[ATM] Steel tubing for mirror cell

["Alan K. Henderson" <alankh@ev1.net>]

Here is my rough draft for the mirror cell. Image is to scale. (Upper portion not designed yet - saving the easiest part for last.)

http://users3.ev1.net/~alankh/CellDraft.gif

The design assumes 1" extrusion for the cell frame, 1/4" bolts for the triangles (not shown), 1/2" collimation bolts, and two lower support pins made from 1/2" bolts and 1.5" nylon cylinders (and 3.5" long). As you can see, I had already decided to separate the collimation bolts from the mirror support. My first concern about this design is whether 1" tubing is wide enough for drilling a half-inch hole without a structural integrity problem. I'm confident about the bolt thickness; K&B say they'll support a 30" mirror, which tends to weigh quite a bit more than 50 lbs.

My biggest concern is the lower mirror support. The pins must support 50 pounds. They are currently set 50 degrees apart from each other. The horizontal extrusion between the pins prevents the downward force of the mirror (when pointed at horizon) from pushing the pins away from each other. I doubt that the current design is sturdy enough, but there are several ways that they could be reinforced. There's room to add two extra support pins, but figuring out how to evenly balance the load between four pins would be difficult. 

Alan K. Henderson
_______________________________________________
ATM mailing list http://www.atmlist.net/