Bowls can be turned from a round log cut to length or from a log split down the middle. What are the advantages or issues with each approach.—Anon
Claude Dupuis replies: Wood will always split at the pith. Best to split the log in two and get rid of it.
Peter James replies: Bowls turned from a round are basically a hollow spindle. Because the grain is not changing every 90° the grain pattern is circular around the bowl. Turning the outside is fairly easy like turning a spindle, but turning the inside is more difficult because it is all end-grain. Bows turned this way will shrink fairly evenly with limited distortion. One problem with this method is dealing with the pith in the center of the log. This is the soft center at the very center. One method is to remove it and replace it with a contrasting insert. Turning bowls from rounds is not the common method, but it is a method used to turn lidded boxes, hollow forms (wooden vases), and lampshades.
Bowls turned from a “half” section are more common. Because the grain is changing every 90° there are challenges dealing with tear-out, but proper technique and sharp tools can overcome this. Bowls can be turned with the bark side being the outside or ˝natural edge˝ with the bark side being the inside. Shrinkage is not even around the bowl with much greater shrinkage from the sides of the log than from the ends.
If round, not oval, bowls are wanted, you can start with either a dry blank or use the twice turned method. A twice turned bowl is roughed out and then allowed to dry under controlled conditions. After the desired moisture content is reached, the bowl is then remounted and turned to the final shape. A once turned bowl from a green wood blank will yield bowl that is noticeably warped or distorted. Sometimes this is a desirable feature and is used such as when turning wooden hats.