Re: ATM Updated Page 25" Folded Newt Project

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

Any local optician supply house should have the polishing pads.  A roll of
300 wholesales for about $25 or so.  Buy a roll and spread them out amongst
the other grinders around you and you will all enjoy the initial polishing
process a lot more.
Personally, I prefer the rectangular pads as they provide the ability to
cover more of the tool than the round ones.
There is an almost bewildering array of the pads for various glasses and
speeds.  You want to get the most aggressive polishing ones that the place
recommends as you are interested in doing polishing rather than getting a
really accurate surface.  This sounds contridictory but you have to remember
that the big part is going to be getting the pits out of the surface and a
quick polishing action will do this and later you go with the pitch and you
smooth out the little irregularities with the pitch.  I've never worried
about all of the little rings although the bumpies that some have produced
get taken out before going to pitch do get removed as these come from
improper polishing technique.  The rings are from the speed of the polishing
that can be done and that the pads aren't as compliant as pitch is and thus
there will be high zones of the pads which will make for a zoney surface
which will go away in a few minutes on the pitch.
Also, the seeing of 5 or more zone changes on a surface in the Foucault test
will most assuredly show you that your testing is indeed being done
correctly.  I'll note that not all mirrors will have zones and have even
mostly parabolized a mirror on pads once.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net