I’m having trouble with another thread. I’ve used a better quality steel, threading at 305rpm now, got a nice thread. I am trying to thread, M20 x 2.5mm pitch. My OD started at 20.06. My OD is now 19.88 and my threads are the full depth of the 2.5mm insert. I still can’t get a nut on? Any ideas?
I would advice investing in thread wires they are the only method i know of for proper sizing of threads.
I took another two almost spring passes and the nut winds right on now some sort of thread measuring gear is definitely needed.
I measure all of my external threads, takes seconds, easy thanks to DrAl's calculator, here, www.cgtk.co.uk/metalwork/calculators/screwmeasurement Measure the OD before starting. Choose a suitable drill bit from the calculator wire size. Deburr the part and measure with your drill/peice of mig wire. Subtract the original radius and double the result. That is the easy way to do it. Youd be looking for 20.3mm with a single 1.5mm drill bit/wire Internal threads I have not worked out yet. It should be easy enough to turn pitch specific tips for a bore gauge.