RE: Testing Step Motors

I am using (for the time being) Microkinetics Millmaster with their Optistep
driver board. The software is OK but the jog mode does not have ramping.
The large motors will not respond to a step function (instant acceleration)
above crawling speed. Thus, jog spped must be set so low that jogging takes
forever.

I recently got a demo of CNCPro, which is supposed to have ramping in jog
mode. Haven't tried it on the machine yet. The interface seems friendly,
but the G-godes are wierd. I suppose this won't be too much problem if I
can get a post for Mastercam to work with it.

Can you explain what changes you made in software that cured your vibration
problem? We have a second Microkinetics system we want to use on a BOSS-5
and would rather avoid buying new amps (the upgrade period has expired on
this one).

Doug Harrison

> -----Original Message-----
> From: Matt Shaver [SMTP:mshaver@...]
> Sent: Thursday, November 18, 1999 11:10 AM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] Testing Step Motors
>
> From: "Matt Shaver" <mshaver@...>
>
> > From: "Harrison, Doug" <dharrison@...>
> > I recently purchased a Microkinetics Driverack system. Not too happy
> with
> > it, but that's another story. I did, however, learn from first hand
> > experience that microstepping has significant advantages over
> conventional
> > halfstepping when using large (Nema 42) motors. With the old L/R drive
> > amplifiers, such as were found on the BOSS 5 Bridgeport mills, resonance
> was
> > annoying but tolerable. But the newer switching amplifiers are so harsh
> > that these large motors are almost unusable. Microstepping virtually
> > eliminates the vibration. Having started with halfstepping and later
> paid
> > for the upgrade I can vouch for the advantages.
> >
> > Accuracy is not so much an issue as is repeatability. Halfstepping a
> 400
> > cog motor with 1:2 gearing yields .0005 resolution on a knee mill and
> that's
> > well within the repeatability of most low end machines. Repeatability
> > becomes and issue when vibration is so bad the motor skips steps, and
> that
> > is usually why they skip if we are assuming they were of adequate size
> to
> > begin with.
>
> I have recently completed a similar project retrofitting a BOSS machine
> with
> Microkinetics DR8010 drives and keeping the original motors. I had hideous
> problems just as you describe, and I was going to upgrade to the
> microstepping version of the drive. Then I found, through experimentation,
> that it was a software configuration problem.
>
> What software are you using?
>
> Matt
>
> > Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the
> discussion of shop built systems in the above catagories.
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