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Re: Garolite (G9, G10, G11) questions.



Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

Sam,

I have had very good results using GP03 that I got from McMaster-Carr.  a 12
by 12 by 3/8 inch sheet is only about $10.  This is electrical grade
fiberglass.  Tensile strength is 10,000 psi & impact strength of 8.2 ft-lbs.
10,000 psi has been adequate for me as I don't spin my rotors more than
5,000 rpm and the spinning electrodes are light weight.

Another factor to consider is temperature ratings, since the electrodes can
get quite hot.  GP03 is good to 400 degrees F, which is better then G10 (284
degrees F).  Another good feature of GP03 is that it cuts, grinds and drills
well with ordinary metal working tools.  G10 is much tougher stuff and wears
out drill bits and saw blades faster.
--Steve
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, June 08, 2002 1:56 PM
Subject: Garolite (G9, G10, G11) questions.


> Original poster: "Sam Barros by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<list-at-powerlabs-dot-org>
>
>  Greetings,
>
>  This question concerns materials choice for a rotary spark gap.
> Obviously we want the rotor disk to be as light as possible so that
> a smaller motor can be utilized and the spin up time becomes shorter.
> In order for a light disk to withstand the centrifugal forces encountered
> in rotary spark gap duty it would make sense to use the strongest
> material possible (within some price restrictions obviously). I notice
> that G-10 grade Garolite seems to be the most often used material,
> and with a tensile strenght of 40000PSI and an impact strenght of
> 7ft/lbs/in it is definitely a good choice. I also see some designs
> using polycarbonate but at 9000PSI tensile strenght, 12ft/lbs/in
> impact strenght I would definitely go for G-10.
>  However, why doesn't anyone use grade G-9 Garolite? With a tensile
> strength of 66,700PSI lenghtwise and 51,900PSI crosswise, and an
> impact strength of 14.5ft/lbs lenghtwise and 11,2 crosswise, it would
> make a much better material choice for a lighter, stronger rotary
> spark gap disk, no? The price is also virtually the same as G-10
> ($29 for a 1/4in thick, 1'x1' sheet). Also, what about other grades
> of Garolite (G-11, G-30)? They seem to be weaker and more expensive,
> is there any advantage to them? Is there any plastic/composite material
> that is NON CONDUCTIVE and stronger than G-9?
>  Finally, how stiff is G-9? Does it buckle under force or does it
> tend to fracture in a brittle fashion (I am deducing from the relatively
> low impact strength that it will shatter, but I couldn't find its
> modulus of elasticity anywhere)?
>  Any answers to these questions would be greatly appreciated.
>
> Sam Barros
> ME/EE Major at Michigan Tech.
> http://www.powerlabs-dot-org/
>
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