Rotary motor plans



I ordered a motor today for my rotary gap.  I went with the 10,000 rpm 1/2
horsepower DC motor.  Using a variac and a full wave bridge, I should be able
to limit the rpm to 5000 or 6000 rpm.  Do you think this will work ok?

I am having an 8.0" diameter disc made of 3/8 lexan as you suggested.  Does
it do any good to make the disc larger, like 10.0"?  I plan to use 8
electrodes like yours using 1/4" stainless acorn nuts on each side.  I have a
piece of 5/32 tungsten for the stationary electrodes.

Thanks,  Ed Sonderman