[ATM] Re: Second Thoughts on Mirror Support

[djd521 at comcast.net (Don D'Egidio)]

Here's the one photo I have of the back of my Discovery 17.5" dob. The three RTV supports ( approx. 1.5" OD X .25") are placed in a triangular pattern around the location where the collimation screws (3/8"-24 threaded rod) meet the metal plate. The collimation screws end in heim joints bolted to the plate. You can just make at one at collimation screw #3. The original collimation screws where 1/2" carriage bolts, 4" long with a heavy spring and a wing nut. It was very difficult to obtain very small movements for precise collimation. The new system is as smooth as silk with no free play.

You can see that the metal plate has a triangular form and has an edge about .5" that is bent down at a 90. The apex of the plate has about  1.5" W X 2" H bent up at a 90 for edge support. The fan is a 5" 100 CFM 12VDC.

http://dvaa.org/ATM/Mirror_tailgate.jpg

Don