Originally Posted by
JackJohn
Thanks guys! Yes, I can make a chaser if the bb shell is not too damaged, as said I tested another bb cup and worked fine, hence my puzzling, if the the shell was damaged that wouldn’t have worked.
In the end, my aim is to understand if I can still use that Campy bb cup or if the risk of damaging the frame shell is high, from my experiment above it’s not clear, your answers are clearer on that
oneclick in point c) do you mean completely removing the damaged threads and have a flat surface instead? Will the cup have enough threads to hold tight?
If a damaged cup damages the shell threads it is likely to remove material. The good cup will still fit, but the fit will be looser.
I'd get rid of any thread sections that were bad, down to the thread roots - a part-circle of thread is worth keeping, though it may make initial alignment a bit tricky.
And likely yes, rule of thumb is that most of the load of a threaded fastener is taken by the first three threads.