Before painting can begin, the first step in tube repair is fixing major dents. The Milo refractor that I am working on now had major tube dents. Actually these were crush marks caused by the tube not being properly seated in the wood cradle in the wooden box. Looks like the lid was force closed or something fell on it. This fractured the 1/2" thick box top and crushed the tube. These dents were so bad that collimation of the scope was thrown off. I was able to buy the scope used, apparently because the previous owner, who bought it used, didn't have the time or ability to repair it.

While I had dealt with small tube nicks in the past, and had filled in drill holes; I wasn't sure just how to deal with this tube. Replacing it would be next to impossible, and I could not just simply fill in these major depressions in the tube as while that might be cosmetically ok, it did not address the fact that the tube damage had affected optical collimation. I contacted one of those auto body places that do body repair for things like hail damage. I was told that their process would not work on aluminum. Another possibility would be to fabricate a mandrill that had the same o.d. as the tube i.d. and to then force it thru the tube pushing the dents out in the process. This would require that the 2 glare stops be removed from the tube and then replaced exactly where they were. The danger also existed that the mandrill would get stuck in the tube and forcing it out would further damage the tube.

The best solution turned out to be use of a tail pipe expander. This is a device that is used to expand bent tail pipes. It basically works like a big molly bolt that is used to support weight on walls where pictures need to be hung where there is no backing stud to support the weight. Two opposing nuts which come together on a threaded shaft push up metal plates which are held in place with big o-rings. The tail pipe expander is closed at a diameter of about 2 inches or so and fully open at about 3.5 inches or so. This would be perfect for the Milo telescope tube. As the two areas with crush marks were on both ends of the tube were between the tube ends and the glare stops, they were accessible.

See the posted photo of the tail pipe expander.

Barry Simon