Re: [CAD_CAM_EDM_DRO] GeckoDrive: seeking practical advice aboutthe Big Capacitor !

Hans Wedemeyer wrote:

>Thanks for all the replies.
>
>Here's what I did since posting the question:-
>
>I wanted to confirm my thoughts that a higher Voltage would cure the problem (see original post), so I rigged a 24 Volt 8 Amp Supply in series with the 36 Volt (8 Amps) (thanks Jon)
>
>Both supplies are Switchers and regulated they only drop a few millivolts at 8 Amps (High $$$ supplies)
>I was surprized even with 60 Volts the problem did NOT go away and then turned my attention to the PIC Pulse generator Software and added a Ramp with three steps (each step has it's own slope adjustment
>and has each slope has 6 Steps).
>By bringing the motor up slowly (1 Second) and then at about 80% I increased drive frequency more slowly (final 1 second) the motor
>now runs fine on 36 Volts under full load.
>
>

Smooth acceleration and deceleration ramps are absolutely ESSENTIAL!
Sharp jumps in speed, or sharp changes in acceleration will cause the
motors to stall or lose steps. Ragged pulse timing will also cause this.
Low-powered CPUs and software timing schemes are usable up to
a couple thousand steps/second, but really start to fall flat in this regard
beyond that. I demonstrated this at the 2001 NAMES show with my
digital step rate generator prototype and a Sherline with MicroKinetics
drivers. Nobody had ever seen one of these machines move over 13 IPM.
I had it running at 25 IPM with little trouble, having never seen that
machine or driver before.

Jon