Thursday, April 9, 2009
Now for the rest of the mirror cell
Now that the tailgate has been finished, the next steps are building the flotation system that will support the primary mirror and making the side pins to keep it captive on the tailgate without chipping or worse yet, breakage. I cut 3-inch long sections of 1/2 and 3/4-inch dowels and hammered them into a wood block so I could drill a hole through them while keeping my fingers away from the drill bit. That turned out to be a more difficult proposition than I expected, and it took a number of tries before I got a set of side pins I was satisfied with. After drilling out the side pins, I sprayed them with flat black paint. Another task will be adding a pair of split bolts on on which a sling will be place to support the primary mirror when the telescope is pointed near the horizon.
Finding fully threaded bolts of the correct size is looking to be a chore, but they are a must for all the bolts that will be added to the tailgate. Because of the corrosive atmosphere here in my area, I want to use stainless steel bolts, washers, screws and nuts so they will look new even after years of observing. I would prefer to make the bars and triangles for the flotation system out of stainless steel, but the cost of stainless steel sheet metal and bar stock is bound to be at least several times that of ordinary mild steel. So I'm going to try to find 6061 series aluminum alloy plate and bar stock instead because it doesn't need painting and I can cut and shape it easily with the tools I now have. If that is not feasible, then I'll use mild steel and prime and paint it in the same manner as the tailgate.