Re: [ATM] figuring an ultra-thin 16" mirror

["Jerry B. Hillman" <JBHillman@ev1.net>]

Hi Yan,
I just finished a 16.5" F4.5 mirror.  Center thickness is .5"  Edge
thickness is just under .75" so I have finished a duplicate of the mirror
you are working on.
1st.  I did the entire mirror with the mirror on the bottom. From Hogging to
final figuring.
2nd.  Support is critical.
3rd. Rotation is critical.

Figuring stroke I used.  Mirror on bottom,  8" pitch lap. Texereau method B.
Page 97. Pitch lap size is important. If it is too large, it won't work.  If
you start turning the edge, lengthen the strokes.  Do short sessions, test
often, use Focault and Ronchi testing.  A mirror this size and speed is
difficult to test.
I hope this helps. If not, contact me.  I may have more suggestions
depending on what you are doing.  Every detail is important.
Clear skies, Jerry


_______________________________________________
ATM mailing list http://www.atmlist.net/