On Sat, 24 Jul 2010 22:24:45 -0500, "Greg O"
wrote:


"Ignoramus8473" wrote in message
m...
OK, so I have a CNC mill, in which I know the spindle speed only
approximately.

Can I, realistically, use it for threading through holes, perhaps with
tapping head?

i

The tapping head is one option.
We used some tapping attachment years ago, I forget what they were, but just
a tool holder with some slip joint in it. Run the feed slightly under the
calculated feed/speed rate, and reverse the spindle and back out the feed at
teh same time. Not sure if it would work in your situation. My bet is you
will be able to find a Tapmatic head cheap enough with your scrounging
abilities.
Greg

Floating tapping "attachments" can be made very easily now that he has
the mill.

Simply machine a slot down a couple inches down the side of a piece of
1" bar, except for the last 3/8" inch, drill a 9/16" hole in the end and
a couple inches into the bar..matching the length of the slot..and
insert a 9/16 bar into the hole. Drill and tap for a socket head cap
screw..and you now have a sliding bar inside a tool holder. Now you can
make up a bunch of similar 9/16 bars..all with the proper hole and a set
screw for each size tap you are going to be using over time.

Id hook a spring to the socket head cap screw and to the 1" body..and
voila...you have a floating, spring loaded tap holder.

Feed in at 75% of your tap lead and the tap will go in, pulling itself
down the slot a smidge faster than your spindle feed rate, and when you
reverse..and pull out..it comes out of the hole faster than you are
retracting. Voila!

Same thing works just hunky dory on lathes as well. I made up a few of
them that I can stick in the mill or the lathe.

I made mine with 3/4 body and 1/2" tap holder rods.. shrug


Its a good first project. If you have a collet tap holder..simply make
the body big enough to hold your collet bar and drill and tap a hole in
the collet tap holder to run in the slot.

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch