[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
[ATM] First mirror help
After reviewing the archives, much material on the web, and sleeping with
Berry's book, I think I am making progress.
Background. First mirror. 6", 3/4" thick plate glass blank targeted for
F8, ended up F7.5. Using slitless moving source Ronchi tester, don't have
dial indicator mounted yet for offsets on Ronchi or Focault. Ronchi using
100LPI screen printed on laser from Stellafane pattern. ROC is about 88",
all Ronchi images are inside ROC.
The problem: with multiple figuring errors, which do I try to correct first?
Based on the Ronchi test images near the end of the link below, I think I
have a TDE and a center flatter than it should be ( a hill?).
<http://members.cland.net/ksclement/emptynest/atm_mirror.htm>http://members.cland.net/ksclement/emptynest/atm_mirror.htm
Based on several resources including the archives of this list, I have
tried several methods for reducing the TDE and hill in the center, with
fairly poor results. I tried tangent strokes MOT to attempt to lessen the
TDE, which seemed to worsen the TDE. Based on some posts by Bob May and
others I did 30 minutes last night, MOT, with 1/4 W strokes and hands at 12
and 6 on the mirror at about the 1/3 radius so that I was not tending to
push over the edge of the lap.
I think I made progress using that combination, which leads to the questions:
When you have multiple problems, which one do you go after first?
Am I correct in my analysis of the Ronchi images as TDE with a hill in the
center?
Will the short W stroke keep me headed in the the direction of a sphere?
Thanks,
Kurt
Nixa, MO
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.596 / Virus Database: 379 - Release Date: 2/25/04
_______________________________________________
ATM mailing list http://www.atmlist.net/