Est. 1998 — 27 years of woodworking knowledge
Green Hackberry
Tug Fork Bob
>I have read that rough turning a green bowl to a wall thickness of 10% of the diameter will allow clean-up to round after it dries. However, I finish turned a green hackberry bowl and allowed it to distort as it pleased. Final size: 7-5/8 wide x 9 long. Would it have changed this much if I had rough turned it then let it dry? (I tried to post a picture, but the file was too large & I can't seem to shrink it down)
Bob Achenbach
Re: Green Hackberry
Brad Vietje
>Bob,
I'm a little surprised you haven't gotten any responses so far.
I live up north, where Hackberry doesn't grow, but some woods, such as Beech and Apple move quite a bit, so I usually suggest leaving the rough-out 10% plus the desired final thickness for these woods.
Then there's reaction wood, which moves even more than usual. Reaction wood occurs when the pith is well off center, and the growth rings are much closer together on one side than the other. This occurs when a tree or branch leans at a significant angle, and the wood is in tension on top, and compression on the bottom. If you use the wood on the 'big' side, it will move and shrink a lot more than wood from a vertical tree with the pith in the middle.
Are you measuring your green-turned bowl at the same height ? For example, a natural edge bowl can have an oval profile even if twice turned and completely round -- just an optical ilusion due to the varying height of the rim. Might this be affecting your measurement ?
Safe Spinning,
Brad Vietje
Thetford, VT