# Loose Chuck Check



## wcndave (23 May 2012)

Something is not quite right here...

I have a 33 dedicated richard sorby chuck. I have a european Scheppach DMT 450












However if you watch the video, you'll see I appear to have significant wobble, and it's not a wobble chuck!

http://youtu.be/HNx3IBrPqq8

Before I go back to the toolpost, given it's taken 2 weeks and international delivery to get here, I thought I would seek out some opinions here...
It appears to be the diameter of the chuck that's wrong, not the TPI...


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## chipmunk (23 May 2012)

Hi Dave,
The looseness of the threads is not a big deal provided the back of the chuck can be tightened so that the back is flush against the step on the lathe shaft at the back of the threads. 

If the chuck is still not running true when this happens then you have a problem but the video doesn't seem to get that far, does it?

HTH
Jon


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## wcndave (23 May 2012)

I get the chuck on all the way, hence some video wobble while i try to hold the end with my elbow ;-)

However the first time i put on, i simply tightened fully (by hand, there is no other way), and it's not true at all.

I would have thought the threads would match pretty well, however if not, then the back of the head has to be exactly perpendicular, and also how would one center the chuck? gravity would have it down so that it runs parallel to bed, however in a loop...


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## jpt (23 May 2012)

The wobble as the chuck is put on is normal and nothing to worry about.

The important bit is that the back of the chuck fits tight against the back of the register on the lathe. Looking at the video this doesnt happen and there is a small gap this is why you are getting wobble, make sure the thread of both the spindle and the chuck are clean and try it again and the two faces should meet as this is what makes the chuck run true.

If there is still a gap get back on the Toolpost and make sure they have sent you the correct insert, as there are different ones for M33 x 3.5 lathes.

Another thing to try is make a washer to go between the chuck and register out of a plastic milk bottle or similar.

john


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## chipmunk (23 May 2012)

Oh hell Dave,it sounds as if you do have a problem but it could be lathe or chuck.

The Axminster catalogue has a diagram of the spec for a M33 x 3.5 spindle (T38). I would try measuring the lathe with some vernier callipers to see that it looks right. The thread pitch should be 3.5mm and the diameter of the threaded potion should be close to 33mm. 

That may help you establish if it's the lathe or the chuck.
HTH
Jon


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## wcndave (23 May 2012)

Thanks for speedy responses!



jpt":2m4428d4 said:


> The important bit is that the back of the chuck fits tight against the back of the register on the lathe. Looking at the video this doesnt happen and there is a small gap this is why you are getting wobble, make sure the thread of both the spindle and the chuck are clean and try it again and the two faces should meet as this is what makes the chuck run true.



What i don't get is why a back registration is what's required. Imagine a deliberately exaggerated example, of hanging a hula hoop on the lathe. it could be as tight against the back as you like, however it's not going to run true...

or do you mean that the chuck should cover the lathe stock, ie that the lathe goes inside more than just the threaded part?



jpt":2m4428d4 said:


> there are different ones for M33 x 3.5 lathes.


again slightly confused, as this must be "a size", is M33 different from 33? I ordered this online so any error is my fault, however i felt quite confident when I saw they had the 33 instead of the popular 8 and 16 versions...

The threaded portion is about 32.8mm, my calipers do not reach, however the deepest part, of the threaded portion of the chuck seems to be about 38mm

I now have 2 chucks for this lathe that do not fit, having ordered a different size a year ago when mistakenly looking at the UK version of the lathe online


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## myturn (23 May 2012)

That's not right, from the video you have a significant runout, as though the internal thread is not parallel to the chuck body.

I have had exactly the same problem with a Patriot from Toolpost so send it back and ask them to send one that works properly. When I did this the replacement came direct from Sorby.


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## chipmunk (23 May 2012)

The M in M33 just means metric thread and a pitch measured in mm rather than a TPI (teeth per inch).

The back registration makes sure that the chuck axis is parallel to the lathe bed but there is also an unthreaded register on the spindle behind the threaded part which should mates with a similar unthreaded part of the chuck before the thread begins when looking at the chuck from the back. In this case it should be 33mm diameter I think.

