Shrinkage of Wood Cylinders
Advice on drying wood cylinders with the cores drilled out. December 8, 2012
My son wants to make cylinders from 8" to 12" diameter green logs that are from 8" to 16" long. Woods like maple, cherry and walnut. He wants to turn the logs on the lathe to a 6" round billet, then drill a 5" hole through them, leaving a cylinder. What can he expect as far as movement and splitting? Also, what would be the best way to dry these cylinders?
(Sawing and Drying Forum)
You will have the least amount of trouble with the walnut, the most with cherry. You could expect something like 1/2" to 3/4" out of round after drying. If you go slow at the beginning with drying, you shouldn't lose too many to cracking, but if you turn them wet with thicker walls, then return when dry to make them round, you will get more cracking. Research what bowl turners do with wet wood. You'll find guys that submerge them in a tank of denatured alcohol to reduce the cracking. It's going to take a pretty good rig to drill a 5" hole, 16" deep. It takes a lot of horsepower to do that, even with a 3" hole. You'll need a spindle steady and really long boring bar. The bar is really going to vibrate at that depth.
From Professor Gene Wengert, forum technical advisor:
Because the core of the round is removed, the wood will have room to shrink. Expect the diameter to decrease by 8% on the average. If the cylinder is centered with the growth rings, you should get uniform shrinkage and the pieces will not oval much at all, unless there are crooked trees or logs, knots, or reaction wood or if off center.
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