Re: ATM flexed mirror

["William Kelley" <wekelleylwk@sedona.net>]

Quite a lot of ATM'ers made center-bolt pulled spheres after my article in
Sky&Tel in 1992, and
when they were of modest size, and not too fast, they worked very well. Even
though your 1996
setup didn't quite reach 1/4 wave correction, with a good smooth sphere, it
probably performed
quite well.

Congratulations again on your latest foray into flex.  Regards- Bill


----- Original Message -----
From: Colin Caissie <optic@gwi.net>
To: <atm@shore.net>
Sent: Monday, August 06, 2001 1:30 PM
Subject: ATM flexed mirror


>
> Sorry about the bungled title to this thread (mime 1.0)
>
> I checked for astigmatism while doing the star test.  I use a laser
> pointer, bounced off a small polished bearing close to my 4mm orthoscopic
> eyepiece. The diode is small, for at 700x, I still see omly an airy disk.
> I did polish some lobes in one mirror  by using 3 discrete supports, TOT.
> It showed a distinct triangular star pattern.
>
> In 1996 I used a flex rig to correct a 10" f/6 I made.  The support was an
> o-ring set in a groove on the end of a slice of 8" pipe, pulled with a
> center bolt.  I am using an o-ring here, but since I want the correction
to
> span the whole diameter, I'm supporting at the edge.  Basically it's a
cake
> pan shape with the pan the size of the mirror +.030, attached to an
> aluminum plate, the pusher/cell.  The o-ring (McMaster-Carr O-ring stock
> 1/2" dia) and supplemental sponge rubber rings as mentioned in Mr. Adler's
> article stay snug against the perimeter ring.  I used his puller approach
> also, with 5/16" threaded rod through a 1/4" aluminum plate.
>
> The scope is a truss tube using single pieces of aluminum tube running
> through sheet metal enclosures.  I have access to a CNC turret punch , so
> sheet metal is the style of the day.  It is (or will be) a Dob mount,
> trying out the teflon sheet material mentioned in the recent S&T issue.
>
> I'm excited about the flex mirror, the auxiliary fan idea, the truss tube,
> and the slick teflon.  These are firsts for me, and I expect it to come
> together well for Stellafane.  Look for an industrial style unit.
>
> CSC
>
> P.S. Has anybody noticed that their telescope designs reflect their
current
> career?  When I was designing sawmill equipment, everything I made could
> withstand a butt log or skidder impact.
>
>
>