My vessels are created using a technique called Open Segmented Construction. This involves cutting each individual piece of wood or segment and gluing them together to form geometric patterns when they are turned. A small gap is left between each segment that becomes an intergal part of the pattern.
I start by preparing a plan. On each of my designs I need a cutting list as shown on the right. This is a profile of the finished work with calculated dimensions for the segments. To make the calculations I developed several specialized formulas. Using these I can plug parameters into a handheld computer and get cutting dimensions.
When I work with more complex designs I will also use special graph paper to lay out the pattern as shown on the left. I color code for each type of wood so I know the correct sequence when gluing the segments.
Next I choose the wood I am going to use. In this example I have selected holly and purpleheart. Locating new and replacement stock is a large part of my work. About a third of my stock is domestic hardwoods with the remainder coming from South America and Africa. I typically maintain a pallette of 35 - 40 hardwoods from which to choose.
The table saw is used to cut the boards into stock used for segmenting. This stock is cut a little thicker than the thickness of a segment. The original design determines this thickness.
The medium sized bowl I am building requires 328 inches of stock (about 27 feet). Of that about 71 inches will be turned into sawdust when cutting out the segments. Of the remaining 257 inches, 94% will be removed during turning; leaving just 16 inches of stock in the finished bowl. And thats if I don't make any mistakes!
All stock is dimentioned to the correct thickness in a sanding machine. The allowable tolerance in thickness is held to .005 inches and the stock must be absolutely flat and parallel. The stock is then sanded to a smooth finish (150 grit) to provide the best gluing surface possible.
Based on the design, the segments are cut on a special table saw I developed for just this purpose. I use a micrometer to insure the width of the segments does not vary by more than .003 inches (slightly less than the thickness of a sheet of paper).
Here I have cut the all of the segments for one row on the bowl.
This is where I glue the segments to form the bowl blank. The wood structure in the foreground is a jig to position each segment as the glue dries. On the far side of the lathe headstock is an index wheel used to set the radial position of each segment as it is glued.
The bowl is assembled in rows with the lowest row first. As each row is finished, the positioning jig is moved out slightly, the segments for the next row are cut and then glued. This process is continued until the bowl blank is complete.
Here is the bowl after turning and finishing. It is 4½ inches in diameter and 2¼ inches high. It contains 711 segments and took about 4 days to complete.
The complexity of this turning is midrange of all of my work. Some can get very complex and require up to 2 months to complete. Currently, on average, I produce about 2 turnings a month.
I have written a book, Segmented Woodturning, in which I have described in detail how to make these vessels. Using the procedures in the book a person with minimal woodturning skills will be able to construct a simple open segmented vessel. The book cost $14.95 plus shipping and is available from me or the publisher, Schiffer Publishing Ltd. Their website is listed in the links section.