[ATM] Gears for rough grinding

[artbianconi@blast.net]

A cast iron flange is a fine for rough grinding but a cast iron gear 
isn't.

The difference being that the involutes of the gear and adjoining 
surfaces are hardened. It's purposely treated this way to prevent the 
very wear you wish to induce.

Since the gear is not wearing down to make full contact, there is 
little surface area in contact with the glass thus not much abrasive 
being used.

Toss the gear. Get a regular pipe flange (4"?), a short nipple to use 
as a handle and a PVC cap to fit snugly on the nipple so the pipe 
threads don't dig into your palms. All available for peanuts at 
Loew's, Home Depot, Ace Hardware, et al. 

Art Bianconi

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Message: 8
Date: Mon, 29 Mar 2004 16:55:31 -0800 (PST)

I asked whether it was ormal for 3 hours of machine grinding/hogging 
with a cast iron gear and #60 grit to produce at MOST a 0.002" 
depression on a 16.5" plate glass mirror blank. The gear weighs about 
5 pounds, I guess. 

Any comments?

Guy Brandenburg
NCA, NOVAC

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