Jon


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## CHJ (23 May 2012)

I must say the clearance on the thread form seems excessive to my eyes but as said by others not a killer if the chuck rear collar and the spindle nose step mate correctly to align the chuck.

I suspect that the spindle nose is bottoming on the bottom of the chuck threaded socket. (I.E. To long for the recess)

Fitting a washer as suggested would overcome this but looking at the video I'm afraid it will hold the chuck away from the spindle nose location collar and you will be relying on the threads alone to align the chuck.
Not something I would like to put my money on not moving under load such as a catch with threads with so much clearance.


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## chipmunk (23 May 2012)

I agree with Chas and your measurements of the thread diameter on the lathe at 32.8mm suggest that it's the chuck that's at fault.

Mick's experience seems to suggest that Sorby have "form" on this issue.
Jon


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## wcndave (23 May 2012)

looking at the post i made when i got the 1" 8TPI (the other wrong chuck for this), the one thing that's missing is the picture of my spindle. However we seemed to come to the conclusion that it was a standard T38. Mine is 33. I have not seen anything advertised as T38, so how do I know which flavour of 33 I have got, and whether that is available.

in my case the register is about 40mm, and there is no recess in the chuck for that.

Mick, I think the runout is due to simple tightening against the back whilst having huge wobble due to the threads having lots of "wiggle room", so where i reach when it's tight is arbitrary. I can see how this is the case in my head, hard to explain, however the chuck being "properly made" is irrelevant at this time :-(


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## chipmunk (23 May 2012)

Hi Dave,
Looking at the video, your spindle seems to have a half-bead and a full bead between the reference face and the start of the threads. 

If these are 33mm diameter then they will act as a diameter reference (as unthreaded portion) for the chuck. It may be that the Sorby chuck's 33mm diameter register is somehow not compatible with this form of shaft?

Jon


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## CHJ (23 May 2012)

The above is an image from an earlier Axminster catalogue, the current one does not have some of the older forms listed.


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## wcndave (23 May 2012)

Trying to clarify,

from the axminster picture, i added a red line where the chuck is, this would make sense, that the register keeps the chuck central and true, and the back of the register does nothing really to align. I have put arrows to what i think is the "aligning factor"







In my case, the register is wider than the threads, so the chuck "stops" there, you have slop in the threads, and I am simply friction tightening against the big black part. nothign i can see in this picture keeps the chuck true...






So question is, what chuck do i need to ask sorby for?


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## wcndave (23 May 2012)

Chas just beat me to it with the catalogue page... i wish i'd never got this lathe, nothing but problems, an M2 taper light pull friction centre is the only thing i have bought that fits! And that's despite spending over £400 on accessories so far


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## jpt (23 May 2012)

There are several parts that make up a spindle as can be seen in the diagram below which comes from the Axminster catalogue.





3 = M33
5 = 3.5

These two measurements are common to all M33 x 3.5 spindles where the difference comes is in the other measurements. Unfortunately there is no standard for lathe spindles so manufacturers do their own thing. If you look at the Toolpost site on this page http://www.toolpost.co.uk/pages/Chucks_ ... _data.html you will see they list 5 different M33 x 3.5 references for different lathes. The difference is down to different manufacturers using different measurements for parts marked 1, 2 & 4 in the diagram above. If any of these measurements on your chuck dont match your lathe the chuck wont fit properly.

john


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## paulm (23 May 2012)

Try calling Peter at The Toolpost, he has an engineering background and is a good guy and will want to help rectify the situation I am sure.

Hope you get it sorted, must be very frustrating, especially with the extra delivery time !

Cheers, Paul


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## wcndave (23 May 2012)

mm, i went here, 



and just selected the 33 directly threaded, it does not state there are further options.

The page you put link for at toolpost doesn't specify which of the other measurements equate to which of the other types of chuck.... 
You think i am best to send them a picture / diagram with dimensions on?

Thanks Paul, one reason why my mitre problems thread was perhaps more vitriolic than normal, just had everything go wrong all day.... I'll have to get a job instead to take up my time ;-)


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## myturn (23 May 2012)

My Patriots wobble the same as yours when I thread them on. It is not until the back of the chuck hits the nose of the headstock (part 1 in your diagram) that it is secure and correctly located. So the register in my chuck bodies is not a tight fit over the register (part 2) on the headstock, but rather a loose fit.

