Getting work centred in chuck

[JackWilliam]

Another problem-

I am trying to get 50mm diameter nylon centred in my 3 inch, 3 jaw chuck.

I cant get it centred, as soon as I start to rotate the chuck I can see the piece wobbling, not on a straight axis. There is no way of tuning each jaw independently and I have fiddled about for ages trying different things, cant get it to work though.

There is only around 10mm of chuck jaw in contact with the work piece. This seems as though it may be the reason.

But how can I solve this problem?

Thanks
Jack

[knudsen]

Can you drill it and use a center on the tail stock?

[M250cnc]

Another problem-

I am trying to get 50mm diameter nylon centred in my 3 inch, 3 jaw chuck.

I cant get it centred, as soon as I start to rotate the chuck I can see the piece wobbling, not on a straight axis. There is no way of tuning each jaw independently and I have fiddled about for ages trying different things, cant get it to work though.

There is only around 10mm of chuck jaw in contact with the work piece. This seems as though it may be the reason.

But how can I solve this problem?

Thanks
Jack

You are right, 10mm is too small an amount.

You could tap the billet while the lathe is running and get it running true, but it could go out of true just as easy, unless drilling.

So its dangerous IMHO

Its doable using custom machined soft jaws but a lot of trouble.

Sent from my HTC Desire using Tapatalk

[alfiius289]

Look up 'popnstart' on YouTube. He has a quick and easy way to center stock in a chuck. Other than that, you are looking at a lot of troubleshooting and grinding hardened jaws on the chuck to get the run-out down. I made several of the centering tools and mounted them on my 4-way tool posts. Misalignment between the tailstock and headstock is another story.
Regards, Al

[Fastest1]

Check this guy out!
[nomedia="http://www.youtube.com/watch?v=cASpZUQ80pI"]YouTube - Retifying the chuck of Sherline lathe "HD"[/nomedia]
He is correcting the misalignment of some chuck jaws. Though it is a Sherline the technique is the same. To do this you would need to be pretty knowledgable in alignment issues. This guy gets it!

[03ram2wd]

video.soyof.com

[eartaker]

Nice I like the bearing idea. I'm going to make one of those.

[chronic]

Just double checking, you have the number chuck jaws in their proper slots?

Is the scroll clean?

What I would do if the jaws are messed up that bad, is throw a dial on your work piece, then just shim it so the piece runs fairly true next to the chuck. Then tap your piece true furthest from the chuck.