Re: [ATM] figure stroke ten inch

["Mitchell R" <funnybone101@embarqmail.com>]

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Tom Fredrickson
Sent: Friday, September 28, 2007 10:05 PM
To: atm@atmlist.net
Subject: [ATM] figure stroke ten inch

Hi all,

I'm working on a 10 inch mirror full size lap. I turned the edge and
went to work with short coc strokes to clean it up. Now I need to add
correction to the edge. I have been working the edge and it is going
the wrong way. I feel I need to work the center and make it deeper.

Here are my numbers in millimeters roc 2712 mm Moving source mirror D
253.5 mm
mask zones 
1	0	56.684
2	56.84	80.164
3	80.164	98.18
4	98.18	113.37
5	113.37	126.75

Readings 0, 0.49, 0.84, 0.98, 0.98 

I appreciate any help.

--
Tom

I'm working on a 10" as well (F/4.9) with a full sized tool. I got close on
my first figuring attempt but Zone 3 ended up over, and as in your case as
well the edge was too high. I find it difficult to add edge correction. Even
with a narrower, long stroke concentrating on the edge. Usually I have had
the best success (accidentally) by overshooting on correction then
sphereizing and some of the edge correction remains behind for the next
figuring attempt which is usually better. I have to figure out why a
sphereizing stroke on a parabola seems to add edge correction for me, but
when spherical a mirror will just stay spherical. Don't know, but then again
figuring will always find some new way to confuse you a bit. I don't think a
sub-diameter tool is necessary. It could be beneficial in some situations,
but a full size tool can be used without too much difficulty. For someone
like me who has pretty much only used full sized tools it help to keep
things less confusing. 

Good Luck!

Mitch
 


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