Lathe Headstock Warn Threads For Robert Sorby Patriot Chuck

[Chisteve]

Hi first post

I'm Steve happily retired in Chichester West Sussex after working in Architectural Metalwork and Structural Steelwork for well over 40 years

I have a Union Jubilee lathe that I refurbished, put a new motor on and replaced the bearings etc all works fine now

The only problem encountered is when I put patriot Chuck on spindle it's not spinning true I have packed it, this helps a bit but not perfect I suppose I need a new spindle it’s perfect using centres

Any ideas ?   


 

[Twisted Trees]

Is the chuck fitting properly against the register plate?

[Bill21]

I can’t help but perhaps someone at you local club can?

http://www.forestofberewoodturners.com/index.html

[Wood spinner]

Does the Sorby chuck have a removable back plate ?
If you think its a chuck fault contact Sorby and ask if they can test it.

[Chisteve]

Hi thanks for the replies - I was not aware of the club nearby, handy for me as not heard of them before, I will check the chuck insert against the register plate, I have inserted a small packer there as noted above, it's helped a quite a bit but am going to investigate this area more and may adjust to suit

Whilst the chuck was second hand to me it appears to have had little use if any and as the above has made a difference I don't think there's a problem with the chuck     

[julcle]

Not sure what you mean by having packed it. Robert Sorby supply (or used to) a thread insert for the Patriot to fit the Harrison Jubilee and as said above this will sit on the collar of the spindle registering it flat and square. I think it's 1"x10 thread on this lathe.

[Duncan A]

If the threads are a loose fit and the spigot is a loose fit inside the chuck insert recess, the chuck may tighten up correctly onto the register but slightly off centre i.e. parallel to, but not on, the axis.
You say that centre drives in the spindle morse taper run true so the spindle is fine.
I have come across this in the past, and thought the chuck (Patriot) was the fault but it was not. It may be fixable by enlarging the spigot very slightly (tape of some sort?) or by buying a blank insert and having it machined to be a better fit on your lathe.
You could also remove and refit the existing insert just in case there's something going on there.
Duncan

[Chisteve]

it’s a little difficult to explain but I screw the insert into Chuck tighten and lock with grub screw and then screw it onto spindle then tighten it holding the spindle and using the insert spanner. Once on checked where it was out loosened the Chuck and placed a small plastic construction type packer say 1 mm between the back of insert and spindle flange to correct the chucks position a picture would explain much better but Lathe is around the corner in my workshop

[Bill21]

Curious, I’ve not seen an insert that needs a grub screw to hold it in the chuck. I’ve only had Axminster and RP chucks though.

[jay]

   Is it possible to fit the insert to the lathe and run a  dial test on its face or edge to see the run out ? It might isolate the problem

[Bill21]

Putting an indicator on the insert could be tricky.

https://www.oliverswoodturning.co.uk/product/patriot-chuck-thread-adaptors-2/

[jay]

   Looks like one could get a reading off the  register surface on the excert   more difficult with the other version . Makes me wonder what if the hex was chewed up making a burr . Would that distort the running

[Bill21]

Pictures of the spindle, chuck and thread adapter would help.

[Paul Hannaby]

Is the register on the chuck the same diameter as the register on the spindle? If not, the chuck won't run true...

[Bill21]

One of the chucks I bought for my current lathe (M33 x 3.5 spindle) had a screw in adapter that mated fine with the register on the spindle but the chuck still didn’t run perfectly true. Since that time I’d only ever consider a direct threaded chuck, or at least one with a backplate fitting.