Re: [ATM] BVC Mirror Blanks

["Richard Ozer" <rozer@pacbell.net>]

I've been working on a 14" for a while (getting close to done... within a
1/4 wave right now).

Here are my observations in a nutshell:

The material is very soft, softer than plate.
Compared to Pyrex, each grit has the effect of the next larger size.  For
instance, when grinding with 320, the pits look like 220 pyrex pits.
Don't skip grit sizes.  I got a pre-generated blank, started with 120 (the
pre-gen was very rough), then 220, 320, 400, 500, 600, 12micron, 9micron.
Skip the 5micron altogether, it's not helpful on this material (sleeks and
scratches).
Keep your workspace very clean... the scratch factor is very high!
Don't freak out if you see layering in the glass, air between the layers, or
holes in the side of the blank... none of that matters; it just looks weird.

My one big mistake was not grinding the back of the blank flat.  It turns
out that it was not completely flat, and caused some stig as a result.

All in all; I like this material, and it looks pretty neat!

RO

----- Original Message ----- 
From: "Chuck" <cscappaticci@adelphia.net>
To: <atm@atmlist.net>
Sent: Wednesday, July 28, 2004 7:18 PM
Subject: [ATM] BVC Mirror Blanks


Hi, what is the opinion/experience with ASM's BVC mirror blanks.   I heard
that there were some problems at first, but then they were resolved?
Thanks ...   looking at buying a 20" blank ...

Clear Skies,

     Chuck
_______________________________________________
ATM mailing list http://www.atmlist.net/

_______________________________________________
ATM mailing list http://www.atmlist.net/