Re: [CAD_CAM_EDM_DRO] Tuning steppers

Matt,
Looking at the step signals, using freqmot, I see the step line toggling
between high and low while outputting step signals. What is going on? If I
put it in jog mode of .01 and jog it I get a normally high with pulses going
low then the next set show normally low with pulses going high.

Darrell

----- Original Message -----
From: Matt Shaver <mshaver@...>
To: <CAD_CAM_EDM_DRO@onelist.com>
Sent: Monday, March 13, 2000 2:05 PM
Subject: Re: [CAD_CAM_EDM_DRO] Tuning steppers


> From: "Matt Shaver" <mshaver@...>
>
> > From: "Joel Jacobs" <jj@...>
> > With the eval CNCpro I could get 30 ipm easy,
> > with emc and freqmot I can barely get 15 ipm - and the motor 'growls' -
and
> > the drivers get quite a bit warmer - due to the not-smooth pulse train.
Now
> > I do only have a pentium 100, and I had to set the 'PERIOD' variable in
> > freqmot from 20 to 100 just to get the GUI working and that may be the
> > problem but how much computer does it take to run a stepper motor?
>
> If you want to run in a windows environment (X or Microsoft), and also
> generate the step pulse train entirely in software, the answer is that it
> takes quite a fast computer. Systems like Ahha, Flashcut, and the
Bridgeport
> BOSS use external pulse generator hardware which frees up a lot of CPU
time.
> Other systems like CNC Pro, Stepster, DanCAM, and DeskNC run under DOS
where
> they execute with 100% priority. Since DOS gives a user program complete
> control over the computer, step pulse generation and user interface
> interaction (limited) can be accomplished simultaneously, although they
won't
> be able to achieve the performance of a system that uses external pulse
> generating hardware.
>
> I've made a spreadsheet that shows the relationship between INPUT_SCALE,
> PERIOD, and the output frequencies available. It's at:
>
> http://users.erols.com/mshaver/stepfreq.xls
>
> > I see there are instructions on linuxcnc.org for installing emc on a
486!
> > How could that possibly work?
>
> It won't work for steppers, it might work OK for a servo system.
>
> > So you guys running emc and freqmot - what speed computers are you
> > running it on? What value 'PERIOD' do you use? I'd like to know what
it's
> > going to take to make this thing work?
>
> I retrofitted a Bridgeport BOSS machine and got 54ipm with an input scale
of
> 4000 using a 350MHzP2 with 128MB of RAM. I think I had PERIOD set to 11 or
> 12.
>
> E-mail me your phone # and I'll give you a call. I bought a board that has
an
> 8254 on it with the idea of integrating it with the EMC software to solve
the
> problem you're having. I might not get around to this for some time and it
> might be a good idea to send you the board to see if it helps you.
>
> Matt
>
>
>
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