"Bob La Londe" wrote in message
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"Jim Wilkins" wrote in message news
"Bob La Londe" wrote in message
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I need to machine some metric trapezoidal threads. Both internal
and external.

What's the best way to do that?

Is hand grinding the tools going to be my best approach? I think
maybe it is since they are for making molds of two mating parts.
The molds can't be of the exact thread forms or the parts won't fit
together. A proper cutting tool for those threads might not
produce what I need. I'm still thinking my way through the
process.

A local vendor who has closed sold me an imported 3-axis angle vise
like this that I use to surface-grind angular and trapezoidal
threading and spline milling bits.

http://www.wikiwand.com/en/Tool_and_cutter_grinder

*****************

The link brings up a CNC tool grinder. If that's what he gave
you.... WOW! I'm impressed.

You reminded my I have an antique (its so old the cords have cloth
wrap) basic tool grinder on the shelf that I saved from going into
the dumpster on a house clean out from a hoarder who passed on.
Its halfway apart and needs to be taken all the way apart, but it
might just be a good project to move up the projects board.

I wish! My surface and cutter grinder is a small manual machine from
the 1940's.

The vise is similar to the vise on multiple swivels on the table of
the green manual tool & cutter grinder. I used it for example to grind
a trapezoidal bit to spline a shaft to accept a motorcycle final drive
sprocket, in the transmission on my sawmill.

I machined the shaft grooves slightly too small and pressed on the
sprocket, so the bit geometry didn't have to match exactly.