From: "CSC" 
To: "Atm" 
Reply-To: "CSC" 


Oh yes, big trouble there.  Let's not introduce more unknown variables into
our work.  Varying pitch thickness is trouble.

Colin

-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of John
Murray
Sent: Monday, June 16, 2003 10:51 PM To: atm{at}shore.net
Subject: RE: ATM Flat 10 incher polishing lap



G'day Kartik,
        What I am thinking though is that you could end up with different
thickness's of pitch between the centre and the edge of the lap. Might this
not possibly have an effect on how the centre and edges of the lap behave?
ie: 1/4" deep at the centre and 1/2" at the edge may press/work
differently due to the edge being thicker.
Cheers

John Murray
Whyalla
South Australia
Check our web page at http://astronomy.sa86net.com ATM and M-O-M stuff.


> You are correct, when poured the hot pitch will definitely flow
> to the edges of the base.
> But in the usual way, there it will be restrained by a dam which
> will block it from flowing off the edge. The surface of the pool
> of pitch, which should be deep enough to cover the raised
> portion, cools rapidly and retains the shape of the blank, as it
> is pressed on. This surface is maintained through repeated cold
> pressing before every polishing session.

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