Main Mirror Cell Installation

I installed the VMC ("Versatile Mirror Cell", from 'Optical Supports' in Florida) into the 10" tube yesterday.

The VMC has 3 mount points separate 120 degrees from each other.

I calculate the separation between mount points:

C = 2*pi*R, where R = 5.0".

C / 3 = 266mm.

Then I created a tape segment exactly 266mm long and taped it to the tube and drilled the first hole. The I re-taped it again offsetting from the first hole and drilled the 2nd and 3rd holes. It came out VERY well. If you get very accurate 120 degree separation between the holes, the VMC is guaranteed (by design) to be located symmetrically in the tube.

I offset the VMC about .5" inward from the rear of the tube so as to allow for an end cap and possibly a 120mm fan to be installed at the back of the tube.

The end cap and calling a machinist is next.

Aluminum Tubes

I received my aluminum tubes from Hastings Irrigation, a few weeks ago. They seem very good--very round and sturdy. I ordered two tubes: first one is 48" of 10.0" O.D. for the main telescope, and the second is 12" of 12" O.D. tube for my novel saddle-mounting scheme.

The tubes were covered in oxide, inside and out. I used rubbing alcohol and a rough sponger to remove the oxide.

The 10" O.D. tube has a wall thickness of 0.064".

The 12" O.D. tube has a wall thickness of 0.090".