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C0 self centraling 3 jaw chuck.

OMG it's a nightmare already!

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Richard Cleaver07/11/2016 16:12:27
15 forum posts

Having took receipt of my first engineering lathe I have tried to reverse the reversible jaws supplied in the chuck and don't seem to be able to put them back in!

SWMBO is giving me discerning looks as she knows just how many shekels this has cost. Help please if there is a technique or order of process. I cannot even put them back in how they was! Nightmare!!

wheeltapper07/11/2016 16:18:14
419 forum posts
98 photos

you cant reverse jaws in a three jaw chuck because of the scroll curve, you should have an extra set for reverse gripping.

there is also a certain order they are fitted. they should be numbered 1 2 3 and they go in in that order,

look in the end of a jaw slot and you can see the scroll, turn that with the key until the end appears, insert jaw 1, go to the next slot and repeat, this is with the scroll turning anticlockwise looking at the front of the chuck and turning the chuck key clockwise.


hope this helps.



this doesn't apply to a four jaw independent chuck because they work differently

Edited By wheeltapper on 07/11/2016 16:23:33

Edited By wheeltapper on 07/11/2016 16:25:08

David Standing 107/11/2016 16:27:39
1288 forum posts
48 photos

Funnily enough I was putting a 3 jaw Burnerd back together half an hour ago after cleaning the previous owner's cast iron dust out!

Your jaws should be numbered 1,2,3; as will be their slots in the chuck.

Insert jaw 1 into its slot, wind the chuck key until the scroll thread JUST catches it. Insert jaw 2, carry on rotating the chuck until the scroll catches that one, repeat for 3.

Job done smiley.


Edited to say, I was typing whilst Roy was editing!

Edited By David Standing 1 on 07/11/2016 16:28:37

Neil Wyatt07/11/2016 16:44:47
17728 forum posts
697 photos
77 articles

The C0 is supposed to have reversible jaws.

They should be numbered but the slots may not be.

Place them all in the slots and wrap your left hand around the chuck so they are all being pressed inwards

Usually jaw 1 goes in the slot opposite the logo.

Turn the chuck key until you feel all three 'click' into place. At some point all three should site evenly protruding by the same amount. If you can't get them all even swap jaws 2 and 3 over and try again.

Once all three are even, tighten them up, keeping pressing them in until all three have fully engaged with the scroll.



Dusty07/11/2016 16:45:01
471 forum posts
8 photos

In theory it should not matter which slot the jaws go back into as long as they are in the right order. I have a 3 jaw where the slots are not marked at all, that has had the jaws replaced in all three configurations and it runs within a couple of thou wherever they are, and that's good enough for me. I understand that, I suspect days gone by, in the more expensive chucks the jaws were fitted to their respective slots by an experienced fitter.

steve de2407/11/2016 16:46:10
69 forum posts


DS 1 has given a good description on how to put your chuck back together with the jaws the normal way around.

Contrary to what Roy says you can get 3 jaw chucks with reversible jaws - I know, I've got one! You follow the procedure as given by DS1 except that the order you need to insert the reversed jaws is :-

Start by putting jaw 3 in slot 3.

Next, jaw 2 in slot 1

Last, jaw 1 in slot 2

At least that's what works on mine.


wheeltapper07/11/2016 16:51:48
419 forum posts
98 photos




Edited By wheeltapper on 07/11/2016 17:02:38

wheeltapper07/11/2016 16:55:27
419 forum posts
98 photos

Oh well, it looks like I stand corrected ( again)blush

I've never seen a 3 jaw chuck with reversible jaws, how does that work?

I think I'll keep my mouth shut in future.


Richard Cleaver07/11/2016 16:57:45
15 forum posts

Thanks both.

Have found numbers on jaws but none that I can see on chuck to correspond.

Jaws have all gone in so far and stiffened up. No chuck key btw, this is operated by two punch shaped levers. One for the chuck and one for the scroll(?).

Richard Cleaver07/11/2016 17:08:41
15 forum posts

Stand by.....getting some pics!

steve de2407/11/2016 17:11:54
69 forum posts

Roy, if you look on the back of a reversible jaw then each tooth of the 'rack' is convex on both its radial inner and outer faces, to engage correctly with the scroll.


