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

Hi Tom,

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.

John Guenther
Sterling, Virginia

> -----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
>
>
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