1. Segmented Woodturning Symposium October, 2018 James Rodgers
Open Segment Woodturning An overview of techniques Part One - PReparing
Segmented Woodturning Symposium
October, 2018
James Rodgers

2. Open Segment is “GAPS” Pieces are not assembled in a “ring”
Can be very small to very large
Using small colored pieces creates complex designs

3. The Basic Reference
Published on 2002

4. Dennis Keeling book Published in 2012
Focus on open segment construction
Contains basic information on the SegEasy plate use

5. My Book Published 2016 for SWT symposium Covers Basics
Open Segment construction
Seg Easy
Dizzy bowls
Segment pens
Feature ring designs

6. Basic terms
Segment Width
Segment Edge Length
Segment/Board thickness

7. Basic terms
Segment total angle
Actual cut angle

8. Simple math
Segment edge length = Circumference ÷ # segments

9. Segment included angle
Simple math
Segment included angle = 360 degrees (circle) ÷ # segments
Segment cut angle is ½ of above
Segment included angle

10. Math example
Ring diameter is 10 inches
We desire 12 segments / ring

11. Math example Ring diameter is 10 inches We desire 12 segments / ring
Diameter 10 x (π) = inches Circumference

12. Math example Ring diameter is 10 inches We desire 12 segments / ring
Diameter 10 x (π) = inches Circumference
Segment edge length ÷ 12 = 2.6 inches

13. Math example Ring diameter is 10 inches We desire 12 segments / ring
Diameter 10 x (π) = inches Circumference
Segment edge length ÷ 12 = 2.6 inches
Segment included angle is 360° ÷ 12 segments = 30°

14. Math example Ring diameter is 10 inches We desire 12 segments / ring
Diameter 10 x (π) = inches Circumference
Segment edge length ÷ 12 = 2.6 inches
Segment included angle is 360° ÷ 12 segments = 30°
Segment cut angle is 30° ÷ 2 = 15°

15. We need a Shape!

16. We need a drawing!

17. Add ring thicknesses
Ring (stock) thickness

18. Calculate segment width
OR-IR = Segment Width
Outside Radius
Inside Radius

19. Now we have all the dimentions
Segment Width
Segment Edge Length
Segment/Board thickness
Segment cut angle

20. Ring segment construction
Segment edge length
Ø = 10 inches
12 segments
Cut angle = 15º
Segment edge = 2.6”
Cut angle

21. Open segment construction
Segment edge length
Ø = 10 inches
12 segments
30% gap
Included angle
30º - 9º = 21.º
(30% of 30º = 9º)
Cut angle
21º ÷ 2 = 10.5º
Segment edge
2.6” x 70% = 1.8”
Cut angle

22. Indexing options – home made

23. Alisam Engineering indexing
Includes magnetic locking arm
90, 120, 144 index
2.5º, 3º, & 4º
All spindle sizes
$89.99
Alisam.com

24. Version for small lathes also
Jet mini version
$54.99
20 & 72 holes

25. Iron Fire version Includes wheel and pin only 14, 36, 48, 60 holes
$24.99 all spindle sizes
Ironfirellc.com

26. Indexing diagrams From Bill Smith’s Book 12 – 144 divisions
Positioning jig drawings
On line at:

27. Smith basic jig For on-lathe use only Easy to build
Requires no special accessory
Details in Smith’s book

28. Driskell Design For off-lathe construction
Requires custom threaded fitting
Uses gravity to help
Projects need to be re-aligned after on lathe work
Much faster

29. SegEasy plate 18 & 24 segment versions Fixed 4º spacing
All segments at once
Required precise thicknesses
Lloyd Johnson modification for alignment
dealers

30. Designing the vessel
First create a shape

31. Determine project parameters
Project/stock size
Number of segments

32. Determine project parameters
Spacing between segments
Design choices

33. Create a cut list

34. JLR custom calculator

35. For open segment work I added “radius”

36. Rip stock to width

37. Number all strips

38. Make an “adjustable” cutting sled

39. Each angle requires a separate stop

40. Always use a hold down

41. Purchase and adjustable sled

42. Cut segments

43. Every segments must be sanded

44. Project components ready