To: Atm{at}shore.net
From: "David M Groski" 
Reply-To: "David M Groski" 



The secret I found to making a good sphere without going through every
defect in the books is keeping  the channels of the lap open to the same
width.across the diameter of the lap. It does not take long before the
channels will start to close in the center. This causes the surface area of
the lap that is in contact with the mirror to increase which cause more
polishing action. For every 10 to 15 minutes of polishing, I stop and run a
hot soldering iron down the channels so they are at the same width. By
doing this, I do not  have any major surface defects like turn down edge
and it doesn't take a large effort to arrive at a perfect sphere.

               Best Regards,
                   Dave




"mlbrown{at}everstrive.com" {at}shore.net
on 02/11/2003 03:58:32 PM

Please respond to "mlbrown{at}everstrive.com" 

Sent by:    owner-atm{at}shore.net


To:    atm{at}shore.net
cc:
Subject:    Re: ATM Tesing a spheriod



I concur.  I've done about 20 hours just trying to get a 1/4 wave sphere
out of that little 4.25" mirror I've been working on.  I think I've
migrated thru just about every surface defect in the book: turned down
edge, to zonal rings, to hill with crater in middle and turned down edge,
now to turned up edge.  I keep repeating to myself that this hobby both
requires and teaches patience.  I'm close though; any day now...

=Matt


>>>>>Ah, Yes.  Easy to test is right.  I labored through
probably 20 hrs of
figuring to get a good sphere 8" f/15.  I wanted the best reference sphere
<<<<http://mail2web.com/ .








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