Designing a Basic Segmented Bowl Using Your Computer

This article was reprinted with the permission of Kevin Neelley. For more information about him and this technique you can visit his website.

This article is similar to my "Designing a Basic Segmented Bowl" article except that this one uses my Table Saw Miter Angles program. This alternate method of bowl design uses no math and very little sketching and drawing. The computer performs all the calculations necessary to turn a bowl sketch into segmented rings. This article is intended for the beginning segmented bowl maker. I have made one design sheet to help the beginner through the design phase. The steps below will show you how to design a 12-sided segmented bowl that has 9 layers of segments.

The picture to the right is the bowl that is designed in this article. After you're done reading this, you can read more about how to make this bowl. You can also see the plans for a frame-miter table saw sled that makes perfect ring segments.

If you make a similar bowl and follow these steps, your bowl will turn out fine. Don't worry about the details of segmented bowl construction. Instead, spend your time thinking of an original design that you like. I'm sure that experienced segmented bowl turners don't make bowls using all the steps on this webpage. I don't make segmented bowls this way either, but I think it's a good learning approach. Experience will tell you how to modify the steps. Until you are experienced, you shouldn't modify the steps until you understand how the changes will affect the segmented bowl construction.

Click on the images to enlarge them.

Figure 1

This blank design sheet is used for drawing the outline of your bowl. This sheet is big enough to design a bowl 12" diameter by 12 ring levels tall. Each row, 1 through 12, corresponds with a ring level of your bowl design. The grids on the sheet are intended to be 1" wide by 3/4" tall to make it easy to measure bowl ring dimensions directly from the sheet. But, I found that every printer seems to print the grids at different sizes. So, I suggest printing out one sheet then using a photocopy machine to enlarge the sheet to full 1" grid width.

Design Step #1

Draw the right-hand half outline of the new bowl on the sheet. This is the first step in the design process. If you want to see what the whole outline looks like, hold the left side of the sheet against a mirror so you can see the reflection of the sheet. The entire outline can then be viewed. This design has 9 rings. The bottom ring will be a solid disk. The other 8 rings will be segmented. I have decided to make the top, middle, and bottom rings from purpleheart and the rest of the rings from maple. The bowl will be made from 3/4" thick kiln-dried lumber, purchased from a local lumberyard.

Design Step #2

Draw the inner surface outline of the new bowl on the sheet using 1/2" wall thickness. The 1/2" wall thickness does not mean I'm going to turn the bowl to 1/2" thickness. The 1/2" is just a reasonably safe design thickness. You can turn your bowl thinner. On the other hand, if you don't make your segmented rings very accurately and they end up egg-shaped or the wrong diameter, then 1/2" might not be big enough. We'll take our chances on this one because I'm using a really accurate mitering sled.

Design Step #3

I have drawn the inner and outer ring radius lines for each ring on the sheet. The Table Saw Miter Angles program uses the inner and outer ring diameters and the number of segments per ring.

Design Step #4

On the sheet, measure and record all the inner and outer ring diameter dimensions for use with the Table Saw Miter Angles program.

Fill in the "Project Setup and Design" box of the Table Saw Miter Angles program for each segmented ring and print the sheet. The sheet will have all the calculated dimensions necessary for cutting the Ring #2 segments.

Design Step #5 - Ring #3

Do the same thing as you did with Ring #2.

Design Step #5 - Ring #4

Do the same thing as you did for the previous rings.

Design Step #5 - Ring #5

Do the same thing as you did for the previous rings.

Design Step #5 - Ring #6

Do the same thing as you did for the previous rings.

Design Step #5 - Ring #7

Do the same thing as you did for the previous rings.

Design Step #5 - Ring #8

Do the same thing as you did for the previous rings.

Design Step #5 - Ring #9

Do the same thing as you did for the previous rings.

Now, all dimensions necessary to cut the segments for all the rings for this bowl have been calculated. I'll use these dimensions to cut boards to length and width, and then cut segments from the boards. It looks like I need about 40" of 1"x6" kiln dried maple and about 14" of 1"x4" purpleheart to make this bowl.