Michel Richards suggests using a jig to calculate the length of segments for a segmented bowl.
For an open segment bowls, Michel Richards’ jig may require some minor adjustments, but, that would depend on your personal adjustment for desired gap. Typical for open segments, you might choose to use 66 – 70% of the length of a closed segment.
This article describes the use of the jib for a closed bowl. Michel’s original suggestion is found on the video at https://www.youtube.com/watch?v=CYeZm5ELH0.
For an N segment Bowl (N being the number of segments intended):
- Create a drawing with a wedge that would be a 360/ N degree center angle (ex: 360/12 = 30° for a 12 segment layer). Each line of the V would be 180/N (ex: 180/12 = 15°) off a vertical line.
- If you make a 12-segment wedge, 12 wedges together would create a closed 12-sided polygon.
- For any given layer, figure out what radius the bowl should be at that layer.
- Look up the center line of the V (or up his side measuring strips of the jig), to a bit more than the radius wanted for the bowl at that layer.
- Position your slider at that radius above the wedge vertex.
- Measure across horizontally from line to line of the V.
- You now know the correct larger edge of the segment trapezoid you need to cut for that layer.
