Axminster Precision Chuck Runout

[RichardG]

I’m not having much luck with my Record Lathe, having improved the vibration with a new bearing I wanted to use the Axminster Precision Chuck that came with it only to discover that it has a huge wobble. This is the Chuck.



I removed the backplate from the Axminster chuck which I believe was sold separately to adapt the Chuck to fit different lathes and then checked the runout. Unfortunately I have no way of measuring this but I took a slow motion video.



To compare I fitted a record pin chuck that extends forward by about 125mm so should exaggerate any run out and it looks good so I think the lathe is OK. Is this a fair assumption?



I’ve double checked the the faces are all clean so I can only think this must have been manufactured poorly, shame it says made in England. Is there anything I can do?

 

[CHJ]

Does the ISO backplate on its own run true when mounted on the spindle?
Does the ISO spigot run true and is it a good fit in the chuck body?

 

[RichardG]

That video only shows the backplate. I removed the chuck to eliminate it.

The spigot is a good fit to the chuck. It can be rotated to 3 positions which I have now tried and used a set of feeler gauges to measure the run out in each position. It was the same in each case. I measured 12 Thou or 0.3mm at end of the chuck body.

So can I assume the Chuck body is ok and it’s the backplate with the issue?

 

[RichardG]

Using my trusty feeler gauges I have measured 10 thou runout at the face of the backplate and <1.5 thou on the edge. At the end of the Chuck this has increased to 12 thou and at the end of the screw mount it’s got a proper jiggle on.

 

[Duncan A]

Have any of the faces been knocked, causing a (hard-to-spot) raised area?.
Check with a straightedge on the face of the backplate that sits on the register.
Duncan

 

[CHJ]

What is your spindle thread, (someone close may have a spare you could try) and does the backplate register match the spindle register? if not you may be relying on the thread form alone to align and any spalling or debris on the thread form may be tipping the backplate.

Spindle Nose dimensions (Register dimensions)

 

[RichardG]

Have any of the faces been knocked, causing a (hard-to-spot) raised area?.
Check with a straightedge on the face of the backplate that sits on the register.
Duncan

Thanks for the suggestion, I’ll double check this today.

What is your spindle thread, (someone close may have a spare you could try) and does the backplate register match the spindle register? if not you may be relying on the thread form alone to align and any spalling or debris on the thread form may be tipping the backplate.
Spindle Nose dimensions (Register dimensions)

Spindle nose is 3/4 by 16 tpi, so if anyone does have a similar plate and would be willing to try mine or loan me theirs to try then that would be much appreciated.

I believe the Versa Chuck sold by the toolpost was a similar unit but going to see if they could help it seems they have gone out of business.

I don’t suppose anyone has an old Axminster catalogue with these chucks in? I was going to contact Axminster to see if they would be able to refurbish it or have any spare parts but it would be useful to have a part number of some reference.

 

[CHJ]

Would think that 3/4 by 16 tpi is on the lower limit on size for something as heavy as the Precision Chuck and may be in short supply.
Afraid I only have a 1" & a couple of 1/1/4" used to adapt my wood chucks for different lathes - (My wood lathe uses 1-1/2" .)

 

[Lignafera]

I also use an Axminster Precision Chuck, my chuck was made in Poland.
My backplate is 1/1/4", I agree with CHJ, 3/4" is rather small diameter for a very heavy chuck.

 

[RichardG]

The actual shaft/backplate of the lathe is 1/1/8” but the thread is 3/4”.

I‘ve checked over the chuck and all surfaces are flat and well mated so I‘m now convinced it’s been poorly manufactured.

I spun the lathe by hand and found the point with the maximum offset and then inserted a shim of 0.25mm between backplate and the lathe body. The chuck now runs true.

I know a model engineer who makes small scale model traction engines from scratch so I will see if he can skim the face for me.

 

[Inspector]

Ideally you should have a dial indicator or dial test indicator held by a magnetic base to check the runout. Perhaps your model engineering buddy could bring one over to help you diagnose it. Using feeler gauges works but limits what you can check. Does the spindle have a morse taper or is it solid? Checking just inside the taper would show if the spindle is bent assuming the taper and threads were machined concentrically. If it is good then your chuck adaptor plate is not properly machined and a good machinist could reface it using the spindle of your lathe to hold it. Would have to pull it from the headstock so he could turn it as a set.

