Chuck wobble

[PaulB]

Can anyone help? I am trying to cure a wobble on my chuck. I have two chucks, both made by Nova.
They have each been supplied with an insert. The one I bought with the lathe was old and well used but seemed OK at first until I turned a piece and then reversed it in the chuck to find it was off centre, it didn't make any difference to the situation if I rotated the workpiece in the chuck to re-centre it. After investigating the setup deeper I noticed the chuck insert was registering on the spindle collar OK but the chuck was nowhere near what I consider to be its registration surface on the insert. Instead the chuck is bottoming out on the nose of the insert. Looking at BOTH chucks the I have the same problem, just the new chuck seems to run straighter. Its driving me NUTS (hammer) (hammer) (hammer) (hammer) . Where should the chuck register??????? :x :x :x :x

 

[CHJ]

….. Looking at BOTH chucks the I have the same problem, just the new chuck seems to run straighter. Its driving me NUTS (hammer) (hammer) (hammer) (hammer) . Where should the chuck register??????? :x :x :x :x

Without actually studying the items my initial reaction is that the adaptor insert should register with the chuck register.

Sounds as if the inserts are too long and bottoming against the chuck internals, thus just relying on how they ride on the thread forms.

I would suggest you shorten the nose of one of the inserts with a file or grinder so that the insert fully engages withe chuck body and see if that improves the situation.

 

[PaulB]

Thank you. I will try your suggestion at the earliest opportunity and let you know the result.

 

[hawkeyefxr]

I had the exact same problem on a new Record chuck. Luckily i gad a dial indicator so could check the run out. I was 0.015 on an inch, a mile out !!.
Record sent me a replacement, it was not perfect it was 0.004 out. Having said that wood lathes are not engineering lathes.

 

[PaulB]

Thank you all! I cured the problem. I replaced the insert for a new one from Nova. The runout on the spindle was negligible, the old insert, once fitted was threaded on the wobble being 20 thou out in opposite directions end to end - so a total of 40 thou!
For EVERYONES reference : the insert registers on its nose inside the chuck then registers on the spindle flange on the opposite end - so sayeth Nova!
Well all I know is that everything is running true now, so no need to mod the new insert at all.

Thanks again