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View Full Version : 5C Collet Threads Question



Paul Alciatore
08-05-2005, 09:09 PM
5C collets are available everywhere in a wide variety of sizes and styles. Also a wide variety of devices that use them. So they appear to be a good choice for a general purpose collet collection. And I am thinking of making a holder for my SB for them.

It would seem that using the internal threads would be the easiest way to attach a drawbar to them. But, I can not find any standards for the internal threads. The external threads are listed in Machinery's Handbook and are pictured on all the catalog photos so there would be no problem in using them. But I would rather use the internal threads.

So my question is, are the internal threads standard? If so, what are they? Does anyone have any 5Cs without internal threads?

Paul A.

Forrest Addy
08-05-2005, 09:14 PM
I've seen them without internal threads but nowadays it seems most have them. That said, I wouldn't care to make a cetegorical statment on the subjecct.

The reason for an external tubular drawbar is you get all that diameter and length to "swallow" long work. It's handy; trust me. Owners of smaller lathes wishing to use 5C collets have to work with a smaller spindle bore so an internal drawbar may be the only practical option.

JCHannum
08-05-2005, 09:15 PM
The 5C collet external thread is 1.238"-20 TPI, the internal thread is 1.041"-24 TPI. Both are right hand.

The internal thread is primarily for installing collet stops for repeat operations, and many collets do not have them.

wierdscience
08-05-2005, 09:18 PM
Up,no I think JC just told us for sure.


Like Forrest mentioned if you do use the internal threads the very first job you use them for won't fit through as a given.

[This message has been edited by wierdscience (edited 08-05-2005).]

Paul Alciatore
08-06-2005, 02:02 AM
Thanks all. I am convinced on using the OD threads. It will just make the adapter a bit longer.

Paul A.

John Stevenson
08-06-2005, 04:55 AM
Not to start banging an old drum again but if you have to make a choice starting from afresh take a look at the ER range of collets.
Probably ER25 and ER32 are the ones most suited to HSM use.

Main advantages of ER collets are that there are no gaps as each collet has a 1mm or 40 thou griping range whilst staying parallel.
Most collets like the 5C's have a very short range and are only parallel for the stated size. Moving out of this range sends the collet bellmouthed.

Second advantage is that the ER collets are both workholding and toolholding. You see 5C's on lathes but never on mills. ER's can be used on lathes, mills and grinders taking advantage of having to handle odd sizes that could cause having to a range of collets that are hardly used.

One disadvantage that people tout is that ER's in a lathe can't handle long lengths.
This isn't true as you can buy faceplate type mount chuck that bolt on or can be directly machined.
These allow the full size of the collet to go thru the headstock.

John S.

Alistair Hosie
08-06-2005, 01:15 PM
I have a set of 5c collets for my lathe and my milling machine came with two sets of clarkson collets one metric one imperial I recently bought a chuck for ER32 collets and a full set of collets which I use mostly on my mill and I have also got a extension chuck with a set of er16 smaller collets for little stuff.My lathe comes with a clever device in the spindle is bored out to act as a collet chuck for 5c collets so I wonder why other manufacturers or or at least more of them dont do this they mostly seem to go for a morse taper spindle.Do you have a lathe with this same type of spindle (shaped as a collet chuck)and what is it Alistair