The Tube Assembly Problem

The Tube Assembly Problem

It turns out that while I can use a clamp to get the tube assemblies properly round, once I remove the clamps, it returns to out of round. The only real solution is to reduce the diameter of the base plate of the mirror cell. I don't have a lathe capable of turning a 20" diameter round, but the solution is to sand the edge of the base plate.

I have a small belt sander that includes a rotating round disc. I have found that holding the base plate up to the disc, maintaining a steady pressure against the disc, and carefully turning the base plate, I can remove a very consistent, even amount from the edge. So far, have taken about 1/4" off the diameter without too much effort. I need to take a little bit more to get the base plate to slip easily into the tube--then I can put the mirror cell back together, and move forward.

Once I bolt the mirror cell flanges to the inside of the tube, it will pull the tube back into round (or at least close enough to round).