What type of Collet are these please?

Hi,

A friend has a number of collets but doesn't know what type they are - or what they'll fit. Can anyone shine any light please - many thanks.

Brian

(I hope the photos will appear - I struggled to attach any piccies)

Edited By B Tulley on 29/04/2022 16:50:19

They're dead length collets. Looking at the size I'd hazard a guess they're for a 3/4" Britan repetition lathe. I don't think I have any for direct comparison as I sold the ones I had since I have a 1-1/4" Britan.

Andrew

They look remarkably like Britan collets, Andrew beat me to it !

Edited By Baz on 29/04/2022 17:20:51

Many thanks for the replies - does this mean they are only really of use on a Britan Lathe?

Most likely yes; superficially the collets look like the DIN6343 standard, but don't match any of the standard sizes. At least that is the case for my collets for the 1-1/4" Britan.

If indeed they are for the Britan they have some value. The Britan is useless without collets and the 3/4" version seems to be rarer than the 1-1/4" version. What shapes/sizes are available?

Andrew

There's about half a dozen, ranging from 3/16" up to 1"; I can check actual sizes of all if that's useful. Which part of the collet refers to the 3/4" or 1.1/4" size?

It is usually the largest diameter of bar that the collet can accommodate.

Also often used in milling diving fixtures, milled lots of hexagons, fork ends etc using these on horizontal mills a great many years go !

Thanks, I've got a pretty good range of imperial round collets, but am looking for smaller hexagon and square. Although I sold my 3/4" collets I kept what seems to be a shop made adaptor so one can use 3/4" collets in a 1-1/4" machine.

As to the sizing there is nothing on the collet that says it is for a 3/4" or 1-1/4" machine. But as Baz says it simply relates to the largest round bar that can be accomodated. So the larger collets can't be for a 3/4" machine. It would be useful to see a 1" capacity collet with sizes. I can then compare with one of my collets.

Andrew

Is it one of these? A is the maximum diameter of the collet, B is the overall length, C is the diameter of the register and alpha is the angle of the taper from the centre line.

Martin C

Many thanks - no, none of those sizes.....

Brian

This is just a snippet from a 32 page list. If you give the actual dimensions I may be able to find something that matches. Trying to judge from a photo is not too easy.

Martin C

Many thanks - the dimensions are:

A: 31.34mm (there are four flats on the largest diameter, at the 90 degree points; these measure 30.49mm)

B: 45.93mm

C: 22.97mm (I'm assuming the "register" is the shiny ring at the right of the photo above)

alpha: 15 degrees

Kind Regards,

Brian

Oops, I got A and C the wrong way round. I've looked through the lists in two Crawford Collets catalogues and could not find a match for what you have. Apart from the overall length they are a close match to the Britan ones above and that is the nearest I could find.

Martin C

Many thanks for your help Martin, and to all those who posted; I'll be seeing the owner this afternoon and I'll be able to pass on the information. He doesn't own a Bristan (and is never likely to) so I'm not sure what he'll choose to do with the collets - but at least he knows what they are!

Kind Regards,

Brian