Re: [ATM] ?Glued Mirror Cell

[Thomas A Simmons <tasimmons@raytheon.com>]

Hi Jan and Rod,

  Richard told me NEVER to reveal his magic, but since you let the
cat out of the bag, it was his patent and a few off list messages
that inspired this cell. I didn't follow his recipe on the collimation
bolt, as the off-the-shelf screw didn't require soldering and all that.
Simplicity at it's finest!

  You asked

"Do I understand that you made the collimation bolt - bar
pivot point by basically countersinking the mirror side of the hole
through the bar, and RTV'ing the ? flathead machine screw into the
hole by gluing the screwhead into the countersink?"

Yep. I don't remember the screw type, but it was a 5/16 screw with a
3/4 inch or so flat top and perhaps a 135 degree champher underneath.

You then wrote
"Seems like you could back it up by putting a locknut on the
underside of the bar spaced a little way back, and glued to the bar
as well."

Weeeellll, this is un-necessary. In sequence from the bar I have a flat
washer, followed by a spring, another flat washer, the bottom of the
mirror box, a nylon washer and then a wing nut. The spring came from
MSC and is rated for ~30 lbs. The first springs I used were too soft,
and allowed the mirror to shift somewhat. The nylon washer under the
wingnut allows very smooth adjustments with low resistance.

I believe you mentioned Tom Kracji's web page, which goes in debth into
Richards patent and cell design. All I can tell you is that it works
very well with this 25 pound mirror.  Maybe $5 in parts?

Another tip. I believe Mark Holm is the author of "Cell Parts". I used
this program to print out paper templates, thus simplifying the task
of assuring the three bars were identical and the holes were properly
positioned. (Ellen was mentioning something along this line the other day)
With a little creativity, you can also set the Foucault reduction programs
to print out a mask that will have the proper radii for the attachment
points-set the mask opening to be VERY wide and VERY narrow.

I'll try to pull the mirror out of the scope this weekend and snap a
picture of the back of the mirror showing the cell.

Tom
Tucson, AZ

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