Originally Posted by
CyclingFool95
Does M4.5 have the same pitch as M5? If not, when you try to drill and tap M5 where the M4.5 hole is, you will probably end up with a mess - there's not enough difference that the drill will clean out the M4.5 threads completely. If they are both coarse thread they are both .5mm pitch.
Measure.. there are thread pitch gages , which are part of most machinists tool boxes...
Metric pitch is thread per MM , so count how many per 10mm then divide by 10 .