On 2010-06-17, Searcher7 wrote:
On Jun 17, 7:43*am, Jim Wilkins wrote:

[ ... ]

If you can pass the rod stock through the spindle you can machine a
part on the end with access to its entire length. Otherwise you have
to plan how to machine the area clamped within the collet or chuck
jaws in a second operation with less centering accuracy, or waste some
material, or hold it between centers. The difference is mostly
convenience and forethought.

[ ... ]

Yes, I just need to figure out the differences between MT3 and 3C
collets. And determine if it is plausible to expect to be able to pass
3/4" through the spindle under any circumstances.

Yes and no!

1) No -- with 3C collets.

2) No -- *no* diameter with MT3 collets.

3) Yes -- with a chuck on the spindle.

4) Yes -- with a 5C collet chuck on the spindle

5) Yes -- with an ER collet chuck which mounts to the spindle nose
instead of via the internal Morse taper of the spindle.

I may not bother getting collets that have more than a 3/4" capacity
for my lathe.

Unless you can mount them outside the spindle (e.g. the external
5C collet chuck, or an ER chuck which mounts properly to the spindle
nose. This is an argument for having both the 3C collets for smaller
work, and the external 5C collet chuck or the ER chuck if you can
find/make one to fit your spindle nose.

Enjoy,
DoN.

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