Pete

 

[RichardG]

Thanks for this, there is a morse taper #1 so my friend may have something to measure in there. Typical, I’ve only just had the spindle out to replace a bearing! Oh well it will be good to get this fixed.

 

[clogs]

did it have run out before u changed the bearing....?

 

[RichardG]

No idea, I haven’t used the Chuck before and unfortunately the previous owner is no longer with us.

 

[Paul Hannaby]

I recently had a similar problem with a super precision chuck which seemed to have a wobble. I used a dial gauge and confirmed the run out (0.2mm in my case) was with the backplate (M33 in my case). I also measured the thickness of the backplate which varied by the same amount as I measured the runout so it was pretty conclusive the backplate was the problem.
I contacted Axminster but they weren't interested in doing anything about the problem as they no longer sell the backplates. Perhaps they had a duff batch?

Fortunately, I had a spare backplate and that cured the problem. I may take the faulty backplate to my local engineering shop to get it trued up properly but as I doubt if I will be buying more chucks - I think I have enough to see me out now!

I also have a spare 3/4" x 16tpi backplate if you need one!

 

[RichardG]

I also have a spare 3/4" x 16tpi backplate if you need one!

Thanks very much for the info and the offer of the back plate. I‘m hoping that I have now fixed mine but I’ll PM you if I need it.

I took my lathe spindle and the chuck over to my model engineer friend today. He spun it up on his Harrison lathe and confirmed that the backplate was in error, by about 10 thou, very close to your 0.2mm! He has now skimmed the backplate flat but I haven’t yet mounted it all back in my lathe to test. I’ll report back tomorrow.

Watching him mount the spindle was interesting, he placed the end bearing point in his chuck and then set up an intermediate roller support at the other end where the taper bearing sits. This was all zero‘d and meant that the spindle was being held exactly as it would be in the lathe. He then mounted the backplate and did the skim. Took him several hours to do.

Looking at the backplate he was fairly confident that it was made on a CNC lathe as it would be almost impossible to hand machine the error he was seeing.

fingers crossed.

 

[minilathe22]

I believe woodturning tools are not made to as high an accuracy as metal lathe tools, as even a badly out of true chuck can be used to produce round work, as long as you do it all in one go. I suspect many woodturners do not notice, or just put up with it. Also many woodturning projects that are not truly round will be "good enough" as they just need to look nice and do not need to be a precision fit into another component, unlike making parts on a metal lathe.

I have some tape wrapped around the bit before the thread, so that my chuck mounts centrally. Really should find a better solution!

 

[RichardG]

I can confirm the problem is now fixed. I can now take something out of the chuck and put it back in again with it still running true. Vibration has also reduced slightly.

I believe woodturning tools are not made to as high an accuracy as metal lathe tools, as even a badly out of true chuck can be used to produce round work, as long as you do it all in one go.

As a beginner I have been taking things out of the chuck to have a look but I can see it wouldn’t be an issue if you turn something in one go. Although if you turn a mounting point on the bottom of a bowl and then remount using that mounting point wouldn’t the bowl no longer run true?

Thanks to everyone for their insights, I can now focus on learning to turn again.

 

[Phil Pascoe]

It will be truer but they never remount in exactly the same plane, and if you finish the work in one hit the wood itself doesn't get the chance to move. It doesn't make a huge difference a lot of the time, but it can if you are doing segmented work, inlaying, fitting a lid etc. I have a large sycamore bowl that came full of something in a harvest festival - I didn't turn it - and I thought I'd try to refinish it. It has a rim some 12mm - 14mm wide, but I can't get a circle out of it.

 

[CHJ]

As a beginner I have been taking things out of the chuck to have a look

Removing a partly turned wood item out of the chuck and attempting to remount it accurately is worst case scenario.

Wood compresses as the jaws bite in, for 80% or more of wood species the wood will relax to a degree when released and even if the wood does not distort due to the difference in side/end-grain movement differential whilst off the chuck and go 'out of round' attempting to get it running true again invariably results in frustration.

If an item is anywhere near finished size then the worked surface, be it outer or inner needs to be completed and left alone, trying to go back to it afterwards, sometimes even within a few minutes will result in it being found 'out of round'.