"Larry Jaques" wrote in message
...
On Wed, 18 Dec 2013 13:08:16 -0500, "Jim Wilkins"
wrote:

"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 though R8 was the winner there, from previous conversations. Easy
availability and low cost, etc.

Work-holding collets like 5C have large holes through the center and
tubular drawbars or clamping nuts. Tool-holding R8 and Morse collets
take a small-diameter solid drawbar and hold only short objects like
endmills.

Exceptions such as the 5C endmill grinding fixture
https://www.penntoolco.com/catalog/p...ategoryID=3983
and Morse collets in a rotary table make their limitations when
swapped quite obvious.

The dialog in one of those links mentioned parallelism. I thought
collets were also designed to remain parallel internally since
they're
designed for holding round objects. Am I missing some knowledge
here,
or what, teacher?

5C collets have a small gripping range of only a few thousandths above
and below their nominal size. That's not a problem for holding
accurately ground drill rod, but they may not fit hardware-store round
stock or bolt shanks as well.

jsw