Clarkson autolock again .....

Hi,

Well I give up. I obtained a Clarkson S autolock chuck and whilst it was on its way I bought a collet to go in it ( the chuck was just that, no collets or spanner). As you might expect the collet didn't fit - I thought I was getting a small model s chuck and a large one arrived. Ho hum silly me. So I got a 1 1/4" collet instead and blow me that doesn't fit either. The chuck is definitely a Clarkson and the outside dimensions match those for a large chuck. The collet looks like a Clarkson but is too big. It is also 32mm but that is another story. There is precious little data on Clarkson chucks on the 'net.

The chuck has an outer ring screwed on the body with Tommy bar holes, has a 3MT arbour and the number 40096 engraved on the back of the ring. The body is also engraved with Clarkson S and a patent number. The outside diameter of the collets needs to be 1 3/8 as near as I can measure it.

Before I spend any more money on collets can anyone tell me what I have got and what specification of collets I need to obtain?

All the best.

Tim

Edited By Tim Ostley on 07/04/2015 19:56:58

Edited By Tim Ostley on 07/04/2015 19:58:08

Edited By Tim Ostley on 07/04/2015 19:59:14

Any chance of photos?

Tony

iPads are not the greatest for this but .....

Tim you will need to host them elsewhere or create an album on this forum

Second attempt ....

Edited By Tim Ostley on 07/04/2015 20:29:17

Maybe this will help. The capacity of the large chuck depends on the size of the taper it seems.

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

And this will give you where to measure the gauge line.

I would say MT3 has a smallish gauge dia so you could have a large holder that will only thake a 1" collet

Thanks for all the info guys. It looks like a medium autolock (didn't realise there was such a thing). I guess that the 3/4" and 1" collets for the medium and large chuck are different. Ho hum.

Tim

Do not despair, unless you are going to be seriously out of pocket,you may consider making a series of bespoke inserts to covert the chuck into a sidelock holder, fly-cutter, boring bar, etc., etc. It looks a sturdy bit of kit.

Roy M.

Edited By Roy M on 07/04/2015 21:11:05

For more info,

Small Collet O/D = 7/8"

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

Large Collet O/D = 1.683"

Graham

Home and workshop machinery often used to have these chucks for sale, maybe they have spare collets?

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.

.

Tim,

In the interests of increasing the data available on the 'net ...

Could you please quote that patent number.

Many thanks

MichaelG.

As requested, the engraving on the chuck says:

3 MORSE TYPE S

BR PAT 915713

ENGLAND 1/2 BSW

Tim

P.S. If anyone has any of the 4 collets made for this chuck, do get in touch!

Hi,

If all goes well you will see an image below my text. Hopefully this will add to the thread.

Since you have a MT3 chuck taper you could have a miniature, small or large collet chuck. I can't be 100% sure if its a small or a large from the picture. MT3 (and R8) large are limited in that they only work with 1" and 25mm collets because the taper gauge line is smaller than 1.5". So you would be looking for a 1" or 25mm collet.  normally the large autolock chucks came with 2 collets in the Imperial version a 1" and a 1 1/4" or Metric version with 25mm and 32mm.  Originally there are 2 cutouts in the foam in the box for these two collets. The exceptions are this more limited shank types e.g. MT3 & R8 came with both  a 1" and a 25mm. I.e. you still got your 2 collets but the set is both Imperial and Metric but the set omits the largest sizes.  The information in the thread will enable you to confirm definitively if you have a small or large chuck. If you have a small then you are looking for in Imperial 1/4", 3/8" 1/2", 5/8" and Metric 6mm, 10mm ,12mm, 16mm. These small sizes collets are readily available from dealers and ebay.co.uk. Where are you? Perhaps a local dealer may be able to help?

Steve

Edited By SteveI on 08/04/2015 20:23:27

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

.

Thanks for that, Tim

Here it is

MichaelG.

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 Collets and Chuck Spares. Hope they are of use.