Original poster: "huil888" <huil888@xxxxxxxxxxxx> Gerry -I should have been more specific. Some of the problems you will encounter when machining fiberglass-epoxy composite material include:
1. Extreme tool wear. The only suitable cutting tools are solid tungsten carbide or diamond. My experience has been that even high quality tool steel loses its edge after very limited cutting, regardless if it has TiN or other anti-wear coatings. Of course, it all depends how much material you are removing. A TiN coated drill bit may "survive" 10 holes, but look at the cutting edge under a microscope and it will be in sad shape.
2. The "swarf" (cuttings) are extremely abrasive, and machine tool ways (when using a milling machine or lathe) must be covered and equipped with a vacuum pick-up right at the cutting tool, and everything must be meticulously cleaned after any machining of fiberglass/epoxy.
3. Any airborne particles (both fiberglass and the epoxy matrix) are very irritating to the skin, and frequently cause skin sensitization after repeat exposures.
4. If the material is overheated by the use of dull cutting tools, the epoxy decomposes and releases noxious fumes. Phenolic material will do this also, but to a lesser extent.
Etc, etc. Regards, Scott ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx> To: <tesla@xxxxxxxxxx> Sent: Tuesday, March 06, 2007 10:09 PM Subject: Re: G10
Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx> Hi Scott,I didn't find it harder to machine G10. That part went just fine. The problem is: G10 is very hard on the tools. It dulls HSS very quickly. TIN coated cobalt hold up just fine.GerryOriginal poster: "huil888" <huil888@xxxxxxxxxxxx> Gates -"G-10" is not a phenolic-based material, it is a very difficult to machine fiberglass-reinforced epoxy composite. For fabricating a disk for a rotary spark gap, you want to use linen or cotton fabric reinforced phenolic composite, type "LE" or "CE".McMaster-Carr (mcmaster-carr.com) stocks 12" X 12" slabs of linen and cotton-reinforced phenolic material (as well as fiberglass G10 material ) in a range of different thicknesses, including 1/4", 3/8" and 1/2" at reasonable prices. They can ship next-day.M-C's brand of linen-reinforced phenolic composite is called "Garolite CE". A 12" X 12" X 3/8" slab of CE material is around $23 plus shipping.Regards, Scott Hanson ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx> To: <tesla@xxxxxxxxxx> Sent: Saturday, March 03, 2007 1:42 PM Subject: G10Original poster: "Gates" <ryker@xxxxxxx> Hey Gang Does anyone out there have a spare piece of Phenolic for my RSG disk? I would need a piece 8"x 8" 1/4" to 3/8" thick. Thanks Gates L