Square rotor on SRSG

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

Original poster: "Paul Arrowsmith by way of Terry Fritz <twftesla-at-qwest-dot-net>" <p_t_arrowsmith-at-hotmail-dot-com>

I built my SRSG using a square rotor.
The motor is a 6-inch bench grinder motor (modified), the rotor 4 X 150mm 
(6-inch) square P.C.B's with the copper etched off and the 4 board’s 
sandwiched together.
Its works great, the wind drag is not excessively loading the motor.
Advantages of this method are 1. Fraction of the cost of G10 sheet 2. No 
machining required! as the PCB boards purchased from the local Electronics 
Shop were perfectly square, only accurate marking out needed (easy with 
square material as you only need to draw from corner to corner). 3. Extra 
wind may help cool the stationary electrodes. 4. No wastage of materials, 
the rotating electrodes are spaced significantly further apart than if it 
was cut down to a round disk as they are mounted in the corners that would 
normally be scraped. If I was to build a round disk using the same electrode 
spacing a sheet measuring about 40% more across is needed representing about 
twice! the material required.
The only drawbacks I can see is that you are limited to 2 or 4 evenly spaced 
rotating electrodes (4 is a waste of time unless you are going for 4 breaks 
a cycle at .707 of peak or a ARSG), wind drag may be a problem on very large 
rotating squares?
If you are planning a 2 or 4 electrode rotary I recommend a square.
Paul A in Australia