[boydage]

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?

[pippin88]

What bit? Single tooth? 3 tooth? Full thread?

Single tooth can cut multiple pitch
Multi-tooth can only cut a single pitch

Bit like lathe bits - there are full form large threading inserts - they only cut the designated thread, but form the full thread profile.
The inserts you have and use for multiple threads are partial profile - they don't cut the top of the crest.

[Superman]

Your train of thought is correct ... threadmills are specific to the thread pitch, not the thread diameter so a cutter that would cut a M10x1.0p can be used on M22x1.0p
Now, me also saving $$$, and inventory, have used a single point internal lathe threading tool to threadmill a thread (internal or external)
I have also on hand a three flute 60° vee tool (similar to a circlip/grooving tool) https://www.sandvik.coromant.com/en-...s/coromill-327

Initial cost is high, but your options are expanded.

[boydage]

Hi. Sorry yes, a single tooth which is why I couldnt understand why they advertise the range like that. I would be tempted to use an M10 single tooth milling bit over the M18 single tooth, twice the price for an endmill that is just larger. The single tooth is barely going to need a big shaft in my mind.

Ive just bored out a 17mm hole 30mm deep in a piece of brass, so I can machine that (never done before). So I will be wanting to mill an internal RH and in the opposite component a LH thread into the bore. Thanks for answering my question and confirming. I was hoping to bore the correct size so I dont need to worry about the crest.

[pippin88]

Single tooth thread mill can be used for a range of pitches

Yes, bore diameter needs to be correct

[John-cbn]

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