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Clarkson Chuck - removing the centre

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Gray6220/08/2010 15:26:19
1057 forum posts
16 photos
   I have a couple of Clarkson autolock chucks which have fairly mangled centres, I have tried various methods to remove these to no avail.

Does anyone have any advice for removing the centres?

thanks in anticipation.
David Clark 120/08/2010 16:03:14
3357 forum posts
112 photos
10 articles
Hi There
Hefty press, try a local garage for a hydraulic one.
The Clarkson center I disassambled was a short Morse taper.
It took a lot to move it but it came out in the end.
Big bang as it released.
Then you can regrind them in a cutter grinder.
regards David

Edited By David Clark 1 on 20/08/2010 16:12:37

Alan Parker 122/08/2010 21:17:13
1 forum posts
I removed the centre in one of mine recently by supporting it on something really solid (NOT) the back of your vice ! I used a thick concrete slab, and then by using a heavy lump hammer and a well fitting pin punch give it a heafty blow with the hammer and it will come out of its short morse taper. DON'T forget your eye protection for safety !
Gray6223/08/2010 18:49:30
1057 forum posts
16 photos
HI guys,
thanks for the advice, but I have already tried both methods, my son put them in a 50T press in his workshop and failed to remove the centres!!, so a hefty blow wiht a 14Lb sledge was really a gratifying but in realiity a uneventive attempt  at removing the centre. These centre have been in place for a very long time and I suspect will be very difficult to remove without some extreme persuasion.
I think it is time for extreme measures, I've got nothing to lose as I have a number of other chucks ( very fortunate to acquire several in a workshop clearance deal) so brutality may prevail, but thanks for the suggestions.
John Olsen24/08/2010 02:00:02
1240 forum posts
94 photos
1 articles
I haven't had to remove one of these centres, but have had a bit of experience with stuck things. If just pressing won't work, don't get too brutal too quick. Sometimes a few cycles of heating and cooling to moderate temperatures will help persuade things, especially if you are able to get it warm and then try applying a bit of force. Sometimes gentle tapping over a long period will give things the message.  Patience can sometimes work wonders, and if it doesn't , well maybe you can spark erode the offending centres away!
Gordon W24/08/2010 10:06:14
2011 forum posts
I don't know about your chuck, but the advice above often works. If you can , try freezer spray on the centre. When warm put into parrafin bath ,and hope it wicks up.
Chris Trice02/11/2010 00:16:12
1375 forum posts
10 photos
I'm going through the same pain right now. I'm damned if i can get the centre out. I've tried pressing, the hot/cold treatment, nothing seems to work. I now have the problem where I was using a length of silver steel to drive out the centre which has now belled out at the bottom so much, I can't extract it. Argh!!!
Steve Garnett02/11/2010 10:07:08
837 forum posts
27 photos
I spent a 'fun' three hours parting a Clarkson collet chuck pin earlier this year. Tried all of the above, and soaking it in the remains of the Plus Gas (can you still get this?) but what finally shifted it was the sledge hammer and the really solid base. It's the inertia and really rapid transfer of energy that does it - this is what a 50 ton press simply can't achieve - unless it's dropping 50 tons at the speed of a sledge hammer straight onto your chuck, and I don't want to be anywhere near that when it happens...
ady02/11/2010 10:42:10
612 forum posts
50 photos
If a 50T press wont move it then its time to bring out the blowtorch.
Heat and cool it to extremes(as far as is sensible) a few times.
A sledgehammer  on a concrete base is more fun though, and a lot faster.
....set it up and....bam!
(whilst wearing eye protection of course)

Edited By ady on 02/11/2010 10:45:46

ady02/11/2010 10:57:21
612 forum posts
50 photos
  Do any heavily laden freight trains pass through your local area?
Nicholas Farr02/11/2010 11:08:38
3313 forum posts
1530 photos
Hi, another technique you can try is to get the pressure on it with the press and then heat the body with the pressure is still applied, preferably with a high heat hot air gun. Be ready for a big bang.
Regards Nick.

Edited By Nicholas Farr on 02/11/2010 11:30:10

Chris Trice04/11/2010 01:43:47
1375 forum posts
10 photos
Tried that with a blow torch. Didn't touch it. Next stop, the sledge hammer. Wish me luck.
Gordon W04/11/2010 09:57:47
2011 forum posts
I've never dismantled a Clarkson chuck, but plenty of tight shafts, bearings, king-pins etc. A good, hard and fast whack with a heavy hammer, on a good solid mandrel and placed on a good solid base, so the energy goes thru' the shaft to be removed, will almost always move it, without damage. It is my impression that a sort of wave is set up in the parts and allows a clearance to develop, but I'm open to ideas.
David Clark 104/11/2010 10:07:57
3357 forum posts
112 photos
10 articles
Having once removed a Clarkson centre, a single blow will not do it.
It took a long while and only succeded by using a 5 ton hand press and then not at the first attempt.
It did come out with a mighty bang though when it did come out.
I think it was a shortened 1 Morse taper when checked which made it easy to regrind in a cutter grinder.
Keith Long04/11/2010 10:37:25
877 forum posts
11 photos


Just a thought - I've never tried this on anything myself, least of all a Clarkson chuck -  but if the back of back of the chuck was filled with grease or oil taking care to get all the air out and then a high pressure grease gun with a suitable adaptor fitted to the open end to pressurise it might that have the desired effect. If necessary try the blowtorch on the other end as well while everything is at pressure - but minimise any residual airspace before you start and have something to hand to catch and mop up any flying grease/oil. My side lever grease gun can generate something over 5000psi from memory.


Chris Trice11/11/2010 01:27:16
1375 forum posts
10 photos
Can anyone suggest anywhere I can get a replacement centre from?
Chris Trice18/11/2010 18:21:22
1375 forum posts
10 photos
Having shelved the offending chuck through sheer frustration, today I at least managed to remove the jammed piece of silver steel rod I'd been using as a drift by threading the end that was sticking out a running a nut down it to draw it out. So three weeks later, I'm right back where I started. Maybe the conical point on the centre isn't as bad as I first thought it was?
David Clark 118/11/2010 18:53:19
3357 forum posts
112 photos
10 articles
Hi There
How about filling the chuck with oil and screwing a bolt in.
Sort of inbuilt hydraulic press.
regards David
Andrew Johnston18/11/2010 23:00:11
6575 forum posts
701 photos
I believe it is still possible to buy centres from Clarkson, or their successors, for some models of chuck. If you're interested I'll find out the details from a friend who tracked them down in an attempt to get a new centre for his old style 'C' chuck. They did send him one, but it didn't fit. In the end I made him a replacement from silver steel.
Chris Trice18/11/2010 23:55:19
1375 forum posts
10 photos
Thanks Andrew, I'd appreciate it. If I can just get the old one out, I'm fairly certain there's enough meat to clean it up with a light regrinding.
David, that thought occured to me but at the sort of pressures needed, I don't think the threads will seal sufficiently well. Before we go the press route, I'm going to try putting a short length of hardened steel rod inside and then screw in a new high tensile 7/16th UNF bolt to push against the rod making use of all the thread in the body so as not to strip anything too easily. I'm not hopeful but worth a shot.  BTW, I live in Petts Wood just a few miles from your magazine offices.

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