Whether I am making a salad bowl or large hollow vessel, there is a lot involved beyond the actual turning. This page describes, in general, how make a wooden bowl and hollow vessel from a standing tree. All pieces are made with a chainsaw and a wood lathe with a few hand tools.
Turner Lumber…where do you get your wood?…
Material used for wood turning is different than that used in furniture making. For many projects, there is not lumber of sufficient thickness available at lumber dealers. Wood blanks are cut straight from the tree in large blocks, rather than slices as boards are. Therefor this wood usually “green” or undried.
I source and cut nearly all the wood that I use. Wood for turning is very easy find if you know where to look. Especially in North Carolina there is such abundance and diversity of trees. I work with over thirty species of trees, primarily hardwoods. Most of which have already fallen or been taken down due to damage, disease, storms, etc. Once a tree is felled, the trunk is cut into sections (bucking), just as if it were to be used for firewood.
Wood turning blanks for bowls vs hollows
This is a matter of wood selection really. I make hollow vessels from every part of the tree, anywhere is fair game. Utility pieces, however, need more stable defect free wood which is found in the trunk of the tree. A lot of interesting looking wood is found around defects. Consequently, those sections are good for decorative pieces and are not suitable for utility work.
Look out for the Pith Wood!
At this point a bucked section is cut down into multiple blanks. The main thing to note is the pith of the log (Figure 1). The pith is the most unstable part of the log and is where cracks start, so it has to be cut out. This is a typical way the log is sectioned into blanks. Here is a cut plan and some items that would be made from those blanks (figure 2).
Generally, I keep bowl blanks about 18″ long by 16″ wide by a depth ranging from 4″-8″. Additionally, this is the time to do some grading. Sections of the tree containing obvious cracks and defects are set aside for decorative items. It is important to keep utility pieces as defect-free as possible. Those defects will cause problems down the road in utility pieces.
When sawing blanks for hollows and urns I cut them at any size and I am a lot less stringent about eliminating defects (Figure 3). For decorative pieces, there is more flexibility to incorporate these types of characteristics. Decorative blanks that contain lots of worm holes or cracking get used for sculptural work. Those issues require a lot of labor to remedy for urn blanks and usually are not worth the time to do so.
How to keep wood from splitting while drying?
After the blanks are cut, I seal the ends of the bowl blanks with a green wax sealer to help prevent cracking. This product is called Anchorseal, and once waxed the blanks are stacked for later use. Any blank that is used for hollows or urns I seal all cut surfaces that have endgrain. Those wood blanks are more likely to have end grain exposure to more than two sides.
Waxed turning blanks are kept covered to prevent excess sun or water exposure. Although, there are exceptions for blanks that I am looking to spalt. I just leave them uncovered and let the elements work their magic. Those blanks do need to be covered up at some point or they will deteriorate to a point where they are unusable.
Time to do some wood turning…
Here is how I make a wooden bowl, the actual turning that is. The bowl blanks need to be cut into rounds on a bandsaw or chainsaw for balancing (Figure 4). They should be cut so they clear the bed of the lathe. A round bowl blank is mounted on the lathe, and turning begins.
Unless the tree has been felled for a long time (years) the wood is still “green”. This means its moisture content is still high and the wood is prone to movement as it dries. The bowl blank rounds are turned into a rough bowl shape, with the thickness being approximately 1/10 the diameter of the rim dimension. I core my bowl blanks yielding two or thee rough bowls per blank.
I mark rough wood bowls for date as well as species and completely seal the rough bowl with wax. (Figure 5). At this point, the rough bowls are moved into a less humid area to spend the next several months. Rough turning speeds up the drying time and allows the stresses in the wood to release, helping to prevent defects. I like to keep rough bowls stored for about a year so to dry out well.
The variation in drying time is impacted by how much water the wood had in it when it was gathered. A tree just felled will have much more water than one that has been down or dead. Species of tree also impacts the drying time; some woods hold on to water longer than others. Less humid climates also affect the drying rates, these areas require less time but can be prone to cracking as evaporation is much faster.
Once a bowl has dried, I remount it back on the lathe and turn it to its final shape and thickness. I sand the outside of the bowl before turning and sanding the inside. It’s common for some slight distortion when turning the final thickness. After the inside is turned and sanded a bowl is remounted and the bottom turned and sanded. The bowl is removed at this point and is finished with walnut oil or Danish oil depending on its function.
Want to make a Hollow Form?
I skip the roughing phase for hollow forms. When the walls are turned thin they dry much more quickly. Quickly being a couple weeks when the walls are around ¼” thick or less. Being as thin as they are, the hollow forms are much more elastic, so cracking is not a problem.
A vessel blank is mounted between centers on the wood lathe. This allows the tenon to be turned which will in turn allow the vessel to be mounted in a chuck. Once mounted in the chuck, the outside shape is formed first and sanded. The opening is established and a column is bored out to establish the inside bottom of the vessel. The inside material is then hollowed out so that the walls are around 1/8” to 3/16” thick. Once all the inside material is removed the hollow vessel is jam chucked so that the outside bottom of the vessel is turned and sanded.
I finish sand the bottom of the vessel and apply a seal coat of Danish oil. The hollow form is then put in a paper bag to rest for several of weeks. This resting allows time for the wood to dry and the stresses to reach equilibrium. Once the resting period has passed, they are signed, numbered, and the final coats of finish are applied.