Barry - it's not the chuck.
several others have posted valid ideas as to cause, but you will
almost always get resonance at some RPM with a bowl because you are
making a bell and gee, bells ring.

I disagree with teh 40% rule - I've turned a platter that was about 24
inches across (asymetric, that's the long dimension) using a tennon
that was a lot less than 10 inches (I'd say about 3 inches), no
problems with the tennon, though I was unusually careful to not have
the wings smack me - I'm not particularly fond of splattering my own
blood on my nice black lathe.

As Leo suggested, you can be patient and let it dry. Or you can do
what I do and cut to finished dimensions in one pass and then deal
with any distortion bycalling it a "feature" - in that case, turn thin
(1/4 inch or so) and declare victory.

To cut and avoid the vibration, sharp tools, and a light touch, adjust
RPM, and thin from the rim down in about 1/2 inch to 1 inch steps -
more vibrational energy is transmitted for cuts near the rim, so keep
the mass inthe bowl as you thin the rim.

On Sun, 19 Mar 2006 21:17:05 -0700, william kossack
wrote:

a few things
- reverse the bowl against your chuck holding it in place with the
tailstock.

- True up the tenon or cut a new larger one. I bet you have enough wood
with the thickness but if all you have is the 50mm jaws on the super
nova you may not. With larger bowls I use the power grip jaws.

- While it is reversed also round of the outside of the bowl so when you
put the tenon back on the chuck it will be more balanced.

- Look for cracks. I find that little cracks in the wood can cause more
vibration resonance. You can almost tell that something is not right
when your bowl startes to sing. You can expect something to come flying off

- How fast are turning the bowl? Always start slow.

- Test your nova chuck by spinning it without anything mounted.

I've recently started putting my roughed turnings in a scale and putting
the information into excel so I can plot the drying rate and know when
it is dry.

Barry N. Turner wrote:
Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com
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