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Pillar Drill Accuracy - Do I need a new chuck?

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AndrewG

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A little advice please

I have had a benchtop Axminster pillar drill for 10+ years - the fore runner of the Axminster WD16SB Bench Pillar Drill I think. However any drill has always had a distinct wobble, that does nothing for accuracy and makes drilling large holes slightly alarming due to the vibration.

Today I finally used a borrowed dial gauge to try and work out where the problem was. Running it against the shank of the drill just below the chuck confirmed I am getting 0.5mm of wobble there. Everything else seemed to spin with less than 0.04mm of wobble, even the drill chuck arbor when I separated it from the chuck.

So I concluded the arbor was not seating straight in the chuck's tapered hole, but cleaning and reseating it made no improvement. I did try a friends chuck and that gave a wobble of 0.2mm on the drill, so pretty sure the chuck is the biggest culprit

So two questions for anyone who knows about these things:

1. Is there anything I can do to try and improve the arbor to chuck alignment (at least some encouragement before I hit it with a hammer!)

2. Should I just buy a new chuck, and if so are there any recommendations, things to look for ?
 

Carlow52

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Unlightly but is there anything stuck up at the back of the jaws of the chuck stopping it from tightening evenly on the bit.
When u tighten a bigish bit are the the 'grippers' protruding evenly from the chuck.
 

CHJ

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AndrewG":3j7crvwq said:
.......
Today I finally used a borrowed dial gauge to try and work out where the problem was. Running it against the shank of the drill just below the chuck confirmed I am getting 0.5mm of wobble there. Everything else seemed to spin with less than 0.04mm of wobble, even the drill chuck arbor when I separated it from the chuck.
If the drill chuck arbour is running true, and it seats firmly in the chuck socket then that points to a fault in the chuck. Be that a machining fault in the body or the set of jaws.

AndrewG":3j7crvwq said:
.......
So I concluded the arbor was not seating straight in the chuck's tapered hole, but cleaning and reseating it made no improvement. I did try a friends chuck and that gave a wobble of 0.2mm on the drill, so pretty sure the chuck is the biggest culprit......2. Should I just buy a new chuck, and if so are there any recommendations, things to look for ?
You have answered your own question really. You checked basic alignments, you substituted another unit, which performed better, so you can do no better than replace your chuck.

I would say this is the way to go.
If the chuck had run true from day one then you look for something that has changed in the way of debris/wear etc. that could account for mis-alignment but as you say it has never run true then ditch it.
 

Jacob

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Maybe everybody does this anyway - but I was told to always tighten with the chuck key using all three holes one after the other, to even out pressure and centre the bit. Might help. Perhaps locate the jaw which is most out and file a bit off its face?
 

Tom K

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Jacob":tgrgo2o7 said:
Maybe everybody does this anyway - but I was told to always tighten with the chuck key using all three holes one after the other, to even out pressure and centre the bit. Might help. Perhaps locate the jaw which is most out and file a bit off its face?
On a drill chuck Jacob? How would using each hole make a difference :?
 

Jacob

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Tom K":2doye779 said:
Jacob":2doye779 said:
Maybe everybody does this anyway - but I was told to always tighten with the chuck key using all three holes one after the other, to even out pressure and centre the bit. Might help. Perhaps locate the jaw which is most out and file a bit off its face?
On a drill chuck Jacob? How would using each hole make a difference :?
Each time you use the chuck in you are exerting pressure on one of three sides. If there is the slightest bit of slack (which there will be, especially of worn) this could slightly tilt the outcome, I would have thought.
Dunno, it's not my theory but maybe it's worth considering?
 

Phil Pascoe

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Think about it - try it. If you tighten hole 1 as far as it goes then you tighten hole 2 and hole 3 and the key actually moves at all, there must be slack somewhere.
 

Jacob

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phil.p":1036x30d said:
Think about it - try it. If you tighten hole 1 as far as it goes then you tighten hole 2 and hole 3 and the key actually moves at all, there must be slack somewhere.
But in tightening hole 1 you could remove all slack, but off centre a touch?
 

Hitch

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I tend to do all three up , especially if its a well used chuck.
 

CHJ

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On any chuck where a scroll mechanism is used to close the jaws applying pressure to the individual actuating gears/key sockets tends to centralize the scroll and improve accuracy.
On machine chucks we always had to use independent jaw chucks for maximum alignment accuracy but when this was not needed we progressively pinched up on all three points around the chuck to get as central as possible.

But judging by the OP's problem I suspect he either has a jaw not machined to match the other two or the body of the 'jacobs' chuck was misaligned when reverse machining the block.
Most 'jacobs' chucks have enough slack and movement in the mechanism to feed the jaws correctly regardless, as long as the front carrier coves are machined true to the rear attachment taper.

