On Jun 17, 10:21*pm, "DoN. Nichols" wrote:
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.

Yes. I'm on my way. :-)

Thanks a lot.

Darren Harris
Staten Island, New York.