RE: [CAD_CAM_EDM_DRO] EMC, freqmod.o, A-axis, .ini settings, oh my!

On Mon, 19 Aug 2002, j.guenther wrote:

> Welcome to the club!! I have been fighting this problem since the end
> of June with no joy. It appears to be a granularity issue, and the
> lower the steps per unit the worse it gets. I am going to reload my
> EMC setup with BDI 2.16 so I can try it with steppermod.o as I am
> currently running the BDI-TNG which only works with freqmod.o. I
> really wish one of the EMC developers would track this down and fix
> it. I have thought about running mine with input and output scale set
> to 28800, and units set to 1. That way a 90 degree move would be g0
> a0.25 which is not the way I want to run it but does work. Sounds
> like you have a Sherline mill and rotary table. I have the Sherline
> 5400 mill and got the cnc rotary table for my 55th birthday.

Wellll... Almost. I've got a Taig mill, and a Sherline rotary table.
They actually play very well together. The one catch with the Taig mill,
though, is that it doesn't use step/dir, it uses four phase output. EMC
doesn't like to do that, so it took some tweaking on freqmod.o to make it
work.

The upshot of this is that switching to steppermod.o would involve
re-hacking the source to make four phase output work. Hopefully real soon
now I'll be able to afford the electronics to convert step/dir to four
phase output so I can use EMC talking step/dir. That'll also mean I can
run the whole beast off a single parallel port. Some day (hopefully
soon...)

In the mean time I'm trying to get things working. DANG this is driving
me nuts!

If I find anything, I'll let you know.

Tom

> > -----Original Message-----
> > From: Tom Benedict [mailto:benedict@...]
> > Sent: Monday, August 19, 2002 11:24 AM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Subject: [CAD_CAM_EDM_DRO] EMC, freqmod.o, A-axis, .ini settings, oh my!
> >
> >
> > Here's the setup:
> >
> > I've got a stepper-based mill that's got four axes. The A axis is a
> > rotary table that's bolted to the mill bed so the axis points parallel to
> > the X-axis.
> >
> > I'm running the latest rev of the BDI, and the motors are set up to use
> > freqmod.o.
> >
> > I'm trying to tune the .ini parameters for the fourth axis so I can
> > address the rotary table in units of degrees. The linear axes are being
> > addressed in units of inches.
> >
> > I've got 200 step/in motors that are being half-stepped. The linear axes
> > have 20TPI leadscrews, so that winds up being 8000 steps/inch. The rotary
> > axis has a 1:72 worm gear on it, and uses the same motor as the linear
> > axes. So at 5 degrees per revolution of the motor, that's 80 steps per
> > degree.
> >
> > Now for the troubleshooting:
> >
> > I've got the linear axes pretty happy. I don't have my .ini file in front
> > of me, but I use an INPUT_SCALE and OUTPUT_SCALE of 8000.0 0.0,
> > LINEAR_UNITS of 0.03937007874016 in [TRAJ] and UNITS of 0.03937007874016
> > inside each [AXIS_*] section (I'm using inches), and a P of 500.0.
> >
> > I've got ANGULAR_UNITS set to 1.0 in [TRAJ] and UNITS set to 1.0 in
> > [AXIS_3]. With all the other parameters set the same, if INPUT_SCALE and
> > OUTPUT_SCALE is set to 8000.0 0.0, the axis works, but it's not being
> > addressed in terms of degrees. If I change INPUT_SCALE and OUTPUT_SCALE
> > to 80.0 0.0, the axis ceases to function.
> >
> > I've tried dinking with this a fair amount. I can marginally get it
> > working with the SCALEs set to 800.0 0.0, and address it in terms of tens
> > of degrees (so G0 A9.0 would rotate it 90 degrees), but obviously this
> > isn't what I'd like it to do.
> >
> > Has anyone got a stepper system using freqmod.o to work with a rotary
> > axis? Can anyone share a success story that would help me get this thing
> > working?
> >
> > Any and all help is much appreciated.
> >
> > Thanks,
> >
> > Tom
> >
> >
> > Addresses:
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> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this as a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
>
> Post messages: CAD_CAM_EDM_DRO@yahoogroups.com
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> bill,
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