Why 1.045" diameter?
If the viewer chooses to cut the internal thread using a basic single point tool
this will produce a thread without a radius on its tips which will then foul with
the root of its mating thread. When using this form of cutter the internal bore must
always be larger than the theoretical value so as to avoid the problem. Similarly,
with an external thread the outer diameter should be undersize to prevent a similar
situation. The bore diameter given therefor produces a thread depth of 75% a situation
that only very slightly reduces the strength of the joint made.
For me, making the thread with a tap, the tips of the thread produced would have
the designed radius on their tips. However, as there is very little reduction in
strength, it speeds up the process as there is less depth to cut. As cutting an internal
thread is a slow process reducing the number of passes that the cutter has to make
is very worthwhile and would suggest that whatever method of producing the thread
you decide to use that for internal threads a depth of between 65 and 75% should
be the norm.
Ready for the next stage
With the parallel portion and the thread now complete the workpiece can at last be
tested against the mandrel nose that should be, if the above process has been worked
to, just a formality. You will now be ready to proceed with whatever it is you are
attaching to the mandrel, chuck backplate, faceplate or collet chuck, the accuracy
of which will benefit from the attention to detail taken in the initial stages of