Re: RSG Disk Material

["Tesla list" <tesla-at-pupman-dot-com>]

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

Steve,
I think you should just use the cheap low grade stuff. CE or LE will do just
fine. Bill Wyestock of TTR-dot-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-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, December 19, 2000 10:30 PM
Subject: RSG Disk Material


> Original poster: "Steve & Jackie Young by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <youngs-at-konnections-dot-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-dot-com/pdf/106/3088.pdf>http://www.mcmaster-dot-com/pdf/106/30
> 88.pdf
> The extra specifications are at
>
<http://www.mcmaster-dot-com/pdf/106/8549KAC1.pdf>http://www.mcmaster-dot-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-dot-com/pdf/106/3092.pdf>http://www.mcmaster-dot-com/pdf/106/30
> 92.pdf
> The extra specifications are at
>
<http://www.mcmaster-dot-com/pdf/106/8667KAC1.pdf>http://www.mcmaster-dot-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-at-ntesla.csd.sc.edu>ntesla-at-ntesla.csd.sc.edu "
>
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