Turning Archive 2004

What am I doing wrong?

Brad Homman
>I have had several occasions roughing-out bowls where I encounter vibration and or wobble that doesn’t “turn out” as the blank is brought into round. When this happens, the vibration may continue after reversing the blank and attaching it in a chuck. I’ll outline my procedure, hopefully someone will be able to tell me what I’m doing wrong. 1) Attach the “flat side” of the blank to a face plate, using a 6” plate if the blank is big enough, attaching with four 1.5” hex head sheet metal screws. 2) Turn the outside to shape, forming a tenon to hold in the chuck when reversing to turn the inside. I always make sure to turn a flat face on the bottom of the bowl for the chuck jaws to seat against, and to true the tenon, forming a slight taper to match the shape of the chuck jaws. 3) After turning the outside, remove the faceplate, secure the blank in the chuck and turn the inside.

Usually everything works just fine, even when the blank is out of balance initially, as soon as everything is trued up the vibration diminishes and it’s smooth sailing to completion. ‘But there have been several occasions where when I start with an out of balance blank, using the procedure outlined, that the vibration continues even after bringing the bowl “into round” and after reversing it in the chuck. I always check to make sure that the face plate is securely attached to the blank. I’m turning on a new Jet 1442 so I don’t think the problem has anything to do with play in the headstock. I think I’m doing something wrong in attaching the blank, but I can’t figure what, can someone offer any suggestions on how to eliminate this problem?

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