Collet Chucks out of true

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Collet Chucks out of true

This topic has 40 replies, 22 voices, and was last updated 12 August 2019 at 19:47 by Grizzly bear.

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4 August 2019 at 09:43 #422516
Iain Downs
Participant
@iaindowns78295
A while back I bought an Mt3 ER2 collet chuck from eBay which I've not used much until recently.

Whilst turning some 12mm silver steel I noticed a wobble and checked it out.

I found the body of the chuck had a wobble of 0.06mm and that amounted to 0.6mm at around 200mm from the chuck face.

I looked around at alternatives from reputable UK manufacturers and found them to be around 3 times the price.

So I thought I'd have a punt and hope that mine was a Friday afternoon job and bought another one.

Guess what?

This one had a relatively small wobble, though it took the form of a depression around 45 degrees of rotation with the rest being pretty solid.

I measured both chucks again, this time with a 16mm test bar. Chuck number one showed a wobble of 0.36 mm 40mm from the chuck face (110mm from the spindle face) and number two was much better (!) at around 0.15 mm.

I put a test bar in the taper and measured wobble at the same place relative to the spindle face (110mm out). This showed more or less no deviation (under 0.01mm) except for a tick which probably a defect in the test bar (which I regret to say has managed to rust).

I also tried turning the chuck in the spindle and that established that the error was in the chuck not the spindle.

So I expect the advice from the assembled will amount to, 'if you buy cheap, you get sh*t', which seems correct. But what should I expect? ANd what do I need to pay to get a decent quality?

And is it likely that the collets are the problem rather than the chucks?

Many thanks

Iain
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4 August 2019 at 09:43 #13603
Iain Downs
Participant
@iaindowns78295
How much do I have to spend?
4 August 2019 at 09:57 #422520
Philip Powell
Participant
@philippowell34749
Iain. Have you tried removing the collet and measuring the runout on the inside face of the chuck? Within reason it doesn't matter if the outside of the chuck is not true. This should determine if it's the chuck or collets that's causing the problem.

I presume you have a ER32 church not a ER2?

Phil.
4 August 2019 at 10:20 #422525
Iain Downs
Participant
@iaindowns78295
HI, Phil.

I think I did and I think it was out. However, I will check that a bit later on.

Iain
4 August 2019 at 10:27 #422527
SillyOldDuffer
Moderator
@sillyoldduffer
Trouble with buying bargains from ebay is there is no correlation between the source and quality. It's like a car-boot sale, anything from a genuine Picasso for 10p to fakes being sold by a fly-boy at top prices. I've done OK on ebay (and similar), but it doesn't surprise me when the odd dud turns up. It's a bit of a gamble. Mostly I've come out on top but I'm always ready to write-off the odd duff purchase.

Your bent chucks may be from a batch of rejects, not just a Friday aberration. All the factory duds collected together and sold on to an ebay vendor …

The advantages of buying from the UK sellers is being in the trade they have a better chance of selecting reasonable goods in the first place and – if it's wrong – you can usually get a refund without too much fuss. The downside is they are more expensive. Mostly, I buy tools from them. But even these are hobby supplies, not the best available, which also introduces an element of risk. So far I've not had to send anything back, but…

Sellers of professional quality ER collets and chucks tend to be coy about prices but – as an indication – a Roebuck collet chuck can be had for £108 + VAT, with collets £10 to £30 each. Or more. It may not be worth the extra money; certified accuracy is a comfort but you could also be paying for tools rated for use in a 20000rpm CNC machine; completely wasted in a home workshop. I'm afraid new top-end tools are seriously expensive.

Dave
4 August 2019 at 10:27 #422528
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Philip Powell on 04/08/2019 09:57:53:

.

I presume you have a ER32 church not a ER2?

Phil.

.

Typos abound ^^^

[ well, It is Sunday ]

MichaelG.
4 August 2019 at 10:45 #422533
Old School
Participant
@oldschool
One thing I have found with ER type collets is the range the have for example 11 to 10mm it is accurate at 11mm and a bit under but nowhere near as accurate at 10.1mm.

I have moved to 5C collets now and use emergency collets for the odd sizes that I need to hold.
4 August 2019 at 11:05 #422536
Kiwi Bloke
Participant
@kiwibloke62605
There's been quite a bit of relevant discussion about these things in this forum already. If clocking the chuck taper suggests the chuck is 'out', it's a dud. The collet may also be 'out'. However, it has been pointed out that, even good-quality collets can't be relied upon to be perfectly aligned when the chuck is tightened. Applying a balanced torque (couple) to the nut may help. Collet 'pushers' are available. These are used to apply a temporary, radial force to what the collet's holding, as the nut is tightened. (Tighten a bit, clock it, tweak, tighten, rinse and repeat…)

As I understand it, these chucks were originally designed to hold cutters, not workpieces, so absolute alignment wasn't such a priority, given the short length of (most) cutters.
4 August 2019 at 11:05 #422537
Tony Pratt 1
Participant
@tonypratt1
Unfortunately the world is full of crap tooling/washing machines/electrical goods etc. etc. etc., it's the way of our world at the moment.

You get an item but it's not quite right so what do you do, use it or return it???

Tony
4 August 2019 at 11:12 #422538
Kiwi Bloke
Participant
@kiwibloke62605
'You get an item but it's not quite right so what do you do, use it or return it???' Good question, Tony. I suspect it depends to whom you try to return it. The people who understand that quality matters seem to be dying out – at least in the retail sector.
4 August 2019 at 11:45 #422541
Pete Rimmer
Participant
@peterimmer30576
How hard is the material? Too hard to turn a new taper with carbide? That's what I would be looking to do if it's not getting returned.

