"Larry Jaques" wrote in message
...
On Wed, 18 Dec 2013 09:05:32 -0500, "Jim Wilkins"
wrote:

I can see the potential benefit of odd thread pitches, but what is
the
benefit of a 5C over other collet tapers?


Lower price and versatility. You can buy several types of milling
fixture that take 5C collets:
http://www.amazon.com/5C-CB-5C-Colle.../dp/B0007Q1Q50

I have 3-jaw and 4-jaw chucks with 5C shanks that let me move a part
between the lathe and mill without losing zero position.

Another option:
http://littlemachineshop.com/product...ProductID=2532
http://bbs.homeshopmachinist.net/thr...-vs-5C-collets

ER collets have a wider gripping range, but 5C collets match the
diameters of fractional-sized rod stock and bearings.

If cost is more important than capability to you, a 4-jaw chuck can
hold almost anything. I like collets for small delicate parts because
I can get in close to watch without having big spinning chuck jaws
near my head and hands. The last thing I made was a small brass test
probe pin that plugs into my truck's wiring connectors without
expanding them. It deflected enough that I couldn't turn it parallel
so I had to file it to final size, very close to the collet.
jsw