WOBBLING

[Drcal]

Last week I turned a confetti lamp (oil lamp) using a spindle 3X3" by 4.5" long. I started BC and turned a tenon and mounted the piece on my Super Nova. I then drilled a hole (1.5" diameter)for the small glass vial for the oil, I turned the piece to shape, sanded it and finished it.
I then mounted it onto my Nova Midi Chuck in the expanding mode, using the hole I drilled for the vial. I do this to remove the tenon and clean up the bottom. When I do this, the piece does not run true. It wobbles. If I run it at 1800 rpm it is ok and wobbles minimally but at slower speed is wobbles badly.
I switch chucks in the middle of my turning because I have dedicated chucks- one with 50mm jaws and one with 25 mm jaws. My lathe is perfectly aligned and the chucks work beautifully on other pieces. I have the piece mounted on the Midi real snug and butted against the face of the chuck with a little cardboard between to protect the already finished top of the oil lamp. This is the third time this has happened with oil lamps.
Any insights??? Any advice would be really appreciated.
Carmen

 

[nativewooder]

If you purchased the wood at a store it is green and has warped. If you know for certain the wood is seasoned and dry, what I would do is use the tool rest to help make sure the piece is centered by tapping lightly on the edge to make it run true. Also, you could bring up the tail stock as there should be a mark noting the exact center of the tenon. With the center of the tail stock in place, if there is any wobble, then the wood has warped. If this is the case, then re-turn the tenon to make it round again, and see if there is enough wood to return the lamp. Good Luck! And remember the standard rules of woodturning: #1. There are no hard and fast rules. #2. Refer to rule #1.:biggrin:

 

[Craftdiggity]

If the hole was not dead center, you would get a little wobble. Drilling on the lathe may be the most accurate, but it is not always right on. I would drill the hole, then mount it in the expanding chuck to true up, and then turn the tenon. This way everything is trued up to the hole and you should not have any other problems with wobble. You can then mount the tenon in the chuck and turn away. When you are done, mount in the expanding jaws and turn the tenon away and you ought to be right on.

If that doesn't work, I would agree with Barry's post. The wood is likely green.