[ATM] homemade diagonal

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

Hi all,
After waiting for months for the ambient temperature to stabilize in the
70's, I finally finished polishing out my diagonal flats.  Fringe lines are
straight to within .125" of the edge.  One corner has a partial bullseye in
it.  The flat is 1" larger both ways than the finished diagonal will be so I
am not worried about the edge or the corner yet.  I hope to trepan it out
this weekend.  I have a piece of exhaust pipe 3.25" in inside diameter.  If
I can mount it so that it spins true on my drill press, I will be ready to
go.  The flat has been encased at a 45 degree angle in dental plaster for
four days. By Sunday night I will either have a diagonal large enough for my
16.5" telescope, or multiple pieces of broken glass.
My question.  Can I test the telescope with the primary and the secondary
uncoated?  With a 2.4" coated secondary the telescope tests great.  If
possible, I would like to get the secondary and the primary coated at the
same time.
I realize that this is probably not possible. If anyone has done this, let
me know.

BTW- When I test the secondary flat, if I place it on its matched mate, the
fringe lines are as stated and VERY close together. If I press on any part
of the secondary, the lines spread apart and warp around the pressure point.
I assume this is normal from what I read in other recent posts.
Clear skies, Jerry

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