Repair Screw Threads

[composites]

Does anybody have advice for getting a nut back on a screw (22mm) that had a hammer taken to the end of it? The damaged threads are 2 1/2 full turns.

[parttime]

I would use a thread restoring kit like one from SnapOn. I have this kit and it has some thread restoring files in it. You could also use a triangle shaped file to try to straighten the bent threads. I would surely use a thread chaser, not a tap or die on this one.

[HuFlungDung]

If the screw is soft, it is possible that the thread pitch has changed (imperceptibly) for some distance beyond the obvious damage.

I would probably fix it on the lathe. But with hand tools, I would first file the OD of the damaged area so that it is the same as original. Then using a thread file, I would work back, start with the file teeth engaged in the good threads and slowly working into the damaged threads, and keep filing and rotating the part until the tool comes off the free end of the threads.

BTW, a proper thread file is a double ended square file, with different pitches of teeth cut to match a particular thread. There are three commonly available files, one for fine, coarse and metric pitch threads. There are 8 different pitches cut on each file.

If the damage is severe, you might as well just grind the damaged threads off to the root diameter as no filing operation is going to add metal to the threads, so you will end up with next to nothing for threads even if you do spend an hour filing away at them.

[composites]

I'll see about getting a file mentioned above today. Thank ya.