ORIGINAL: Campgems
ORIGINAL: Ken6PPC
ORIGINAL: lnewqban
It could be that the thread on the shaft is slightly damaged, so the 1/4'' nuts don't fit all the way.
Wish you luck!
That would be my guess too! If so, before you buy a new crankshaft, try running a 1/4''-28 die over the threads. That might be enough to clean it up so that you can still use it.
NO No NO. Trying to chase the thread with a die will only result in screwing up the remaining threads. If it isn't 1/4-28 as suspected running a die along it will absolutley ruin the crank. Even if it is 1/4-28, and the treads on the end are damaged, trying to chase the threads will most likely result in the die establishing a different thread pattern. If the nut cant screw on, the die won't eaither an will make its own path.
A close inspection will tell if the thread is damaged. If they are, a simple file is the best tool to use, Hold it at 30 degrees to the shaft, the same angle as the threads and file pushing the file to the center line of the shaft. Don't even do this though unless you can see that the threads are damaged. I doubt that they are as
rsieminski sates that a nut will screw on three turns prior to binding. That indicates the start of the threads are good and what he is seeing is an example of thread pitch being different. As pointed out eariller, the 1mm pitch and the 28tpi are very close and it would take just about three turns to take up the normal thread clearance.
Don't fix something if it isn't broke.
Don
Don, he said the nut will thread on the crank, and then get tight. That means the first threads are fine, and the threads further up the crankshaft are the ones that are buggered up. A die will clean this up better than ANY file!
Unless of course, you think one can cut threads with a file better than machine tools can! [sm=75_75.gif]
Edited to add:
Don, I agree that a triangular file COULD be used to clean up the crankshaft threads, if it was used by someone who understood how threads are cut, and how they are supposed to look. Since the OP obviously doesn't posess those skills or knowledge (he doesn't have a thread pitch gauge, and didn't even know what thread pitch really was), do you REALLY think he will instinctively know how a thread is supposed to be cut (or this case, FILED)?
I think he is much better served to use a proper thread die to clean up his crankshaft. Actually, he would be BEST served by taking it to someone who understands threads and how they are measured and cut.
(No offense intended to the OP. He is trying to learn, and there is NOTHING wrong with that!)
Anyway, that is my opinion, and you are entitled to disagree!
