pipemakersforum.com

Material wobbles in my spigot jaws. At first, if I kept loosening and retightening the stock in the jaws, it would magically be fine and spin perfectly. Over time, it got worse. Now, 99% of the time, the stock wobbles off center. I can't drill a piece of delrin on center and it's really annoying. How to fix this?

There's a couple things at play here.

The first is that you're using a 4-jaw chuck. While this can work, and does work in some cases, it's not the same as using a 3-jaw chuck. 4-jaw scroll chucks just don't center as well as 3-jaw chucks, and will always position the material slightly off-center.

Second, the spigot jaws are made of a pretty soft steel, and they will bend - making it difficult to get a good grip, let alone a precision grip, on rod stock. If even one of your jaws gets bent outward, your stock will wobble.

For a long time I used a oneway chuck with spigot jaws for rod stock work. I don't anymore, for both reasons above. I suspect that, if it used to hold securely, and now it doesn't, you've got a bent jaw or two.

--K

Well, that sucks. Thanks for the info.

I had that problem with my 4 jaw chuck I use for stems..........two of my jaws were loose tightened em up and haven't had a problem since

I use this chuck exclusively for rodstock and always have, maybe that helps?

You didn't mention the kind of lathe, I'm guessing a mini/midi wood lathe?

There is a thick, flat washer/spacer that goes over the spindle, behind the chuck. Not using that spacer can cause the condition you describe.