Re: Rotary Gap
From: Kenneth Pryor[SMTP:pryor-at-mmsi-dot-com]
Reply To: pryor-at-mmsi-dot-com
Sent: Monday, August 04, 1997 6:30 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
> > Even small flaws from drilled or tapped holes will develop into
> > 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
> > glass epoxy. G-11 has a little better heat resistance but is quite a
> > more expensive. IMHO there is no better material for rotors except
> > steel or aluminum which leaves one with the added problem of
> > the rotor from the motor. Lexan can be used, but melts at a much
> > 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
> > with no problems. A couple years ago while prototyping a 10"
> > gap, I crashed and dead stopped a G-10 rotor with 1/2" tungsten
> > from 3600 RPM on a 2 HP motor. The rotor was trashed because of
> > around the stud holes but was otherwise intact. The stuff is just
> > 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
> works out to several hundred dollars! Sooo I'll probably use lexan.
> Thanks for your help!
> Frankensteins Helper
Just a little warning about using Lexan (polycarbonate) . Do not allow
any Loctite or
any other cyanoacrylic to come in contact with polycarbonate! Even the
will cause the poly to become brittle and crack under the slightest
stress. In a rotating
part this could be quite disconcerting.
Kenneth C. Pryor
Modular Mining Systems
3289 E. Hemisphere Loop
Tucson, AZ 85706