I'd say that's a Medium S Type chuck on an MT3 Taper. It looks identical to the one I sold a couple of years back due to not being able to find any collets other than a 1" one that I had. In the approx 1 year that I was monitoring ebay for collets, I dont think I ever saw anything other than 1" (at a price I was willing to pay)

Clarkson part numbers for the medium chuck range are

• 40094 – 1" Collet
• 40095 – Spanner Medium
• 40096 – Medium Damping Ring
• 40097 – 25mm Collet
• 40098 – 3/4" Collet
• 40099 – 20mm Collet

Hope this helps. Good luck in the hunt for collets.

Graham

For more info,

Small Collet O/D = 7/8"

Medium Collet O/D = 1-3/8"

Large Collet O/D = 1.683"

Graham

The ring at the top with tommy bar holes is a Damping Ring the purpose of which is explained in the instructions as follows:

"The purpose of these rings is to give stability to chucks which have small tapers and relatively large overhang below the machine spindle. The chucks listed are supplied with a left-hand thread on the back face of the body to which the rings can be fitted. When the damping ring is screwed onto the chuck and tightened back against the machine spindle nose it greatly improves the stability of these particular chucks."

Although Clarkson do not mention it the ring can also be used to eject the chuck from the machine spindle provided the draw-bar has not been over tightened.

Steve,

I think at some point Clarkson must have changed the name of the large chucks with a taper gauge of less than 1/2" to medium to remove confusion about collet sizes. The 1" collet for the large chuck with taper gauge of less than 1/2" is a completely different size collet to the 1" collet for the large chuck with taper gauge of more than 1/2".

This applies to all of the 803XX series from the table above. The body diameter is smaller than the other large chucks, and the collet O/D is smaller than the other large chucks.

The full range of collets for the three chuck sizes are

Small 6mm, 8mm, 10mm, 12mm, 16mm, 1/4", 3/8", 1/2", 5/8"

Medium 20mm, 25mm, 3/4", 1"

Large 20mm, 25mm, 32mm, 3/4", 1", 1-1/4"

Looking at the clarkson part numbers, the 8mm Small, 20mm Large, 3/4" Large and all medium collets all appear out of sequence with the other original collet part numbers, so these may have been introduced after the above clarkson images were produced. I'm guessing the extra collets were introduced at the same time as the range was changed to small, medium and large.

Cheers

Graham

Graham,

Thanks for educating me with that extra explanation of sizes. I agree that my image must be from an older document.

I have never seen a 3/4" or a 20mm collet that fits my R8 "large" chuck. And I have sorted through quite a lot of collets at various dealers looking. Nor do I have any endmills or slot drills with that size shank. At the risk of "being an anorak" the reason I have looked is out of curiosity as I do have a 8mm, 20mm, and 3/4" collet (amongst others) for my clarkson T&C grinder air bearing flute grinding attachment. Those P/N's are also out of sequence so again that points to a later product.

To aid the thread as a future reference I will add that I also picked up a number of replacement centers as a lot all P/N 40102 and these fit the R8 small and MT3 small (as in miniature, small, large). I have yet to see what my R8 large takes as the center is in vgc.I also include a picture with some of the other types of accessories. Are there others?

Steve

Clarkson part numbers for chucks. Hope they are of use. There's probably some gaps which you may be able to work out. e.g I reckon my 3MT Large Chuck is actually part number 80103 etc.

Edited By Graham Wharton on 08/04/2015 21:43:29