This article does not explain the layout and geometry of segmented bowls, about which there are other articles and books. Instead, it explains a method for making segmented bowls with nonlinear, ornamental inlays. The methods explained here may be neither original nor the best; however, I enjoyed figuring them out myself and offer them to you for use and/or improvement. If you are one of those persons who just can't wait to crank a piece of wood into a lathe and start turning, this technique may not be for you because most of the work is in the preparation of bowl inlays and segments.
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Segmented bowls are typically made up of rings of glued-up wedges, as illustrated in the picture to the right. Makers of more ornate bowls vary the wood and patterns of the wedges to create non-curved designs in the side of the bowl. Many of these ornate designs would remind you of Navaho art patterns. My interest in segmented bowls came as a result of the love of turning and the desire to do something useful with wood scraps. Since many of these scraps are small, I more often turn out smaller, 8-sided bowls whose wedges are cut at an angle of 22.5 degrees. Angle accuracy is important so I cut templates using an Incra Miter Gauge and use these templates to set saw and sander angles. |
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| Not wishing to spend inordinate amounts of time hand-cutting and fitting inlays into wedges, I devised a router table/shaper jig that allows you to safely rout/shape small pieces with a high degree of accuracy and repeatability. This jig, shown to the right, accepts 1/4 in. thick template inserts that ride against a top-bearing 1/2 inch router bit. The purpose of the jig is to(very) firmly hold small work pieces of various sizes on top of the template. Each design requires a male and female template, which is made by drawing your design on a piece of paper, attaching the paper to a piece of wood (that fits perfectly into the jig's template cut-out) using, say, 3M Super 77 spray adhesive and then cutting out the curve with a jigsaw or coping saw. If necessary, trim up the templates so they have perfect male/female matching curves. |  |
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The trick to inlaying (elongated) wedges to create two identical halves, glue them together and put the 22.5 degree bevel on each side. It is important that all pieces be uniform in length and square lest things get out of kilter on the glue-up. Using the jig and a router table or shaper, cut 16 (for an 8-sided bowl ring) identical pieces consisting of half a wedge segment piece and half of an inlay. Glue the two together and put into a vise or clamp to get them to seamlessly mate. When mated, the inlay piece (which is darker in the illustration to the right) will have excess that must be trimmed off before the two halves of the wedge-to-be can be joined. |
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Once the male/female pieces are (tightly) joined, it will probably be necessary to clean up the face of each wedge half before joining to the other half. I prefer to use a disc sander to do this but you must take care to keep the face your sanding parallel with other face if things are to fit together later on. I've gotten to the point where I can freehand the sanding but clamping a scrap perpendicular to the disc to use as a guide is a good idea when starting out. It is also important that the table be square with the sanding disc. Sanding can also be done by hand using sandpaper on a flat surface such as a sheet of glass or saw table top. |
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| Once the 16 halves are joined into 8 wedges-to-be and glued up, it is necessary to bevel each side to the required angle (e.g., 22.5 degrees for 8 sides). I've found the safest and easiest way to do this is with either a cutoff sled or a sliding saw/shaper jig, such as the Delta model shown in the picture to the right. Note that the right-most hold-down has been moved off of the wedge piece for illustrative purposes. It is important that the small piece be fimly held parallel to the saw blade. The left hold-down is used to secure a miniature sled that rides on the jig. As previously stated, I use a template cut with an accurate (Incra) miter gauge to set the blade tilt to the proper angle. |  |
| When all eight elongated wedges have been beveled, I glue them up two at a time by hand. What seems easiest is to vigorously rub glue into the two bevel faces so there's little or no excess that will squeeze out and then press the two together by hand and hold tight for several seconds. Having no excess glue in the joint gives you a quick set. Be sure to glue them up so the inlay runs the same way in all pieces. More than once I've stupidly mismatched the patterns by not paying attention during this step in the process. |  |
| Glue up the wedges into two bowl halves and don't go any further until you first sand the faces of each half flat. Regardless of the precision of your bevels, you probably won't get a perfect without this step. Then glue the two halves together in the same manner as described above. I used to use band clamps to hold the two halves together but careful fitment and glue application (rub it in with little or no excess) makes this unnecessary. Once the glue is dry, the piece can be put into the lathe chuck. |  |
| The next step is to chuck up the piece and clean up one end to accept a sacrificial bottom piece that becomes both the bottom insert and the piece that holds the bowl in the chuck for final turning. Make sure the insert doesn't fit either too loose or so tight as to not seat well once glue is applied. When dry, the piece can be turned around and put in the chuck the other way for turning, sanding, burnishing and finishing. This is the fun part. Enjoy!! |  |
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