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


The base must be curved, otherwise you get uneven pitch thickness which
makes for variation in how it behaves.  Thick pitch behaves like soft
pitch, i.e. it flows more.  If the thickness varies, so does the flow rate,
and it makes it difficult to regulate and figure with. removing the pitch
is not a major chore.  Cover the floor with newspaper to catch chips and
scrape it off, or warm it and scrape it off.  The residual pitch will come
off with turps.  Easy.

colin

-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of Vero
and Lisa Joseph
Sent: Tuesday, January 14, 2003 6:52 AM To: atm{at}shore.net
Subject: ATM Base for polishing lap



G'Day All
After two years off and on (_far_ more off than on!) I have finished fine
grinding my 300mm dia 30mm thick plate glass blank to a FL of 1900mm
(f6.3). The grinding was carried out on a full size 80mm thick concrete and
tile tool. This is my first tile tool after completing previous mirrors on
a glass tool. With these I have used the glass tool as the foundation for
my pitch lap. This time however I would like to preserve the tiled surface
as I do not relish romoving pitch from such a surface in case I have to go
back to grinding. I was going to build a lap base out of plywood when the
thought occurred to me touse the base of my tile tool (ie upside down) to
pour the pitch onto.

My question is - does the surface of the lap base need to have a convex
curve or will the flat bottom of my tile tool suffice? Thank you in advance
for any replies.

Vero Joseph
Goulburn, NSW, Australia (currently under strict water restrictions as
99.6% of the state is affected by the worst drought on record)

--- BBBS/NT v4.00 MP