Re: stepper-servo system

>
> So if voltage of the gap = height (or depth or whatever you call it)
> and the wire cuts the "servo" (reading the voltage would force the
> motor to move down to correct. You are not talking about inches here
> but fractions. Things like acceleration, move rate etc would be close
> to meaningless. The target voltage would determine the speed at which
> it cut and it would move in the correct direction to maintain the
> balance.

I think you've got it.

it is dead simple.

one can do it with a pulse generator from a 555 and an op-amp.

10 volts will jump the gap of some 5 thenths or so, (I have a chart
somewehre) and there is the sweet spot of +/- 5 volts or so where no
action is needed.

movement is in thousandts of a mm so the leadscrew has to be really
fine, or the stepper driver has a high multiplier.

one step can often change the voltage into the 'too close' range, so
sitting there, it will cut, open the gap, let the voltage increase,
and then hit the 'too far' limit.

Screw feed per step and accuracy of the axis are the two super
cirtical things. too coarse and it will dither itself to death and if
the axis has any movement, when you do reverse the screw, you can have
the electrode move sideways, short, and require the whole thing to
back out and approach with the backlash on the feed-in side.

Dave