Re: collets

Lew,

Well, here's how I've made collets:

1. Chuck up a bar of "stressproof" steel. This is steel that has an
artificially high yield point so that it bends a little farther
without taking a "set". Threads and finishes well as a bonus.

2. Do the ID clearance bore first, then turn the OD and seating
taper, then thread and part off. Leave a solid plug where the
gripping surface will be.

3. Re-chuck, zero it out, and bore to the basic size +.005 or so,
then generate the nose taper.

4. Cut the slots with a slitting saw on a regular mill. It's
typically easier to cut 4 slots than 3 if you don't have a dividing
head, and works just as well.

It's fine to just copy the socket seating angle on the collet in
most cases. Some folks like to add an extra degree or two there, but
IMHO that's not worth the effort as it really doesn't change much at
clamp-up.

Yours,
Dave Kowalczyk
TurboCNC software at --> http://www.dakeng.com

--- In CAD_CAM_EDM_DRO@y..., "LEW BEST" <bcl@c...> wrote:
> Hi All
>
> Sorry to post this to so many lists, I know some of you are on
multiple
> lists and this will get repetitious.
>
> I need to try to make a collet. The design is like a 5C with
external
> threads but much smaller. An R8 is only slightly larger in outside
diameter
> (I thought I might be able to turn down and externally thread an
R8, would
> also need to slightly flatten the nose taper. However after
reading the
> specs in the Mcmaster catalog I feel they are probably too hard
steel to
> turn.
>
> The collet I need is for a Black Diamond 31 drill grinder, is the
large
> collet that holds the larger bushings and the 3/4" bit for
sharpening. BD
> wants $120 some-odd for the one collet so I'd like to try to turn
one
> myself.
>
> All it does is hold the bit in place for sharpening it, no high
torque as in
> milling, drilling, etc. I'd appreciate any suggestions as to
material to
> use, how to cut the 3 thin slots on the face that allow it to
tighten, etc.
> BTW my eq is all manual, even though the CAD CAM group is included
in the
> list. I get good info from all the lists!
>
> Thanks
>
> Lew