Re: Rotary Gap
From: Edward J. Wingate[SMTP:ewing7-at-frontiernet-dot-net]
Reply To: ewing7-at-frontiernet-dot-net
Sent: Monday, August 04, 1997 2:45 PM
To: Tesla List
Subject: Re: Rotary Gap
Tesla List wrote:
> 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
Yes, many places only want to sell you a full sheet because they don't
have the diamond saw necessary to efficiently cut the stuff. The dust is
also a health hazard.
Dave Euans in a past post gave the name of a company in Ohio that will
sell you a single square foot of 1/2" G-10 for $38-$40. You might give
them a call.
2554 Needmore Rd.
Dayton, Ohio 45414