Assuming that the larger diameter register on your headstock is true then the rear of the chuck should butt up to that in the same way. It is the two rear faces that make the friction contact that stops the chuck loosening during use. 

But speak to Peter Hemsley and he will sort you out.


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## flh801978 (23 May 2012)

A friend of mine had a graduate threaded patriot chuck that was significatly out sorby swapped it over with no quible


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## CHJ (23 May 2012)

Dave, with reference to your sketch no. 1.

The chuck should align on the collar (2) as you have drawn but pull up tight to the shoulder (1) and not bottom in the thread socket at (3)

The transition between (1) and (2) on the spindle nose should be machined at a perfect right angle and is the basis for true alignment. This then renders thread form discrepancies and in use damage as insignificant.

Some chucks have scroll mechanism exposure at (3) so clearance is essential.


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## wcndave (23 May 2012)

Ok, in the shop with feeler gauges and a ruler now. 

Assuming my second picture with the black block is how it should be, when it's fully tightened there is a gap between chuck and "black blob". .2mm smallest and 0.65 largest. The coved register between threads and black block is 33.89 at widest part. The chuck had internal smooth pre threaded part of 33.93.

So even were I able to get it tightened at the back with zero clearance all around, nothing is going to centralise the chuck. Hence my feeling that either the threads or register should offer a tight fit?


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## wcndave (23 May 2012)

CHJ":9e3vg9yq said:


> Dave, with reference to your sketch no. 1.
> 
> The chuck should align on the collar (2) as you have drawn but pull up tight to the shoulder (1) and not bottom in the thread socket at (3)
> 
> ...


So I do have clearance at 3, however still fail to see how the difference in register and internal chuck diameters means I can have a centred chuck. Even so,I cannot get the chuck to sit flat against shoulder (1)


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## 12345Peter (23 May 2012)

I have a Patriot chuck bought with an insert 24mm x 3, the chuck fitted well to the register, but had a pronounced wobble. I have just bought a Union Graduate that came with a Patriot and instead of a direct threaded chuck of 1 1/2 x 6 it came with an exsert that fitted to the headstock spindle and the chuck screwed onto that. There was no wobble that I could see, so I put my other patriot on it and that has a wobble, albeit not as much as when on the other lathe. When I have time I am sending it back.


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## wcndave (23 May 2012)

Further attempts show that the wriggle room means I can move through the right setting until the last turn, which pulls the chuck tight against the headstock at an angle. I can feel it forcing the angle. So either the depth of register is to great and I just hit the threaded part if the chuck too soon, or one is not machined right. I have put the supplied 10 cm faceplate on and that runs true, so next port of call must be toolpost I think. Thanks so much for all your input so far!


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## CHJ (23 May 2012)

The above is the ideal location areas so that the thread does not have an influence other than holding the chuck against the spindle face.


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## myturn (23 May 2012)

I've been out and taken some measurements. All my chucks are M33x3.5mm, so-called "German" type.

Conclusion:

The VM100 chuck is made to much finer tolerances. I have 4 of them and they are all consistent and as true as I could ask of a woodturning chuck. Two of them are direct-threaded and two have inserts but they are all as accurate as one another. 

The Patriots (of which I have 3) are a lot less consistent, the one I used here is the most accurate, they all exhibit significantly more runout than the VM100s. They are all direct threaded. I had one exchanged that was wildly out and quite unacceptable. These 3 are acceptable but reverse-mounting on them still introduces some wobble on the wood despite taking great care in sizing spigot or recess.
You may notice I have machined the rear of the chuck to take a Vicmarc lock-ring, that is not standard on the Patriot.

Don't expect perfection from the Patriot !
But don't accept wild inaccuracies either.


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## CHJ (23 May 2012)

Looks like your 25 thou. min. clearance on the collar radius (50thou on diameter) means that the patriot is relying on the thread form to hold it central.
Not very significant for a lot of jobs but a real pain if you get a slight catch that moves the chuck a fraction or wish to reverse an item when the alignment will be a bit hit and miss.


