Re: [CAD_CAM_EDM_DRO] Re: Tuning EMC

mjf462001 wrote:

> John thank you for the reply.
>
> I am using 320 gecko drives, and I was able to cure the "backlash"
> problem by tuning the deadband.
>
> my servo motors are just sitting on the bench right now. I want to
> make darn sure they are tame before I mount them on the machine
>
> I am still having problems with the MDI. I request a g91 x1. and the
> motor only moves between .100 and .200" (no following error though)
>
> I don't use steppermod because it couldn't handle the input output
> resolution of 10,000 (250 cpr, 2:1 belt reduction, 5 tpi leadscrew)
> (the computer is really sluggish even the mouse moved really slow)

At this resolution, I think you need a servo-to-go card and analog-input
servo amps, or my universal stepper controller card, which will hook up
to the Gecko drives. If you want 120 IPM feedrates, that is 10,000 * 2 =
20,000 pulses/sec per axis.

> I am running a 650 athlon with lots of memory. but my motors seem to
> starve for input when I ask for more than 35 imp of max velocity.

now, 35 IPM = .583 IPS, x 10,000 = 5833 steps/second, which a
650 Mhz CPU should be able to handle. Steppermod actually handles
high resolutions better than freqmod, so everything you have told me
seems backwards. If you tune steppermod correctly, it definitely should
work. You have to remove the PERIOD=xxx line from the .ini file, and
the INPUT_SCALE and OUTPUT_SCALE values have to be the same,
I think.

> final question
> what could cause my motors to jump when I turn off the power supply?

The collapsing magnetic field when the primary winding is disconnected
from the line causes a high voltage to be developed, and it can transmit
a glitch to circuitry. You should probably have e-stop circuitry that disables
the drivers before you power the supply off.

Jon