Re: ATM Re: [atm_free] Stubborn 1/2 " edge zone

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

I'd suspect that with two firm ROCs that the lap has a depressed center on
it.  This produces an outer zone that is what you are working while the
inner zone is just floating along.  This produces a long inner zone which is
what I suspect you have as you didn't say.
Try a very warm press for a start and then make sure that the whole lap is
in good contact.  Don't use a lot of CeO when checking as that can and will
hide where the problems are.  Then do a regular 1/3 stroke for about 10
minutes and do a short warm press to get the lap back into compliance with
the central zone.
Two zones like that need a good regular 1/3 stroke that makes a nice sphere
first.
If the inner zone is shorter, then you aren't working the outer zone even
with the TOT and that means that you are going to have to work the outer
parts of the mirror with the lap with a more chordal stroke otherwise the
center will work out to near the edge and you will have a TDE that will take
a while to work out.
Sometimes I will take a small lap (maybe 1" or so) and work the high area
all by itself to get it down to where the full lap can smooth things out.
Hope this helps.  If anybody else knows anything better to do, advice is
always welcome to give their opinion on this one.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net