I purchased a pre-wired Torchiere floor lamp that attaches together in sections of hollow iron rods that each have a smooth end and a threaded bolt on the other end. On one of the iron rods the thread on the bolt does not have a sharp edge - like the others - which is preventing the bolt from 'cutting' a thread into the connecting hollow iron rod end when I thread it into the opening. I was already issued a refund by seller who said to just "keep the lamp." My mom loves the lamp so, if possible, I want to try to salvage it. I tried turning it as far as it will turn and then taped a small plastic collar with foam around the rod to hold it in place. But the halo torchiere light makes it top heavy and it is not secure. Is there a collar or something I can use to secure the torchiere section to the lower iron rod since I'm unable to screw the 'threaded bolt" into the rod to tighten securely?
I solved this by using a pipe repair clamp from the plumbing department. It is meant to seal pinhole leaks in pipe. It looks like a 3-4" long bracket that clamps to the pipe --not in this case the floor lamp tubing-- and has a rubber, inner liner. Get one in the 1" or greater size. It has two parallel bolts that tighten to clamp it all together.
It's not the prettiest solution but it works. I salvaged a perfectly good floor lamp with bad threads this way.
You could try removing your tape, plastic collar and foam. Then carefully place a forming sleeve over the gap that spans between 270 degrees and 315 degrees of the circumference of the gap around the tubing post. This cover can be made from any one of a number of materials and if it is made long enough beyond the gap width you can use strong tape to hold it in place around the tubes.
If you use a paper or thin paperboard material (a manila file folder material would be ideal) use wide strips of clear plastic packing type tape to line the insides of this piece so that when it is taped in place the very smooth surface of the tape faces into the circumference of the gap area.
Now mix up a good sized batch of epoxy (I recommend to use the grey JB Weld) and stuff it down into the gap through the narrow opening of the wrapped forming material. The packing tape liner that I mentioned above will not bond to JB Weld and leave a very smooth surface on the cured epoxy.
After the JB weld has cured (approx 24 hours) you can remove the wrapped forming sleeve. A second application of epoxy can be applied to fill in the remaining area where the opening was in the forming sleeve. (I leave it to you to decide if you want to try to use more sleeve material to try to form the remaining epoxy after you fill the space or just gob it in and sand it down after it has cured).
If this is done correctly there should be a very secure connection without wobble in the joint.