Think of it as making yourself a collet chuck except someone else has done the roughing out
4 August 2019 at 13:25 #422553
old mart
Participant
@oldmart
I have bought two er25 collet holders in R8, the first had a wobble, so I took a chance and bought another which is good. They were both cheap Chinese, but clearly made by different companies. Getting sets of the collets is also a lottery, I ended up buying Vertex and Cutwell collets in 6, 8, 10, 12 and 16mm which are good.
4 August 2019 at 14:50 #422566
John Baron
Participant
@johnbaron31275
Hi Guys,

The biggest problem with Chinese ER collets is that they are not properly cleaned and deburred. I've found that there are often tiny burrs left after they have been slit. In some cases large slivers of metal have been left.

I use a Stanley knife blade to clean mine and remove the swarf that has been left. After cleaning properly all the ones that I have used have been in spec. I posted pictures on another forum of the worse ones I had.

Stoning the burrs off is easy on the larger collects, not so on the small ones.
4 August 2019 at 17:41 #422576
Vic
Participant
@vic
I bought the majority of my ER32 collets from Arceurotrade and haven't had any with defects like burrs etc. I’ve not checked them for accuracy though.
4 August 2019 at 17:59 #422579
Mick B1
Participant
@mickb1
I'm glad I read this thread. Looks to me as if collet chucks are not only very limited in range, but also little or no better than a good 3-jaw for concentricity. Apart from repetition bar work that'd be better on a capstan, I can't understand what some people see in 'em.
4 August 2019 at 18:44 #422583
Pete Rimmer
Participant
@peterimmer30576
Good collet chucks and collets are very repeatable. Far better than a 3-jaw.
4 August 2019 at 19:57 #422590
Philip Powell
Participant
@philippowell34749
As Pete says a decent collet chuck should be very repeatable. In my experience they are very accurate (useally) they will hold work firmly without damaging the surface and with care thin walled components can be held.

Phil.
4 August 2019 at 20:47 #422598
Neil Wyatt
Moderator
@neilwyatt
There are lots of different qualities; to an extent you get what you pay for.

Mine are a mix of secondhand and Arc ones, and I haven't had any with swarf or burrs on.

Expecting concentricity with 8" of overhang in an ER collet seems optimistic even with the most expensive of precision collects, although you ought to be able to get better than 0.6mm.

Neil

Edited By Neil Wyatt on 04/08/2019 20:47:41
4 August 2019 at 20:52 #422601
Tim Chambers
Participant
@timchambers76147
At the risk of teaching granny to suck eggs, you did throughly clean the morse taper in the spindle first?

Its very easy to just bop the chuck into the spindle and tighten the drawbar and forget to check if the taper has any swarf buildup.

Edited By Tim Chambers on 04/08/2019 20:54:51
4 August 2019 at 20:56 #422603
JasonB
Moderator
@jasonb
Iain, I wonder if some or all of the error you are getting is from incorrect fitting of the collet. looking at some of your photos it looks like the collet is sitting way to far back into the nut.

The collet should be snapped into the nut and then the two fitted to the chuck, our good friends ARC show how to do it here
4 August 2019 at 21:33 #422610
Meunier
Participant
@meunier
Well spotted JasonB !

separately, when I saw ER32 Church I wondered whether it might be another of BrianWood's projects (enjoyed the article, by the way)
DaveD
4 August 2019 at 22:05 #422613
Vic
Participant
@vic
Well spotted Jason.
5 August 2019 at 07:30 #422627
Iain Downs
Participant
@iaindowns78295
Thanks all.

I had cleaned the MT3 taper in the spindle and I had learned about snapping collets the last time Jason told me off (;)!

But always good to check…

Next time I'm in the shed, I'll check the taper of the chucks – probably at two places (depths in the taper) and also check the colletts for mess.

I suppose that I can check the wobble on several bars with different colletts and if they are all similar it's the chuck if they are wildly different it's the colletts.

Iain
5 August 2019 at 20:55 #422761
Iain Downs
Participant
@iaindowns78295
I've measured the 'wobble' / run out on the ER32 tapers and they run to around 0.08mm.

I've also double checked the spindle and there's none (to the limit of my ability to measure.

So the chucks aren't brilliant.

I'm up for attempting to re-machine the ER32 taper in principle, but concerned it will end up scrap.

How I would approach this is as follows.

wind back the topslide, loosen the bolts holding it and set to exactly 8 degrees with my aldi angle gauge.(actually it will be 98 degrees as I will measure against the cross-slide edge).

put in the dodgy chuck and tighten up with the bolt.

take fine cuts at high speed (1500rpm?).

Try measuring again.

From what I can make out if the angle is within a few tenths should kind of work. Mr Hall mentions 'within a few degrees' but that seems implausible.

Do you think that would work OK?

Iain
5 August 2019 at 21:09 #422763
John Baron
Participant
@johnbaron31275
Hi Iain,

I would double check everything, 0.08 mm is 3.2 thou that is an awful lot of runout !

I get an average of 3/10 ths of a thou at 3 inches. And that is after I've cleaned everything and made sure that there are no burrs anywhere. A clue to having a burr in a collet is tiny scratches on the work. Similar on the edges of the chuck. Check the collet for scratches.

Edited By John Baron on 05/08/2019 21:10:13
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