Collet Chuck Question

rex@@txol.net (Rex B) wrote in news: snipped-for-privacy@news.txol.net:

They ride on a bearing, and therefore the guts turn within the ring the handle moves

You must be talking about the Sjogren (AKA, Hardinge-Sjogren, ATS-Sjogren ... "show-grin"), perhaps the finest collet chuck ever made ... and it's been made since 1-9 and 2-9.

The ring rotates with the chuck body, and drives the so-called "center gear" through a planetary gear system.

The "center gear" is what grips the collet itself, and draws it into the chuck body.

There is a key in the rotating part of the chuck, and the "center gear" rotates differentially with respect to the chuck body and the collet.

A very clever 75 y/o design which has stood the test of time.

There are also the Jacobs Rubberflex chucks, most or all of which tighten/loosen the collets with a ring around the periphery of the chuck and the Burnerd chucks which seemed to have had at least two versions - those that open/close with a T-shaped key (like standard drill chuck keys, but bigger) or a lever that stays in place all the time and allows the stock to be fed with the chuck in motion.

Mike

It depends on the type of chuck. The only one which I have

*direct* experience with is the one made by Bison (and others) for mounting to the spindle the same way a chuck mounts. And -- it has a key like that of a chuck which plugs into a pinion to tighten the collet, and is then (hopefully) removed before the power is switched on to the motor. :-)

These are normally used for adapting a smaller lathe to allow the use of 5C collets (which require 1-3/8" clear through the spindle, to allow the 1-1/4" drawbar tube to pass through.

Other that that, my personal experience covers:

1) Standard drawbar collets -- an adaptor in the spindle nose to close the collet, and a hollow drawbar which passes through the spindle to draw the collet in and close it -- by tightening a spindle to draw the collet in and close it -- by tightening a handwheel. 2) Lever collet closer. The lever is on the other end of the spindle, and is connected to the drawbar through a ball bearing race and a complex internal lever setup so moving the lever to the left draws the collet in to close it, and moving it to the right releases it. *most* of the assembly rotates with the spindle, except for the lever itself, and part of the bearing. 3) Screw-on nose caps to close collets like the ER double-angle series. The caps have an eccentric ridge and the collets have a corresponding groove to allow the nose cap to draw the collet out when loosened. These are typically tightened and loosened by bars stuck into holes in the body and nose cap to act as wrenches. These, also, must be removed before switching on the spindle motor. 4) Jacobs Rubberflex collet closers, which have a handwheel surrounding the closer assembly, which draws in a nosepiece.

I have seen *pictures* of (but never the actual device) ones:

5) Which are entirely on the bed end of the spindle, but still have a lever. the lever appears to usually couple to the mechanism through a groove, or a bearing, so it can pull and push on the actual locking mechanism. The handle does not rotate in this, either.

I hope that this helps. DoN.

I got a complete set of the Burnerd collets, a new lever type closer, and a used key type closer for $165.00 plus ahipping on ebay. The collets new are $165.00 each. The closers were for the L0 spindle nose. My lathes have the A6 spindle nose. I made an adapter from Durabar cast iron and steel. I just love the thing. A really high quality system. So, if you see a closer that uses a different type mounting than your machine don't ignore it. If it can be adapted a lot of money can be saved. ERS

Only if the holders have been disassembled and cleaned periodicly.

John

That's a *really* great deal. I've got both the lever & keyed Burnerd chucks for L00 spindles with two sets of collets in separate deals and they were a heck of a lot more than $165 for the two lots. Have prices for thechucks and/or collets been dropping lately?

Mike