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What I see as the problem with the razor blade idea is that it is
dependent on the shape of the tip of the tool cutting the thread. Any
wear and you are getting off in diameter. And if you were cutting a ASME
thread rather than a sharp Vee thread you would have another difference
to contend with. I believe that there are thread wire sets that hold onto
the calipers for easy measurment of the most critical dimension. However
if you can cut one to fit and measure it in a consistant way then
subsequent ones should trach that measurment.

Bill in Boulder "Engineering as an Art Form!"

For external threads, Fowler (IIRC), makes a micrometer attachment
consisting of 2 triangular prisms with little elastic thingies that
hold them to the micrometer spindle & anvil. Each prism has 3
different sized flatted points, so they'll fit a wide thread range.
The set comes with a set of tables to convert measured size to
equivalent thread dimensions. They work best with a non-rotating
spindle micrometer.
There also used to be a single triangular prism, again with
different sized flatted points, that SPI made. It didn't mount to
the micrometer - it has a little wire handle.
Owning both of these gems, I usually go for the wires & lump of
modeling clay!

Roy

--- In 7x12minilathe@..., "mikeaita1" <aita1@a...> wrote:

--- In 7x12minilathe@..., "Richard Albers"
<rralbers@j...> wrote:

--- In 7x12minilathe@..., "mikeaita1" <aita1@a...>

wrote:

thanks everyone for helping
i finally cut some respectable threads today
mike aita

Congrats! I know how elated I felt when I first cut something

that

looked as good as "the pictures in the book". :-)

Of course, you realize that few items really need the precision

of

single-point cut threads (few of mine, at least). I just cut

threads

that way because I CAN!

Do you have any unthreaded round stock left? ;-)

RA

Actually I cut 9/16 12 coarse threads for a fixture i need for an
invention i am working on. the coarse threads are very forgiving.
A remaining issue is knowing when the threads are deep enough.
Taking the tailstock off to try the nut is NOT the way to go,
although with a coarse thread I found I could realign the setup.
Putting the fine edge of a caliper in the threads seemed to work

for

coarse threads.
Seems like some simple attachments to the caliper could be made to
work for fine threads and even internal threads. Is such a thing
offered for sale or do I need to make it?
Thanks again for your help.
mike