Nuts and bolts

If you have only a bolt too long you can easily make spacers by stacking washers on the long bolt and run down a nut to compress the washers. Than run 2 layers of electric tape around the stack to make it easy to handle. After this you can remove the nut if you need to.

If a thread on a bolt is damaged and you don't have the right die set to recut it you may do with an homemade thread chaser. Get an old nut the same size the thread has and cut 2 slots with a hacksaw in it's thread. The idea by this is to cut the threads with the nut, the slots being for the metal you shave off. Coat the nut prior to use with either cutting oil or white grease.

You may have to discard the nut, maybe even the bolt you tried to rescue but it's worth a shot. On most threads that aren't too damaged this works just fine