Rotary SG???

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "raven0075 by way of Terry Fritz <twftesla-at-uswest-dot-net>" <raven0075-at-home-dot-com>

I am getting a 1/3 HP AC motor , looking at building my first Rotary GAP.
 
I have been browsing allot of the info on Rotary Gap setups.
 
Question 1.
What is the appropriate disk size.
If I am going to run at 1800 RPM do I  use 4 electrodes and at 3600 RPM do I
use 2 electrodes?
And is there any detailed info on where to get a 110V 5-10 amp potentiometer so
I can tune the gap live? Or is this bad on motors.
 
Thanks
Brian W.