Hummm, I had not considered a tap or die to cause damage to a fastener. I just thought the fastener was "beyond" salvage. I have found a little trick that minimizes the damage..if you are still interested. Use a bit of wheel bearing grease in the flutes of the tap or die. It seems to pull the chips, rust and crud out if the way. Helps with galled threads as well. I have used the "thread chasers" that look like a file for minor damage control. You can cause all kinds of havoc if you use the wrong thread pitch for sure. Still have some fasteners that will not clean up even after the tap and die treatment. Most were deformed or bent just a bit and were beyond saving.
