Tool to chase spark plug threads from the inside out.
I tried inserting it all the way into the piston, past the threads completely and then expanding the head. However, I could not get the tool to engage the spark plug threads when backing it out. Plan B was to insert it only deep enough to expand into the last few good threads and past the part I cross threaded.
That worked fine, but because its fluted without any support like a regular tap any resistance seems to bend the tool. It did a good job and now I can screw in the spark plug without paying attention and get it straight.
Because of the bending the tool seems only good for a couple of uses unless there are only minimal issues with the spark plug thread. Perhaps the larger tools are stronger, this was a 10x1mm tap.
