collet question

[decoy91288]

I have noted eBay auction descriptions of collets as being internally threaded or not. Guess while I am asking I should ask for a definitive statement as to 5C, 8C, etc. I have looked at some manufacturer and catalogue descriptions and think I know the differences but do not want to learn otherwise after buying.

------------------
Craig

[MikeHenry]

As I understand it, 5C collets with an internal thread can take a stop to position the workpiece so that it protrudes a known distance from the spindle. The stop screws into the internal threads on the collet and usually has a rod of some sort that is adjustable for length.

Mike, near Chciago

[Uncle Dunc]

If I understand your question correctly, knowing that the collet is 5C wouldn't be enough. Apparently some 5C collets are internally threaded and some aren't. You'd have to ask about that feature specifically.

[decoy91288]

thanks for the information. I was not very specific due to not knowing enough to even ask an intelligent question. What I need it a primer on collets in general it seems.

The appearance of the "internally threaded" collets is not different in any way that I can see in pictures. Maybe that is why they call them "internally" threaded.

Did I understand that internally threaded has an additional part (the stop) to deal with??

[Thrud]

The internal thread at the rear end of the 5C collet is for stops - this is a standard feature on 5C collets. Hardinge invented the 5C - the "c" stands for catarac - the name of the the river or water fall behind their original building location. Hardinge collets are the best next would be Royal, Lyndex Precision, Bison, Lyndex regular, the others in that order. check their sites out www.hardingeworkholding.com www.royalprod.com www.lyndex.com

[Stepside]

Most quality 5-C collets have an internal and an external thread. I have some "off brand" 5-C collets without the internal thread. No big deal until you start using collet stops, then it is the drizzly poops.

[Uncle Dunc]

The internal threads allow the use of a collet stop, but don't require it. The stop is a way of seating multiple work pieces to the same depth, or the same work piece multiple times, if you need to do that. If you're not going to be doing production turning, the lack of internal threads may never be an issue. However, as Thrud and Stepside noted, the collets you can get without internal threads are not likely to be very good ones anyway.

There was a 5C collet chuck project by Philip Duclos in the first issue of PIM. It was for lathes with 3/4" or 20mm holes through the spindle, and used the internal threads for the drawbar. The drawbar was hollow, so you could still fit 5/8" diameter stock through the spindle with the drawbar in place. The advantage was less overhang and much less mass than the kind that have the collet closer on the front of the spindle.

[Thrud]

All

It is pretty tough to beat one of those sleek new Bison 5C Chucks though - they tighten with a chuck key like a normal chuck so the internal stops can still be used. This leaves whatever maximum bore your lathe spindle has open for feeding bar stock to the collet. New England Brass & Tool have a fairly good deal on them www.brassandtool.com

You can never go wrong buying a Bison brand product - very well made and a steal for the money!

Disclaimer: I have nothing to gain from this - just suggesting a good supplier that advertises in HSM.

[msrm]

Decoy, I have some real Hardinge collets that do not have internal threads. I also
have the collet stop by Hardinge that uses
radial moving pins; the pins move outward and hold against the the wall of the collet
to hold the collet stop in place. You then
adjust the actual part locator/stop for the
job. I don't like the collets without the
internal threads because I don't trust the
stop that holds radially, it might move while machinig.