Thread: Help with chuck "wobble"...

Did you put the pin jaws on in the correct sequence.
Is the area under the jaws clean.
Are the jaws tight.
I don't know what else.

On the chuck insert, is there a locking bolt?
On the Vicmarc chucks the locking bolt is screwed in horizontally from the back of the insert and needs to be unscrewed before fitting the insert to the chuck.
Apart from what Dave said there is little more it can be - try refitting the stock jaws and see what that does.
Cheers
Paul

Try it without the spacer.

I'd lay odds on the jaws not correctly fitted. Remember they are number stamped with their locations.
A common trap (apparantly).

Originally Posted by soundman

I'd lay odds on the jaws not correctly fitted. ....

Nope he said... "Reassemble, except for the jaws, power up and... Strike 3!"

I'm gunna put my money on the spacer.

No payout for anyone yet.

I tried it without the spacer today and still no joy. I also tried it with a newer Nova Precision Midi and that chuck didn't wobble, even though 'tis slightly heavier. Although it doesn't solve the problem, it relieves my angst about the headstock bearings. [Phew!]

The thread insert is the next obvious culprit, but...

• It hasn't been removed from the chuck since being purchased way back when.
  
• The locking grubscrew actually needed a bit of persuasion to release, so it certainly wasn't loose.
  
• After careful inspection, (I used a jeweller's glass) both insert threads (inner & outer) appear undamaged & fit snugly to the relevant mating threads.
• Similarly, both the spindle & chuck body threads appear undamaged.
  
• Using a spare insert made no difference, the chuck still wobbles.

The only other thing it could be, that I can think of, is a warped chuck body. How this would happen is beyond me; the SWMBO admitted that the lathe was "borrowed" while I was away but I can't see how any misuse could warp the chuck without causing obvious damage to the lathe and/or tool-rest.

Has anyone ever encountered something like this? :confused:

Originally Posted by Skew ChiDAMN!!

....The only other thing it could be, that I can think of, is a warped chuck body. How this would happen is beyond me;

Did you leave it sitting on the dashboard in the sun?

Originally Posted by Skew ChiDAMN!!

....the SWMBO admitted that the lathe was "borrowed" while I was away .....

ARH-HUH!!!! That'll do it everytime... somebody else touched it & it got all bitter & twisted.

What was held in the chuck when it was " borrowed ". It may have been an irregular shaped piece of wood & a lot of pressure was placed on the jaws & scroll thread to hold it & this could have distorted the scroll thread & matching jaws. Threads are very powerful clamping mechanisms & can cause a lot of damage if overtightened.
That's my two bobs worth. Good luck.
Barry.

& what if the borrower opened it up too far & then did it up again with the jaws in the wrong scroll threads or even worse, what if the took it apart & put it back together all out of order? :confused:

Jeez Cliff, poor old Skew's probably had to take a couple of Bex & go for a good lie down after this lot eh?
Hopefully it's something really simple that we're all missing & will be a cost free fix ;-)
T.T F.N,
Barry

Originally Posted by Cliff Rogers

ARH-HUH!!!! That'll do it everytime... somebody else touched it & it got all bitter & twisted.

Nar, it's me that gets all bitter and twisted when someone else plays with my toys.


Just to clarify things, the entire chuck-body is running out of true, not just the jaws. Even if someone took a gas-axe to the scroll threads and mixed pin-jaws and 75mm jaws I doubt the resulting weight offset would mass enough to deviate the chuck. Not when I've had the same chuck mounted on my MC900 with an OOB load that walked the lathe a few feet w/out wobbling the chuck. That I noticed, anyway... I was probably more occupied with trying to avoid the lathe while hitting the off-switch at that particular moment.

Hmmm... metal fatigue? I'll look into that on the morrow...

I doubt 'twas the result of a OOB load anyway; this is on a Ledacraft mini-lathe I use for pens. It's not even bolted down. Any load that'd do that damage would result in the lathe flying across the room and there's no dings or blood-stains in the wall, ceiling or concrete. No new ones, at any rate.

I've given thought to how I'd deliberately make this happen and I always end up with the chuck mounted on a solid 1" rod and a 4lb sledgie...

A 4 lb sledge won't do much damage really but a ham fisted persom may well have created more damage trying to do something you and I wouldn't.

He still alive???

What were they trying to turn???

I've done a few crazy things and given myself some damage but never managed to achieve any damage to a machine ( even a MC900 ) - only myself

You should be able to determine where the damage is by making a few checks.

A thou or two in a bent headstock shaft won't be that obvious till you put the chuck on it. Try a centre in the morse taper and see if you get any runout.

FWIW

Jamie

Have you tried changing the insert. I imagine that would be easier to damage than the chuck. I think that the insert from the larger Nova will fit??????? if the larger nova works ok the it cannot be the lathe it has to be a problemwith the chuck.

Hope this helps - peter

Crikey Jack! :eek:
You'd have to be trying real hard to bend a whole chuck?
Have you stood it flat on its back & rotated it next to a ruler to check for true & run you calipers round it.
You've got us all fascinated now.
If it is bent, we'd all realy like to know how :confused:
cheers