Jim Helle


PRO Member
I recently bought 3D Design and Woodturner Pro. I designed a 12 segment bowl of open segments. When I designed it it says my angles should be 8 degrees instead of 10. Any thoughts as to why. I'm afraid the rings won't be right when I cut them.

Lloyd Johnson

Staff member
Hi Jim,

Fortunately, you can ALWAYS rely on the calculations presented by Woodturner PRO as they are always correct (12 years of history has made me extremely confident of this). Here's an example:

Let's say that you have a ring with 8 closed segments. The cutting angle would be calculated at 22.5 degrees. Now if you were to change it to an open segment row with eight segments and an open segment gap that equalled 50% of one segment, you would now have the equivalent of 16 closed segments, but every other one would be a gap. So even though the number of segments stays at 8, the angle to cut them is now 11.25 degrees instead of 22.5. As you change the size of the gap, the cutting angle will continuously change.

If you are using one of the SegEasy plates, everything becomes simple as both the 18-segment and 24-segment plates have gaps that are four degrees. In practice, what this means is that the cutting angle for the 18-segment plate will ALWAYS be 8 degrees and the cutting angle for the 24-segment plate will ALWAYS be 5.5 degrees. If you are using these plates and look closely at them, you'll find that this is engraved into each plate.

I have recently modified the software in Build 3.1.009 that changes the gap from being specified in percentage to specifying it in degrees with a default of four degrees so if you are using either of the plates, you don't have to do anything but specify the number of segments you want per row. As long as the box is checked at the start of the field where you specify the degrees, the cutting angle will always calculate 8 or 5.5 degrees. If you uncheck that box, you can now specify whatever you want as a gap so you are now in a complete manual mode.

I have a new tutorial that will be coming out soon that shows how to make a table saw sled that has two settings - 8 degrees and 5.5 degrees and it lets you cut multiple segments at a time using a home made flip stop. I hope to get this done in the next couple weeks as I will be gone over the holidays. Since I work fulltime, though, my time is limited.

Anyway, I hope that helps, but please let me know if you have additional questions.