 Before cutting your tube in half, draw a few lines with a "Sharpie" pen so that you can re-align the tube back to it's original rotational position.
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 I used 8-32 threaded T-nuts glued into place to secure the removable half to the sleeve. The sleeve is glued and screwed into the half with the primary mirror and is not intended to be removable. The T-nuts in both the permanent and the removable half were "match drilled" to insure perfect alignment.
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 I forgot that old axiom; "measure twice, cut once". When you cut out a section of your sleeve to decrease the diameter, glue the ends together for strength. You can see where I miscalculated and needed to add a piece back in.
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 On the removable half, I drilled out the T-nuts to remove the 8-32 threads. They are now a tight clearance hole and the T-nut is acting as a bushing to prevent the cardboard Sonotube from wearing and enlarging the hole every time the screws are inserted.
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| I'm happy to report that the sleeve is accurate and repeatable enough to allow the two halves to be reassembled without need for recollimation. But since I was unsure of how well the two mirrors would remain in collimation, I also built a laser collimator. I've used the laser to check after every reassembly of the two halves and the mirrors are always aligned!
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 I made my laser collimator from a cheapo laser pointer and some Delrin bar stock. The Delrin is drilled with an oversized hole to allow the pointer to be calibrated. The pointer must shoot the laser parallel to the body and the body should fit snugly into the eye piece hole. Each of the X & Y adjustment screw also has another screw on the opposite side. By turning each of them, you can calibrate the pointer left/right and up/down. To calibrate, I turned on the laser, chucked the Delrin body in a lathe and turned it on at a very low rpm. The laser shot through the headstock of the lathe and scribed a circle on the wall behind the head of the lathe. I made an adjustment using the X & Y axis adjustment screws and repeated until the scribed laser mark on the wall was only a spinning point. This meant the laser beam was now parallel with the body. I would recommend that you do not use white or "natural" colored Delrin. Choose a dark colored material because the laser will need to bounce back into the originating hole at the end of the collimator body. The light colored material is difficult to see. Next time I make one, I would also mount the laser much further into the body. My current one is too long, tends to get banged around and is more prone to damage. Mine sticks out from the Delrin body because I wanted the On/Off switch easily accessible from the outside. Next time, I would figure out another way to activate the laser and have it recessed more for better protection.
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 After discovering the problem with using a light colored material, I stuck some 3M reflective tape on the end and easily solved the problem. Cheap laser pointers tend to project a rectangular mark. I drilled a .020" hole exit hole at the end of the collimator body and the tiny hole becomes a mask and a round laser mark is projected. It also helps to keep the point smaller after 12 feet of projection distance (6 feet to the primary and 6 feet back to the eye piece).
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 Here's a shot of the collimator inserted and turned on. You can see the red dot in the center of the primary mirror.
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| Here are some pictures of my machined spider for the secondary mirror and machined tailgate assembly.
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 The spider arms are made from 2024 Aluminum and the mirror mount is made of 6061 Aluminum. It is completely adjustable for collimation.
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 The tailgate is also made from 6061 Aluminum. In this picture, you can see the 3 collimation adjusting bolts and jam nuts. The slots and pockets you see are there only to reduce weight.
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 The 4 hold down clamps "float" on the screws and the springs apply a little pressure on the clamps and thus keeps the mirror in contact with the adjusting bolts seen in the photo above. These four clamps also help keep the mirrors in alignment. I've been told the clamps and springs are producing a distortion to my precisely ground mirror. While this may be true, I believe the flexing to be very slight and any distortion created to be minor in comparison to any other errors I may have ground into the mirror.
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