There are many different approaches to making bowls. Most of the wood that I utilize is “green” or wet wood, i.e. wood that has not been dried and generally contains nearly 50% water. As green wood dries, it will shrink and warp in several directions. Each species of wood will act significantly different requiring the process to be adjusted to fit that species.
I will attempt to summarize the bowl making process that I use.
Wood for a bowl can come from many sources. As I stated above, I tend to use green wood that is fairly easy to find at a reasonable cost or free. Many times I raid my firewood pile!
The wood must then be prepared for the lathe by creating what turners call a bowl blank.
This blank was put on the band saw and had the corners removed to aid in the turning process. Note the blank orientation on the lathe
In this view (top) you are looking at what I will make the bottom of this bowl.
This blank is attached to the lathe using a 4 jaw scroll chuck with a screw bit. I will then turn the bowl and form the general shape of the bowl and the tenon used to grip the blank with the 4 jaw chuck. The tenon is the small, round shape at the bottom of the bowl blank.
The bowl blank is then turned around and inserted into the 4 jaw chuck This chuck is used to tightly hold the blank for the final roughing out process. As a general rule of thumb, the tenon width should equal 40% of the diameter of the bowl blank.
Once in the 4 jaw chuck, the inside of the bowl is hollowed out. Because the wood is green (wet), the walls of the bowl are left thick to allow for warping and shrinkage. As a general rule of thumb, the wall thickness should be 10% of the diameter. So, if you have an 11″ bowl, as shown below, the wall thickness should be approximately 1 1/4″ thick.
Once the bowl has been roughed out I put them in paper grocery bags with wet shavings from the roughing out process. This step slows the drying process and usually prevents splitting and checking. Depending on the thickness, species, and relative humidity, the roughed out bowl could be in the bag for 2 months or 6 months or more.
This roughed out bowl just came out of a paper bag with shavings. It had been in the bag for 3 months. Note how the rim rises at the center and falls at the edges. This shape is the result of the bowl shrinking as it dried in the bag. Also note the round circle in the middle. This is the pith, or center, of the tree. Ideally the pith should be removed from a bowl blank because it is not stable and will usually crack.
Another option for drying green roughed out bowls is a sealer such as Anchorseal. Anchorseal is a wax based sealer that you paint on a green blank after roughing it out. The Anchorseal allows moisture to slowly leave the bowl preventing it from cracking. I have tried using Anchorseal and it has some advantages and disadvantages when compared to the paper bag option. I liked that I could see the bowl and it’s characteristics. I found that it took longer for waxed blanks to dry. It is also kind of messy to apply and if you make a live edge bowl the bark would be covered in wax. I also do a lot of burls that have bark inclusions, holes and crevices and the wax will get into these imperfections affecting the finishing process.
You may be asking yourself, how does he know the bowl is dry? For less than $20 I bought a small digital scale at Walmart. I weigh the bowls periodically until the weight doesn’t change. For waxed bowls this is easy. For the paper bagged bowls, I wait about three months and take them out of the bag. At this point there isn’t much moisture left in the bowl so cracking is minimized. I will then weigh the bowls on a regular basis.
I also bought a used, pinless moisture meter on Craig’s List. After purchasing the meter I found out that this process is more complicated than I thought so I abandoned the use of the meter.
At this point in the process the roughed out bowl is dry and is ready for the final turning. The tenon on the bottom must be trued to round and a flat surface created on the bottom of the bowl so that the 4 jaw chuck can hold the bowl and it will run true on the lathe.
I will be completing the process in the near future. SITE UNDER CONSTRUCTION!!