Re: [ATM] Abrasives

["Thomas Janstrom" <thomas@moiler.com>]

WOOOPS!

My list should have read:
.....
1200 grit SiC
15 Mic AlO
9 Mic AlO
.....

It's still a slight back wards step going from 1200 to 15 mic, but not as
huge as what I originally wrote!

Sorry for any confusion.

Thomas.

-----Original Message-----
From: Michael Lindner [mailto:mikell@optonline.net] 
Sent: Tuesday, 6 March 2007 12:52 AM
To: thomas@moiler.com
Cc: 'Thomas A. Moulton'; 'ATM Superheros'
Subject: Re: [ATM] Abrasives

Thomas Janstrom wrote:
> The grits I use regardless of mirror size are:

FWIW I have tried two extremes (both on pregenerated blanks):

120-320-25u-polish

and

120-220-320-500-25u-12u-9u-5u-3u-polish

and found no difference I could detect in the final surface smoothness. 
The total amount of time spent either way is about the same, as you can 
get by with shorter times with smaller steps between grits. I do find 
that it's fairly easy to get sleeks or scratches below 9u if you're not 
careful. Of course, Mel's done at least 20x as many mirrors as me, so if 
he says don't skip 500, I'd defer to his wisdom.

Clear skies.
-- 
Michael Lindner
http://www.starastronomy.org *** http://home.att.net/~mikel
http://www.atmsite.org *** http://www.atmlist.net
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