To answer your question Jtrav, No, not
anyone can help, but there are a few who can.
I use KBC Tools quite a bit for general tool supply
Toll free Phone (this number works from Canada, anyways):
1-888-522-8665
Page 298 of the current 2003/2004 catalogue.
If you want a replaceable insert type thread mill, there is a good selection of several Vardex thread mill toolholders available.
What would work would be KBC catalogue number
1-289R-220 ($300.80 canadian)
but, the actual Vardex cutter model number is
TMC-100-5
which is 1-inch shank dia, 4.38" overall length, 2.03" working length.
Insert for internal 1.5mm thread pitch is KBC catalogue number
1-2895-230
($82.07 Canadian)
This insert has a cutting edge is about 25.5 mm long, which will give you about 16 or 17 threads per pass.
Write yourself an incremental sub-program to make your milling cycle portable. Just move to the center of the hole for the start (and end positions) and then call the sub. Try to design a spiral lead in to the full depth cut, rather than a radial plunge.
Orbit, then retract to the center, move down an amount equal to some multiple of the thread pitch and cut the bottom half of the threaded hole, since your thread is longer than the insert is.
I found it works best to start low and spiral coming up (one thread pitch per orbit) while cutting. This keeps the cutter in climb mill mode for RH threads.
The feedrate that you would use would likely be .001" to .003" per cutter tooth per revolution, which would be a grand total of one tooth if using an insert threadmill. Just obey the normal speed limits for carbide in the base metal you are using. Use a good air blast to get the chips out of the hole, as you don't want them getting recut by the delicate points of the thread insert. Recutting a chip is like cranking your feedrate up to 200%.
Practise in a piece of MDF first
