Turning a segmented bowlThis article by Pekka Svinhufvud
First I draw the shape with intended wall thickness, 5 or 6 mm. Then ring diameters are drawn with some margin for roundness and position errors. The segments lengths are calculated from the drawing.
Segment lengths (outside edge) are calculated:
segment length = outer diameter * 3.14 / number of segments.
This bowl has 12 segments /ring so segment length for 200 mm diameter will be:
200 * 3.14 / 12 = 53.6 mm
Ripping the material comes first. Boards must be of equal width and thickness. I use my bandsaw, but a table saw can also be used. I thickness the boards with a simple homemade thickness sander. I cut the segments with my homemade miter saw, but a table saw can also be used.
Then the bowl is sanded with several grits and finished with several applications of Danish Oil.
After the oil is dry (next morning) the bowl is buffed with paper towel while the lathe is running.
Lastly the bowl is cut from the face plate with a parting tool, then the bottom is finished.
This is only a short description of segmented turning, there are excellent books and videos and if you are interested search the Web for "Segmented Woodturning".
Pekka's tilting router lift
Brian Kerr's router lathe
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