Walnut Bowl Problems

I am turning a bowl (about 6" in diameter by about 6" deep, side grain) from green Black Walnut. I have shaped the exterior of the bowl. When I started to power sand, I noticed that the outside of the bowl had several concentric ripples. These ripples are a bit too deep to remove by power sanding, but have eluded removal with a bowl gouge or scraper. I have not hollowed the bowl yet, so it shouldn't be moving too much.

I have tried taking a very fine cut with a sharp bowl gouge, but the new surface had just as many ripples. What is going on here? I'm pretty new to green wood turning. Do I just need to rough the bowl and let it dry for a couple of weeks before I proceed? Any suggestions will be much appreciated. Thanks.

Barry

Reply to
Barry N. Turner
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Barry, It sounds to me like you may be getting a harmonic vibration from the wood, causing the ripples. Try varying the speed up or down and see if it helps. Harmonic vibration results from imbalance and just the right speed. If you slow it down or speed it up so the harmonic goes away it may do the trick.

-Jim Gott- San Jose, CA

Reply to
Jim Gott

"Jim Gott" skrev i melding news: snipped-for-privacy@mb-m25.aol.com...

appreciated.

I agree absolutely with the vibe-thing.

But: The wood being green, it is already drying as you work with it. So, it will slightly move and warp as you work, and you will never find the good finish.

If you manage to finish it anyway, you will see it warp out of shape as it dries further.

Rough the bowl to half-inch thickness or slightly more, leave material for holding, inside and out, let dry thoroughly, finish.

Bjarte

Reply to
Bjarte Runderheim

Immediately plunge it into LDD and let it soak for a half a day. Remove, drip dry, wipe with shop towel, remount and start turning. That ought to take care of any potential cracking or warping. I am just wondering if you might not be having problems between softer grain wood and harder grain. The softer comes out easier and can leave a ripple effect. This was discussed quite a few posts ago. The considered opinion was that it wasn't from harmonic vibrations, but from the variation in softness between the grains.

Reply to
Leif Thorvaldson

Another thing you might do is rub in a little of your finish in the problem area and it will change the cutting properties.

Reply to
Derek Hartzell

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