Re: ATM Main mirror cell design - need help with bearings

[Ross Sackett <rsackett00@yahoo.com>]

Tom:

Since we're all sharing our bearing solutions, here's
mine.  For my triangles I use a stainless OPEN-ENDED
acorn nut (McMaster-Carr 94301A105 thru -A160) riding
in a conical depression made with a single-flute
countersink (less chatter in the aluminum triangle =
smoother bearing surface).  A 6-32 panhead machine
screw passes through the triangle and nut into a
threaded hole in the bar.  This is locked from behind
the bar with a small nut or a dab of Loctite.

To make 1 d.f. joint for the bar on the collimation
bolt I bend a fender washer to make a gentle ridge,
and J-B Weld it to the bar (with the ridge transverse
to the long axis of the bar).  This rides on a
self-locking flange nut threaded on the collimation
bolt.  The bolt passes up through the washer-bar
assembly, which is held loosely captive by two jam
nuts cranked together.  The bar rocks neatly on the
flange nut with little side-to-side wobble.

This sounds complicated, but it is a cinch for anyone
raised with an erector set.

Ross




            


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