the southwest U.S., frequently inspire form and design features. These patterns are often geometric in design and thus are easier to recreate than more fluid forms found in nature. Stave constructions are assembled like barrels—cylinders constructed from multiple long, vertically oriented pieces. As a rule, the grain in a ring-constructed turning runs horizontally in the finished piece, while the grain in a stave-constructed turning runs vertically, from top to bottom. Another category of segmented turning called Open Segmented Turning is similar to ring construction but small gaps are left between the segments. Successive rings are offset so the segments interlock with the ring above and below. This type of segmentation seems very delicate and is somewhat transparent but it is generally quite strong. This concept was introduced by Yosh Sugiyama in the early 1980s. A segmented turning can combine ring construction, stave construction, and solid, non-segmented wood as well in a single piece. However, wood expands and contracts in the direction perpendicular to its grain as a function of its moisture content, itself a function of ambient humidity. In this case, during design and assembly, the turner has to be mindful of the impact on long term structural integrity of assembling the constituent pieces into incompatible, non-parallel grain directions. An important variation of the ring construction technique is known as "bowl from a board". Imagine a flat, square board bisected to create two identical rectangles, like two twin beds placed side-by-side to form a king-sized, square bed. Rings are created by cutting concentric semicircles from each of the two boards, one concentric half-ring a mirrored-shape of a half-ring from the other. The semicircles are typically cut with a bandsaw, but a scrollsaw, jigsaw, or coping saw would work. The blade of the saw used to cut the semicircles is set at an angle from the vertical, typically 45-60 degrees, such that when each mirrored pair is glued together to form a complete ring, the rings are shaped like cross sections of a cone. The rings are then stacked to create a cone-shaped blank. An incredible variety of visual effects can be achieved as a function of how the boards are constructed before the concentric rings are cut. Historical impact and modern evolution There are ongoing discussions as to whether turning is a trade, craft, or an art form. Turning in its original form was certainly utilitarian. The surname "Turner" may