I have the aluminum rails, and I have started putting them together. The only difficult part of the process is getting them exactly parallel to the optical axis of the telescope. Here you can see me using a square to make sure that the rail is exactly perpendicular to the tube. I suspect that if geometry class had required me to prove some of these problems, I might have been a bit more interested! (I feel so sorry for my geometry teacher!)
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I hold the square tube in position with a couple of hand clamps, and then drill through the holes in the square tube to mark where the holes go in the cylindrical tubes.
It turns out that the 1 1/2" long black oxide bolts I bought at Industrial Hardware on Thursday aren't tap bolts (the kind where the threads go all the way to the head). Therefore they are too short, so I'm using some shiny 1 1/2" hex head tap bolts as a placeholder.
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Industrial Hardware, unfortunately, is like a computer: they sell me what I ask for, instead of what I need. They seem to be deficient in their ability to read my mind in the future, but that's okay, they are very nice people, and they seem to have everything I can imagine.
Here we have the first rail attached.
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The holes in the cylindrical tubes are tapped 1/4"-20. I had originally drilled the holes in the square aluminum tubes at 1/4" on the drill press. While these holes were pretty accurately marked, they weren't quite accurate enough to get the bolts to slide in without a struggle, so I went up two drill sizes.
Tomorrow after church I'll try and get the other two square tubes attached. I had wondered how I was going to get these square tubes attached exactly at 120 degree angles, but it turns out that the holes in the cylindrical tubes were measured pretty carefully, so if I get one of these holes flat on the floor, I just have put the square tube exactly at the top of the tube to be in position.
I'm afraid that I am going to have to do some more paint work on the exterior of the tubes once I am done--the paint has gotten a bit scratched as I been drilling holes.
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