Re: Rotary Gap

From: 	RODERICK MAXWELL[SMTP:tank-at-magnolia-dot-net]
Reply To: 	tank-at-magnolia-dot-net
Sent: 	Sunday, August 03, 1997 6:31 PM
To: 	Tesla List
Subject: 	Re:  Rotary Gap

> Rod,
> DO NOT, under any circumstances use acrylic plastic ( plexiglas ) for a
> spark gap rotor. Acrylic cracks and shatters rather easily and is an
> accident waiting for a place to happen when used as a rotary gap rotor.
> Even small flaws from drilled or tapped holes will develop into cracks
> as the material ages. Just the thought of a plexiglas rotor makes me
> shudder!
> I build and sell rotary gaps and the only material I ever use is G-10
> glass epoxy. G-11 has a little better heat resistance but is quite a bit
> more expensive. IMHO there is no better material for rotors except for
> steel or aluminum which leaves one with the added problem of insulating
> the rotor from the motor. Lexan can be used, but melts at a much lower
> temperature than G-10 and overheated rotor studs can work loose. I
> regularly spin the 10" rotor on the series rotary gap I use on my
> magnifier at 7600 RPM or better ( verified with an infrared strobe tach)
> with no problems. A couple years ago while prototyping a 10" synchronous
> gap, I crashed and dead stopped a G-10 rotor with 1/2" tungsten studs
> from 3600 RPM on a 2 HP motor. The rotor was trashed because of cracks
> around the stud holes but was otherwise intact. The stuff is just about
> bullet proof!
> So, if you want to do it safely, spring for the bucks for a piece of
> G-10 or for a few bucks less a piece of Lexan, but please don't use
> plexiglas.
> Safe Coiling,
> Ed Wingate

   Thanks for keeping me out of harms way! The only place that I have
found that sells G-10 is a plastics company that I buy my poly, and
epoxy from. They only sell the stuff in 24" x 48" sheets, and the price
works out to several hundred dollars! Sooo I'll probably use lexan.
Thanks for your help!

                              Frankensteins Helper