Chuck insert does not run true

[Herbert Flower]

I recently purchased an 1 1/4"-8 insert (Nova, supplied by Amazon) for one of my G3 chucks to use it on a newly acquired lathe. That chuck has performed well on a smaller lathe (w/1"-8 insert) for some time. With the new insert installed, the chuck does not run true (actually wobbles).

Since the same chuck runs true (on the new lathe) using the original 1"-8 insert and a spindle adapter, and the face plate supplied with the new lathe runs perfectly true as well, I'm thinking the new 1 1/4"-8 adapter is the issue.

Has anyone had a similar experience with an insert? Am I possibly missing something?

Thanks for your thoughts.

[Bob Bouis]

You probably did already, but double check to make sure it's seated all the way down. Maybe loosen the set screw, mount the adapter on the lathe, and use the spindle lock to snug it down.

[Roger Chandler]

Good advice supplied by Bob......sometimes they just need some more of the insert seated into the chuck body, but make sure any screws are not interfering, and maybe a drop or two of lubricant can also help seat it all the way to the bottom. If you get it seated to the bottom and it wobbles, then the insert is defective, and should be replaced. Amazon will send you return instructions and send another insert.

[Sid Matheny]

Are you sure the insert is made by Nova? There are some others made that are not Nova that have a history of run out.

[Al Wasser]

I had two Nova chucks that did not visually run true. One I changed the insert and now runs true. The other, a G-3 did not run true after two inserts and I was able to get it replaced.

[Michael Mills]

The only problem I have had with one (out of 7) is there was a very small shard of metal which kept it from seating properly. Is it possible some type of derbis fell into it while swapping the inserts? I would take the insert out, go around the inside with a q-tip damped with oil and see if it picks anything up. Bob is correct in that sometimes it takes more pressure than you would think to seat the insert; I usually hold it by the hex and use something in the jaws to make sure it is tight. The mating of the end of the insert and the interior of the jaws is where the power transfer occurs.
Woodcraft is the only place I know that sell a knockoff; a real Nova will come in a small red box.

[Terry Vaughan]

I don't know that chuck, but check that the insert is meeting the register on the spindle nose when tight, and the chuck body is meeting the register on the insert. Sometimes the dimensions of what is nominally the same thread vary slightly. If in doubt, you could use an indicator to make sure the spindle nose register is running true, then that the insert is running true without the chuck. As others said, make sure the insert is screwed fully into the chuck. I use a bit of thread lock to stop the insert staying on the spindle when the chuck is taken off.

[Herbert Flower]

Thanks to all for your thoughts and advice. The insert was replaced and the problem resolved.