On Fri, 31 Jul 2015 09:16:46 -0500, Pete Keillor
wrote:

On Fri, 31 Jul 2015 07:58:08 -0400, "Jim Wilkins"
wrote:

"Pete Keillor" wrote in message
news
...........
I bought a two piece pot collet for finish the cap, I was getting
frustrated trying to chuck the mostly finished cap in the four jaw.
But now the collet body won't thread into my homemade draw tube,
although it will into the ones for the Hardinge mill. I'm going to
have to open up the threads on the homemade one a little, which I
hate
(re-registering the threading tool on an internal thread). Oh well,
if I mess up, I have the stock for another.

After that, it's paint it and run. Oh, and make a couple files.

Pete Keillor

You may find re-registering the bit in the internal thread easier if
you set the compound parallel to the ways so your X and Y adjustments
don't interact. 29 degree infeed isn't as necessary for light cuts,
and you can imitate it by feeding both.

I bottom the bit in the groove visually and then take up X slack while
turning the spindle by hand until the bit starts to shave a chip. It's
easy on a back-geared belt drive South Bend.

-jsw

Good tip, thanks. I'll report how it works.

Pete Keillor
In case you haven't tried picking up the thread yet another thing that
works for me is to do as Jim suggested with the compound but I like to
try bottoming the tool in the groove by moving the coumpound a little
in either direction (taking up backlash of course!) until I find the
bottom of the thread. Set the X axis dial to zero at this point. Then
use Jim's method of slowly turning the work while slowly advancing the
tool in X and seeing which side of the thread the tool picks up and
how far from the bottom of the thread you are when the tool just
starts to cut. Looking at the X axis dial you will be able to see how
far from zero you are and can then move the compound in Z the correct
amount to allow the tool to bottom.
Eric
Eric