John Stevenson07/11/2016 17:13:42
5068 forum posts
3 photos

They cheat and put two curves on the back of the jaw, one to match the inside jaws and one to match the outside jaws.

These chucks are the cheaper scroll chuck where you tighten then with pins in holes but having said that the chuck that came with my C0, a very early model is remarkable accurate.

There is another way of having reversible jaws and that is to have straight teeth on the back of the jaw and straight teeth on the 'scroll' hard to explain.

One company that makes these is Forkardt and they have a limited tightening range before you have to re-position the jaws. Made primarily for CNC machines that are on the same job over and over again these chucks are very, very expensive and have unique gripping power, you can actually crush a solid alloy bar in these chucks.

I thought I had some pictures of the jaws and the scroll but can't seem to find them.

Richard Cleaver07/11/2016 17:48:50
15 forum posts

Neil Wyatt07/11/2016 17:52:19
17728 forum posts
697 photos
77 articles

Are you pushing the jaws inwards to get them started? If not the end of the scroll will jam against them,. likely as not.

Richard Cleaver07/11/2016 17:53:22
15 forum posts

Pic1: As far as they go.

Pic2: Same. But showing the 2 levers for closing the chuck. Not knuckle friendly when adding a touch of grunt!

Pic3: Some signs of wear....and I've not turned it on yet!

Pic4: Numbers as clear as mud!

Yes I know I should of left well alone but I had a piece of ally tube to practice on and thought it safer to reverse the jaws and grip tube from inside. Best laid plans of mice....etc

Edited By Richard Cleaver on 07/11/2016 17:54:35

steve de2407/11/2016 18:00:10
69 forum posts


A dull clunk has gone off in my head when I look at the picks of your jaws - each of them has two jaw numbers on them (as well as the '215'.

One jaw is numbered 1 and 3

one jaw is numbered 2 and 2

one jaw is numbered 3 and 1

Note the difference between '1 3' and '3 1' is which number is closest to the working end jaw when used in normal or reversed mode.

Are the slots in the body of the chuck numbered? I can't see from the photo.

I think I'm close to how it works.


Richard Cleaver07/11/2016 18:07:22
15 forum posts
Posted by Neil Wyatt on 07/11/2016 17:52:19:

Are you pushing the jaws inwards to get them started? If not the end of the scroll will jam against them,. likely as not.

Thanks Neil. The scroll was indeed jamming the jaws. Now all jaws are doing up but 1 appears off centre to other 2 jaws. Swap jaws around maybe?

David Standing 107/11/2016 18:25:15
1288 forum posts
48 photos



Is no 1 jaw closer to the centre?

You may have just picked up no 2 and 3 jaws a scroll thread later than 1. Undo the chuck slowly whilst pulling on no 3 jaw, until no 3 comes out. Then continue to undo the chuck until no 2 comes out (sorry!). Then do the same until no 1 comes out.

Do the chuck up again whilst pressing no 1 jaw in. As soon as it catches no 1 so you can't pull it out again, insert no 2 whilst pushing on it, and turn the chuck to close it, until it catches no 2. Repeat for no 3 jaw. You should now have all three on the correct part of the scroll.

Edited By David Standing 1 on 07/11/2016 18:27:52

Edited By David Standing 1 on 07/11/2016 18:28:33

steve de2407/11/2016 18:46:37
69 forum posts

Richard and David,

I agree with David but note each jaw has two numbers on it. So start off by laying out the jaws in the order 1, 2, 3 using one of the sets of numbers (all at the inner end of the jaws or all at the outer end). I would try the set of numbers closest to the jaw when assembling it the 'normal' way around. If the jaws don't close down evenly then use the other set of numbers to decide which is jaw 1, 2 and 3. Whichever set of numbers closes the jaws evenly in the 'normal' mode then use the other set of numbers when the jaws are reversed.


Richard Cleaver07/11/2016 18:48:41
15 forum posts

Dear All, Success at last. Only taken me 4 hours! You've all been legends.

Stand by for tomorrow's thread entitled...How do I turn this f$£*&ng thing on!!! laugh

The wife has returned from 'being busy in the kitchen' with a glass of red for me and the dog has come from under the kitchen table and it watching me from under his eyebrows as if wary of raised voiced and choice words.

Thank you again!

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