On my lathe I have one insert for a 60deg thread, or 55deg, and external/internal. So 4 inserts have covered me for all. These are ok to use no matter what thread and what pitch is required.
I am looking at using my router to internally tap a thread a M18 x 1mm pitch into a brass hex. I am a little confused about the end mills available being named as M2 through to M22 all in different sizes and expense. I cant seem to understand why they are different? Angle is the same, is it because you are to set this to one op only?
I guess I would just buy the M18 1mm pitch endmill but its $100 so yeh, being a tightarse and asking before I buy something I might not need. Ie I cant work out why I wouldnt just use a M10 1mm pitch endmill and fusion 360 takes care of the rest.
Can someone shed the appropriate light on this please?