rid of it.
>
> As for the 50% duty cycle, can't do anything about that other than
> replace the encoder.
>
> But - running at slow speed it's MUCH better, and running my test 1.5mm
> pitch test file at my normal 700 rpm it's not noticeable at all.
>
> Have a look at the difference :)
>
> http://filebin.ca/brcenc/encoder.pdf
>
>
> Steve Blackmore
> --
>
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>   
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Re: [Emc-users] Encoders

[Andy Pugh]

2009/10/4 sam sokolik :
>
> when you get a chance - try the interpolated output from the encoder.

He already has, though perhaps not since fixing the noise.

-- 
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Re: [Emc-users] Line Filters

[Jon Elson]

Andy Pugh wrote:
> Are RFI filters for inverters generally incompatible with RCDs?
Yes, they can be.  Boxed RFI filters have capacitors to ground, so 
necessarily
they divert some mains current to safety ground.  If that current is above
the threshold of the RDC, it has to trip.  You might be able to find a 
medical-grade
filter or some other with extra-low ground current.

Jon

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Re: [Emc-users] Encoders

[Jon Elson]

Andy Pugh wrote:
> 2009/10/4 Gene Heskett :
>
>   
>> That looks better, but something is still giving the encoder.0.velocity a big
>> kick occasionally.
>> 
>
> I think those are on the occasions that both channels change state in
> the same sample. That does mean infinite velocity, after all. (Does
> the encoder code cap velocity at 1/base thread frequency?)
>
> I suspect that is due to aliasing and the short duty-cycle of the A
> channel. Occasionally you get unlucky with the sample frequency and
> catch both changing at the same time.
>   
That represents an illegal transition, and should be rejected.  At the 
worst case,
it could trick the logic into altering the position by 4 counts.  If 
there is a burst
of noise on both A and B at the same time, it could maybe cause more counts
than that to accumulate.  Have you tried putting pull-up resistors on 
the A and B
lines?  I think you have made progress, but it looks like this is not 
yet working
well enough for machining.


Jon

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Re: [Emc-users] Line Filters

[Gene Heskett]

On Saturday 03 October 2009, Andy Pugh wrote:
>2009/10/4 Gene Heskett :
>> Andy, Is your 'RCD' the same as what we call GFCI, ground fault current
>> interrupter over on this side of the pond?
>
>Probably. It checks current balance between neutral and live.
>
>> 20 to 30 ma can be fatal under the right conditions, our GFCI's normally
>> trip at about 20 microamps IIRC.
>
>These are intended to spot cable damage or live to earh faults, rather
>than save you from grabbing live, as I understand it.

Well, in any event, a large amount of capacitance (without some you don't 
have a filter) has been known to trip our GFCI devices.  Possibly your RCD is 
sensitive to that too.

But not being familiar with your version of the NEC, anything I'd say is a 
SWAG (Scientific Wild Assed Guess) anyway. :)

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Re: [Emc-users] Encoders

[Gene Heskett]

On Saturday 03 October 2009, Steve Blackmore wrote:
>On Fri, 02 Oct 2009 15:24:24 -0400, you wrote:
>>Page 5 and 6 show it but not at a good time scale, page 7 from the base
>>thread sample shows it very clearly Steve.  Noise.  Until that is gone
>> (and encoder A output could have a closer to 50% duty cycle too, I'd
>> almost return that one in fact if its sealed and non adjustable), it
>> isn't going to work, not even if we make sacrifices. :)
>>
>>I have to assume the encoders cabling is shielded, and the shield ends at
>> the encoder so there is no connection via the shield to the machine by
>> way of how the encoder is mounted and driven.  That would be what we call
>> a ground loop, and that is usually a no-no.
>
>Thanks Gene, that gave me clue and I found it - The encoder cable had a
>strand from the shield touching the plug at the controller end. 

Ideally it should be connected solidly at the controller, and not connected 
at the encoder end unless the encoder mount is isolated from the machine. 
Shielding carried into the encoder housing is a good idea, as long as it 
doesn't have a connection to the shaft or the mounting.

All shielding should be connected to the controller.  I ran a piece of 12 
gauge copper wire around the outside of the box I made for my xylotex 
controller, it is tied to the - rail of the motor psu, all motor cable 
shields are tied to it, and of course the ground wire from the computers 
parport is also tied there, all solidly soldered with a silver bearing 
solder, 3% silver I think, the rest the usual eutectic blend.

Motor cables, and interconnect cables for the spindle VSR control (a 
PMDX-106, works great) are all in a microphone cable that Belden calls 'star-
quad', which has 4 wires and a mylar foil shield covered with about a 96% 
tinned copper braid.  Very good cable IMO.

This sets up what we call a star ground system, where every signal ground in 
the system comes to one common point.  Any currents that flow, because there 
is only one common point, cannot develop a stray signal due to the resistance 
or inductance of the ground because everything is referenced to that one 
common point, in this case about 8" of 12 gauge bare wire so there is room to 
solder all the shields to it.

I think it works well, I have used an optical probe to scan surfaces as 
described by one of the guys here, several times and the biggest error is the 
sideways slop in my probe, it may flex or take up the slack in the slip 
tubing as it slides downhill on a curved surface.

>Much,
>much better now, but still has the odd glitch, from where I don't know.
>disconnecting all the grounds didn't get rid of it.
>
>As for the 50% duty cycle, can't do anything about that other than
>replace the encoder.
>
>But - running at slow speed it's MUCH better, and running my test 1.5mm
>pitch test file at my normal 700 rpm it's not noticeable at all.
>
>Have a look at the difference :)
>
>http://filebin.ca/brcenc/encoder.pdf
>
>
>Steve Blackmore
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>
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