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## myturn (23 May 2012)

CHJ":27u1jme6 said:


> Looks like your 25 thou. min. clearance on the collar radius (50thou on diameter) means that the patriot is relying on the thread form to hold it central.
> Not very significant for a lot of jobs but a real pain if you get a slight catch that moves the chuck a fraction or wish to reverse an item when the alignment will be a bit hit and miss.



Is that not normal then? 
Even the VM100's have play between the two register faces which is only eliminated once the rear face of the chuck is up against the headstock nose. Yet they run perfectly true and never move out of alignment during use, even in reverse rotation.


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## boysie39 (23 May 2012)

I feel sorry for anybody with this problem re chucks .I had this problem with a lathe I had some years ago .
I got a direct thread chuck with the lathe when I wanted another chuck some time later I could only get one with an insert, thats when my problems started . Even now if I were to buy a chuck it would be supplied with an insert .
I have four chucks 2 Supernovas an Axminster K 10 and a Versachuck from The Toolpost. My go to chucks are direct thhread Nova and Axi. K 10 other two are for rough work .
Mike ,has a point about VM chucks everybody around swears by them ,more expensive but you get what you pay for.
Sorry Dave I know this wont help you with your problem ,but if you have a dedicated spindel thread why cant you buy a dedicated chuck to fit that thread , the answer is greed they sell you a insert and get another few quid out of the punter .
If it were possible I would send the lot back lathe and chucks .


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## CHJ (23 May 2012)

myturn":31dsybtl said:


> CHJ":31dsybtl said:
> 
> 
> > Looks like your 25 thou. min. clearance on the collar radius (50thou on diameter) means that the patriot is relying on the thread form to hold it central.
> ...



Unfortunately it becomes the norm because the lathe manufactures and the chuck manufactures don't hold tight enough to the specifications, erring on extra clearance rather than risk binding. Why else would it be in the design of a wood lathe spindle nose if it was not there to provide as good an alignment as possible. Given that it is not possible to machine a chuck register in situ as you would normally do on a metal working lathe.

Admittedly works fine for most woodturning as long as both lathe thread and chuck thread are good. Get one of them made at the lower end of the quality spectrum and we see folks having lots of aggro.

I have poolwood that has a no longer catered for spindle nose collar diameter. (see the diferences TO2 -TO2P)
My main user Axy precision chuck and faceplates etc. are of an age that they have the correct back plate and I have spares, and can turn my own if necessary.
My 125mm Axy chuck does not have the correct collar register and relies on the thread angle for centralizing but is well made and a reasonably close tolerance thread and does not give me any problems in use as long as I make sure the threads are clear of debris.

Another (unknown by me as to make) chuck I have does not have a suitable register but a slim line stepped adaptor collar takes care of keeping it true.


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## cambournepete (23 May 2012)

I tested one of my Stronghold chucks and there was very little wobble once it was screwed on a couple of turns and none at all when screwed on completely.
My Sorby eccentric chuck is a much looser fit, although it doesn't wobble when screwed on properly.


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## wcndave (23 May 2012)

boysie39":dkj6zcr8 said:


> Sorry Dave I know this wont help you with your problem ,but if you have a dedicated spindel thread why cant you buy a dedicated chuck to fit that thread , the answer is greed they sell you a insert and get another few quid out of the punter .
> If it were possible I would send the lot back lathe and chucks .



Well, i) the chuck I bought is dedicated insert to match the lathe to avoid issues of adaptors / inserts, and ii) i thought the sorby was sort of the rolls royce of chucks. if £160 does not buy one a decent chuck with just the one set of jaws included, then one's looking at a mortgage to get a decent lathe and chuck set + various jaws and bits and pieces...

I will ask toolpost what they think, but again, amazing response from my friends on the forum, thank you all!!


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## Noggsy (24 May 2012)

I'm lucky in that I don't have any issues with the chucks that I have (K10, K8 and Multistar), but I have still read this entire thread, because this is what I love about this site...people trying to help and being interesting and informative whilst doing so. Nice one to all involved, I've learned things which may help me in the future and enjoyed the usual banter.


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## cambournepete (24 May 2012)

wcndave":1cmflv3s said:


> I will ask toolpost what they think...


It's the Toolpost show tomorrow and Saturday, so you might not get a very quick response this weekend.