A cheap chuck with a loose actutating collar can be encouraged to run as true as possible and vibrate less by using the key in all three positions to centralise the collar and the scroll attached to it.
 

Cheshirechappie

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That is a fairly large error for even a non-precision chuck.

It's sometimes possible to dissemble chucks to clean and inspect components. It sounds like either a gross manufacture fault, or a cob of hard dirt lodged where it shouldn't be. However, if you can't get it apart (and some chucks do need a bit of knowledge and some special tools to strip them), sling it and get a replacement.

Jacobs chucks are very well regarded, but tend to be pricey. They will, however, give impeccable service for very many years, and will even take a degree of abuse.
 

Tom K

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Jacob":1d5lu0l9 said:
Tom K":1d5lu0l9 said:
Jacob":1d5lu0l9 said:
Maybe everybody does this anyway - but I was told to always tighten with the chuck key using all three holes one after the other, to even out pressure and centre the bit. Might help. Perhaps locate the jaw which is most out and file a bit off its face?
On a drill chuck Jacob? How would using each hole make a difference :?
Each time you use the chuck in you are exerting pressure on one of three sides. If there is the slightest bit of slack (which there will be, especially of worn) this could slightly tilt the outcome, I would have thought.
Dunno, it's not my theory but maybe it's worth considering?
It doesn't have three sides Jacob its a cylinder. When tightening nuts and bolts, do you feel the need to alternate which flat the spanner is used on to tighten it evenly?
 

CHJ

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Tom K":e4o5pogn said:
It doesn't have three sides Jacob its a cylinder. When tightening nuts and bolts, do you feel the need to alternate which flat the spanner is used on to tighten it evenly?
Tom you are missing the point, the actuating sleeve is a cylinder as you say, as is the scroll split nut which is an interference fit on its inner surface.
But the significant factor is that if this cylinder combination is a slack fit on the male scroll teeth on the jaws and/or the core of the body that they are located in, then that cylinder can position itself off centre if you apply max pressure from just one facet of the three key points, by applying a tightening force progressively around the three key locations you stand a chance of centralising the sleeve and its attached scroll and obtaining maximum chance of things running true.



Edit:- the above image taken fro HERE one of the clearest set of breakdown images I know of.
 

Tom K

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Surely all you are doing is attempting to centre the cone by turning the chuck through 360 as you tighten it down. The actual position of the chuck key doesn't have any real consequence (hence popularity of keyless chuck). If you need to do that with a chuck it really is past its best.
 

AndrewG

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Thanks guys for the suggestions - I think I have cleaned everything thoroughly and the chuck jaws tighten evenly together, so from Chas's impecable logic it does appear that the Jacob taper hole in the back of the chuck must be machined off axis.....

I guess I was finding that hard to believe, but having reassembled the arbor and chuck a dozen times and always got the same misalignment, I do think that conclusion is inescapable. I now like the sound of Axminster's Super Precision Drill Chuck, if only it was in stock. Didn't realise Jacob was still an available make, but for woodwork I am guessing their cost/precision is overkill - I just need one without any manufacturing faults!

Maybe I should have mentioned that the faulty chuck is a keyless one - but then I would not have learnt this lesson about using all three holes for better alignment.

Thanks
 

CHJ

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AndrewG":2d3tp6hu said:
.....Maybe I should have mentioned that the faulty chuck is a keyless one - but then I would not have learnt this lession about using all three holes. I admit I was sceptical untill Chas gave us the photo.

Thanks
That makes a big difference to the possible reasons for runout of jaws as the operating principle is different.
It does certainly sound like poor initial machining of a main component.
Design of yours may vary in proportions and minor details but this is a typical design.
 

Carlow52

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phil.p":1bajd3v8 said:
So what happens if your body is o.k. but you have no balls and still need a jaw guide?
=D>

On reflection I would probably chuck it in.
 

jonclancy

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Hi Everyone,

Sorry for ressurecting an old thread, but Google led me here!

I have an Axminster ND16B I have had for a few years. It has the keyless chuck and can’t drill an accurate hole for toffee. I have checked the runout with some silver steel rod (horrid!), some drill bits and then removed the chuck and measured the arbor runout. That was much, much better. I don’t recall it being that bad when I bought it, so something has happened over the years. I have checked and cleaned the B16 taper, but am thinking of just getting a decent quality, keyed, replacement chuck.

I’m thinking of getting a Jacobs with a suitable new arbor, as there doesn’t seem to be a B16 version made by them. Before I jump in, are there any other quality brands I should consider, please?

Many thanks for any pointers!

Cheers

Jon
 
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