Re: ATM How many times do I need to do this??!!

["Bob May" <bobmay@nethere.com>]

Try a 1" diameter subdiameter tool and rub it where the glass is high and
you will quickly see those places go lower.  That, followed by a tool of a
little bit less than 1/4 of the diameter of the mirror will come next to
even things out to where you have a 1/4 wave sphere will make the full sized
lap finish up the problems quick. Go for a sphere first before you try going
to a parabola and things will be best.
Each of the tools must match the ROC of the mirror and that means that you
want to pour warm water on the tool until you can dent just the surface of
the pitch with your finger, stopping the fingernail just a little bit in and
then quickly applying the lap to the mirror and getting the two surfaces to
match well.  Remember that you're working with sub lightwave clearances when
doing this!
The good working of the glass will keep the temps into the region where you
can keep the pitch mated to the glass and that is why the grooves in the
pitch as much as anything else.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net