Woodworker's Journal winter-2009, страница 12

Finished Green Turning

Turning as much legally

green, undried wood is about fun as a woodworker can have in a workshop.

by steve blenk

While most woodworkers are taught to avoid using green (unseasoned) wood, woodturners can grab a block right off the stump and go to town making shavings. Here are some tips to make green woodturning fun and to ensure that you get the best results from your experiments.

Freshly cut (green) wood with a high moisture content is, by nature, unstable. As it dries, it is prone to warp, check and generally do things that give woodworkers nightmares. The movement is caused by the cells

of the wood changing shape (shrinking) as the moisture leaves. Outer layers often dry faster than the inner ones. This uneven drying creates stresses in the wood, which cause checking. Left to itself, drying is a slow process, with thicker air-dried material often requiring years of seasoning. We kiln dry (KD) most lumber these days and, while this speeds the process, it can result in another set of problems. Wood can be "case hardened" (hard and dry outside, still wet inside), checked or fractured with "honeycomb cracks" (checking not

visible from the outside). It can also be over-kilned to the point it becomes prone to fracture with hidden stresses. The thicker the material, the less effective kiln drying generally becomes. KD wood is no fun to turn, either. It is hard on both the turner and the tools.

There are two ways to approach green woodturning. You can look at it as a step designed to speed the drying of bowl blanks to a fin-ishable form, or you can sculpt complete turnings in the green condition and let nature have her way. You can even give her a prod, as you will see.

Mount a 10" segment of tree limb or trunk between centers. Mount it off-center to avoid making the weaker pith part of your stem. Remember to raise a round nub to grab later in a chuck. Hidden knots or defects can create a problem as you turn.

12 finished green turning