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Chuck numbers

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Andy777

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Another silly question......?

What are the numbers 1-4 on a chuck for.

I screwed the 4 bits in and wound it tight and they all lined up to the centre
But when I put a bit or wood in it only 2 bit met the wood first??? puzzled me now!
 

Silverbirch

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The numbers on your chuck should be matched with the corresponding numbers which will be stamped on each of the jaws. They should then tighten concentrically around your workpiece.

Ian
 

CHJ

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The Jaws (or jaw carriers ) should also carry corresponding numbers.
Dependant upon chuck manufacture jaw numbers may be on a side face or in the sliding grove.

The jaws and the chuck body numbers should be matched for maximum accuracy and the jaws engaged with the chuck scroll in the number order.

Just because the jaws meet together does not mean they are concentric with the axis of the chuck.
Rotating the chuck and observing the jaw edges against a fixed point should confirm correct alignment.

Ian beat me to it. :)
 

jumps

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all the above, and even then everything may not be concentric with the spindle (although on more expensive chucks you hope it wil be!) so match any returning work to the jaw, which you've matched to the carrier as above... :)
 

nev

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what puzzles me is theyve machined the individual jaws to match the individual sections of jaw, why dont they just machine them to all be the same size in the first place? surely its 4 times as much work making the individual ones fit?
 

CHJ

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nev":3qeux1o6 said:
what puzzles me is theyve machined the individual jaws to match the individual sections of jaw, why dont they just machine them to all be the same size in the first place? surely its 4 times as much work making the individual ones fit?
The rear of the 4 jaws or Jaw carriers are different as they have scroll pitch spacing matched to the actuating scroll behind them.

This is done as a set in production with the partially machined jaws aligned in a jig.

In use the jaws/jaw carriers need to be assembled in the same sequence as they were in the jig.

Likewise accessory jaws are turned in the round as a complete disc, and the location holes drilled to an accurate PCD and circumferential pitch.
They have to be machined on back and front and this requires a move of jigs/holding methods
The jaws are then split into four sections using yet another separate jig or holding method.

If production controls are very good then they will be identical, but any slight miss alignment for this second and third process may result in a discrepancy, hence the need to mark them and assemble them in the original order that they were machined in the round.

Individual accessory jaws are not machined to match specific jaw carriers, but by careful control of the quality of jigs etc. by maintaining a known reference, (the numbers) there is the likelihood that any discrepancies are kept to a minimum and one that is acceptable for wood working.

On a metal lathe requiring increased precision jaws are ground in situ on the lathe.
 

Phil Pascoe

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All my faceplates and drive centres have a mark on them so that I can re-align anything I have had to take off, just in case something is not quite concentric. It's probably unneccessary in most cases, but I was taught to do it at school, and the habit stuck.
 

Andy777

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Oh Look!!! Tiny numbers on the jaw set! Thanks again guys. I will now go and play!
 

Jonzjob

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I had an even greater surprise today when I decided that I would do a spring clean on my K8 and found out, when I stripped it completely down that it's a K10! I have had it for 10 years or so and always thought itw as the 8?

Now it's all cleaned and re-dry-lubed it don't arf feel better! Well worth the 30 mins to do it.

When I looked at the scroll cam followers it is totally clear why they are numbered and so very obvious. Mind you I have always mounted the jaws in order on the carriers when I have changed them for any reason. Then again, I am one who will always try to put the screws back into the same holes too..

Something to be aware of is that if/when you take your chuck apart you don't loose yer balls out of yer main chuck body under the scroll mechanism :shock: :shock:
 

PsyMan

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my long nose jaws seemed to come without numbers until I gave them a good clean and found that each one has an almost invisible punch mark on the bottom, one has a single dot, one has 2 dots etc.. very hard to spot but at least now they meet up properly when mounted. Cheap jaws with no instructions, they will get you every time :)
 

Andy777

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You would think that if you rounded something off then put it in a chuck it would spin nicely! Nope!

Still learning!
 

CHJ

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Andy777":101k8rcu said:
You would think that if you rounded something off then put it in a chuck it would spin nicely! Nope!

Still learning!
That's because the bit you have 'rounded off' is more than likely wood.

"Side Grain" compresses more readily than "End Grain" so straight off you have a discrepancy of resistance (give) between adjacent jaws without the variations as to what percentage of the grain orientation is present in your particular lump of wood.

That is why you see mentioned so many times about marking a piece in relation to the jaws if you intend to remount it, even then there is no guarantee that it will align perfectly the second time around.
 
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