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## paulm (24 May 2012)

Thanks for mentioning that Pete, I might make a trip over there tomorrow. 

Would have missed it, yet again, as they don't seem to have any email distribution list or mailshots, and as I don't bother with the mags these days I never know they are on unless I happen by the website......

Sorry for the hijack Dave !

Cheers, Paul


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## wcndave (24 May 2012)

Thought a close up of the lathe thread might help.

I have all the dimensions, however left in the workshop, doh!


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## CHJ (24 May 2012)

Looks as though the locating collar is just fractionally greater diameter than the thread.

I believe the grove in the locating collar is to allow a chuck securing grub screw to engage without causing any location disrupting burrs.
Why one would do that on a lathe that does not have a reverse facility as far as I know is a bit of a mystery unless the component is common across differing lathe models.

The spindle nose has a Tomy bar or C spanner hole to aid in removing faceplates etc.


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## wcndave (24 May 2012)

Yes, I don't have a c spanner that goes with this. I was wondering if the threads in the chuck were just touching the locating collar, causing it to twist at the last moment. however having taking some rough measurements it seems there should be room..


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## myturn (24 May 2012)

referring back to a previous post you said....



wcndave":1kbx1u3b said:


> Assuming my second picture with the black block is how it should be, when it's fully tightened there is a gap between chuck and "black blob". .2mm smallest and 0.65 largest. The coved register between threads and black block is 33.89 at widest part. The chuck had internal smooth pre threaded part of 33.93.



If as you say there is a gap between the rear of the chuck and the vertical face of the headstock nose (the black blob) the chuck will not be held in place nor will it be held straight. It would seem, as I believe someone has already mentioned, that the nose thread is bottoming out in the chuck.
To verify this put some paint on the inside face of the end of the threaded part of the chuck and test-fit to see if any paint comes off on the headstock nose.

One possible remedy is to file/grind a bit off the end of the headstock nose. (hammer) 
Then, assuming the chuck is correctly machined, it should tighten up flat against the "black blob".


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## wcndave (24 May 2012)

thanks for the advice, i have double checked and it's not bottoming out, however the register of the chuck may be slightly shorter than what chas called the locating collar, by just a hair... can't really tell...


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## cambournepete (24 May 2012)

Try putting a sheet of metal between the chuck and the shoulder when you screw it on.
When screwed on tight there should be no wobble.
A suitable washer would be best, but you're almost bound to have something you can try.
If all else fails thin MDF or even thick cardboard would do as a test.

Someone on the forum made me a washer for my Sorby eccentric chuck because it bottomed out and now it works fine.


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## cambournepete (24 May 2012)

CHJ":2pnj2ler said:


> I believe the grove in the locating collar is to allow a chuck securing grub screw to engage without causing any location disrupting burrs.
> Why one would do that on a lathe that does not have a reverse facility as far as I know is a bit of a mystery unless the component is common across differing lathe models.


Because if you stop the lathe too quickly there is a danger of a heavy item spinning off.


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## dickm (24 May 2012)

FWIW, the Myford Mystro has a very similar arrangement to the pic of the Sheppach, although the register surfaces are bigger. From experience making an adaptor to fit a Bonham chuck to the Mystro (cheapskate!) getting the internal and external registers right is absolutely vital; the threaded parts are just there to hold things against the registers, not to give any precise location. 

That is, exactly what Chas has said. And he's right about heavy things unscrewing - guess who "forgets" to tighten up the grub screws into the groove  ?


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## wcndave (31 May 2012)

Just wanted to update that Peter from toolpost has been working with me on this every day, and been extremely helpful in every way.

We think that possibly the lathe register is just slightly too long, < 1mm perhaps, so the chuck does not go all the way on.

Getting a replacement body. If that doesn't work, I'll try a decent lathe!

+2 for good customer service from Toolpost


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## CHJ (31 May 2012)

wcndave":1cl1u4kn said:


> ........We think that possibly the lathe register is just slightly too long, < 1mm perhaps, so the chuck does not go all the way on.
> .....


If that is the case, it would be a simple matter to make up a packing/shim washer to sort that out, we just need to know the diameter of the spindle collar and how thick you need it to be.


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