[ATM] Sand-blasting a mirror blank

["N1XLP" <N1XLP@triad.rr.com>]

I am currently in possesion of a 24"x5" fused silica, 135 lbs, mirror blank that has the wrong curve on it. 

The current curve is around f/1 (the sagitta is about 1") and I would like to "shave" down the outer zones for the overall shape to come down to about f/5 (target sagitta of .33"). 

I have found a local sand blasting outfit that will do the work for me (quoted me $100 over the phone)and I am wondering about some of the issues with doing this before I start blasting.

I cant see grinding this out by hand. I would have Popeye arms in no time. :-)

Can anyone enlighten me on the techniques, issues, and/or pitfalls? 

TIA!

-Phil
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