Re: RSG Disk Material

["Tesla list" <tesla@pupman.com>]

Original poster: "Mike Novak by way of Terry Fritz <twftesla@uswest.net>" <acmnovak@email.msn.com>

Steve,
I think you should just use the cheap low grade stuff. CE or LE will do just
fine. Bill Wyestock of TTR.com uses CE for his commercial SRSGs and they run
at 3600 RPM with some rather beefy electrodes.
The price difference is ssomething to consider as well...
My $0.02

-Mike

----- Original Message -----
From: Tesla list <tesla@pupman.com>
To: <tesla@pupman.com>
Sent: Tuesday, December 19, 2000 10:30 PM
Subject: RSG Disk Material


> Original poster: "Steve & Jackie Young by way of Terry Fritz
<twftesla@uswest.net>" <youngs@konnections.com>
>
> Dear RSG builders,
>
> I want to know why I shouldn't use GP03 (electrical grade figerglass)
instead
> of the more expensive G-10 (Garolite)?  As Dan points out below, the G-10
has 4
> times the tensile strength, but about 4 times the cost and about
two-thirds the
> high temp rating.  At what rotor electrode velocity will 10,000 PSI
tensile
> strength not be adequate to keep the electrodes from becoming projectiles
as
> the RSG flies apart?  I like the cheaper price of GP03, and being able to
cut
> it with non-carbide tools.
>
> Your thoughts on GP03 vs G-10 will be appreciated.
> --Steve
>
> Back in April, Dan posted the following (the prices are still the same
today):
>
> "Here's some material offered by McMaster-Carr I've been thinking about
> using for SRSG rotors.
>
> A 1/2" thick, 12" x 12" square is $12.54
>
> Electrical Grade Fiberglass (GP03)
> . Color: Opaque red
> . Temp. Range: 0° to 400° F
> . Tensile Strength: Excellent
> Enhanced electrical insulation properties and a flame-resistant additive
> make this material ideal for electrical applications. It is a glass
> fiber-reinforced polyester. Material meets UL-94V0 standards.
> . Impact Strength: Excellent
> . Excellent electrical insulator
> . Use indoors
> . Easy to machine
>
> Notice that the temperature goes to 400° F, and it's listed as easy to
> machine.
>
> Other specifications:
>
> Tensile Strength: 10,000 psi
> Impact Strength: 8.2 ft.-lbs./in.
> Dielectric Strength: 400 V/mil
> Tracking Index: 500 volts
> Durometer: Barcol 50
> Coefficient of Thermal Expansion: 2.010 -5 in./in./°C
> Weather Resistance: Material is not weather resistant. Resin will break
> down over long periods of exposure to the outdoors.
>
> Processing--
>
> Machinability: Can be easily machined. Can be cut with a hacksaw, diamond
> grit saw blade, and carbide tip saw blade. Holes are easily created using
> conventional drill bits and milling bits. A dust mask and gloves should be
> worn when working on this material.
> Welding: Not recommended.
> Scratch Resistance: Moderate.
> Chemical Resistance: Use with mild detergents. Do not use with strong
acids.
>
> The original GP03 page is at
>
<http://www.mcmaster.com/pdf/106/3088.pdf>http://www.mcmaster.com/pdf/106/30
> 88.pdf
> The extra specifications are at
>
<http://www.mcmaster.com/pdf/106/8549KAC1.pdf>http://www.mcmaster.com/pdf/10
> 6/8549KAC1.pdf
>
> Here's some G-10/FR4 Garolite specs:
>
> A 1/2" thick, 12" x 12" square is $46.87
>
> . Color: Opaque brownish-green (except where noted)
> . Temp. Range: 0° to 284° F
> . Tensile Strength: Excellent
> An outstanding electrical insulator, this continuous-woven glass fabric
> lami-nated with an epoxy resin absorbs virtually no water and offers good
> dimen-sional stability. Meets UL-94V0 standard for flame resistance unless
> noted.
> . Impact Strength: Excellent
> . Excellent electrical insulator
> . Use indoors
> . Difficult to machine
>
> Notice that the temperature goes to 284° F, and it's listed as difficult
to
> machine.
>
> Other specifications:
>
> Meet the following standard: UL94V-0 for flammability and Mil l 24768/27.
> Tensile Strength: 40,000 psi
> Impact Strength: 7 ft.-lbs./in.
> Dielectric Strength: 500 V/mil
> Durometer: Rockwell M: 110
> Coefficient of Thermal Expansion: 1.8210 -5 cm/cm/°C
> Weather Resistance: Material is weather resistant.
>
> Processing--
>
> Machinability: Can be machined using carbide tools.
> Welding: Cannot be welded, but can be glued.
> Scratch Resistance: Material has good scratch resistance.
> Chemical Resistance: Use with dilute acids and some organic solvents. Do
> not use with acetone, alkalines, and strong acids.
>
> The original G-10 page is at
>
<http://www.mcmaster.com/pdf/106/3092.pdf>http://www.mcmaster.com/pdf/106/30
> 92.pdf
> The extra specifications are at
>
<http://www.mcmaster.com/pdf/106/8667KAC1.pdf>http://www.mcmaster.com/pdf/10
> 6/8667KAC1.pdf
>
> The only real difference I can see, as far as specs are concerned is that
> G-10 has a tensile strength of 40,000 lbs/sq.in., while GP03 has a tensile
> strength of 10,000 lbs/sq.in. Everything else seems very close. The
> difference in tensile strength might matter as far as a rotor is
concerned,
> but I'll still probably try it. For a Scott gap, it should be fine.
> Comments?
>
> Dan
> <mailto:ntesla@ntesla.csd.sc.edu>ntesla@ntesla.csd.sc.edu "
>
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