[ATM] Small .25-.5" turned edge

["Robert Fifarek" <Roboscope1@cox.net>]

I've been figuring a 16 inch f4 plate glass mirror for some time now. I use
a 9 zone couder mask and Fig XP to check progress on a home made focault
(fixed source) tester. Star test shows definite turned edge, and my latest
readings are as follows:

 

ftp://members.cox.net/16inchno9_23FL_Surface.jpg

 

My question, can this be corrected with a 7.5" figuring lap? I have tried
cordal strokes with a 3 inch lap and finger polishing, but can't seem to get
results on edge correction. The last two figuring sessions I have used the
7.5" lap with just off center (1-2") strokes which seems to be working, but
I thought I would throw this question out the list to see what feedback I
got before I went too far. I know many of you will say just call it done on
the edge and concentrate on center, and mask edge after coating mirror. I
guess I am stubborn, and want to get better results to the edge. Besides,
what would a mirror manufacturer do? Try to salvage it or start over or
what?

Rob in Ramona, CA

 

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