Re: [ATM] re: Working with thin mirrors

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

Thanks for the kudos.
I tend to teach a method where the wrists are a bit limp and allow the tool
to turn a few degrees as the stroke is done.  This takes care of 1/2 of the
problem of going around the barrel and then, since there is usually a corner
of a table, the rest of the problem of keeping the rotating going is to
slowly walk around that corner of the table as the strokes are done.  Every
two or so turns around the corner, the mirror gets rotated in its seat
(generally I use a plywood piece with 3 stops that are slotted so they can
be fitted right up to the glass easily for that particular mirror) and the
process continued.   Doing this, I've not seen any astigmatic mirrors done
in my classes.  I have seen some astigmatic mirrors that people have brought
in to be analysed for why they aren't good performers.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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