Segmented Bowl

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Blog entry by Cousinwill posted 09-17-2010 02:59 AM 13426 reads 3 times favorited 6 comments Add to Favorites Watch

Here are the steps I use to make segmented bowls. The first step show a piece of purpleheart 28” long

Next I adjust the table on my Shopsmith to 22.5 degrees.

This picture shows the purpleheart board cut with the 22.5 degree angle on the edge. This step is very important. If this angle is off everything else after this step will be affected.

Next I cut the 28” board into 8 3” sections

Here I am gluing the pieces

I use a piece of a rubber intertube wrapped tightly around the bowl to hold the pieces together while the glue dries.

Now I cut a piece of wood for the bottom and glue it on.

After the bottom is on, I locate the center of the bottom so I can glue on a piece of scrap wood attached to a faceplate. I insert a piece of newspaper between the scrap and the bowl. This will make removing the scrap piece easier later on.

Now the bowl is attached to the lathe and it’s time to turn.

I have finished the turning and sanded the bowl to 220 grit

The finished project. I applied 8 coats of Tung Oil finish. I leave the faceplate attached to the bottom of the bowl until I finish applying the finish.

-- William from the oldest town in Texas

6 comments so far

View Richard Alexander's profile

Richard Alexander

79 posts in 3561 days

#1 posted 09-17-2010 04:41 AM

What a unique project. Thanks for posting. I’d like to move beyond pens and this looks like it would be fun to do. How did you originally come up with the lengths and angles? (it’s been a few years since I learned that in math class) I might try a smaller version.


-- Richard- Tulsa, Oklahoma

View Cousinwill's profile


131 posts in 3371 days

#2 posted 09-17-2010 05:33 AM

Richard, I will more than likely confuse myself and you if I try to explain this in words. Here is the math I use: each piece of wood has two sides, and there are 8 pieces used to make the bowl. 8×2=16. A circle is 360 degrees so 360 divided by 16= 22.5 . A 12 piece bowl would have an angle of 15 degrees. 12×2= 24 360 divided by 24=15 Hopefully this makes some sense. The lengths are easier. Just decide how tall you want the bowl to be. No big math formula involved. Making bowls are a lot of fun BUT it can be habit forming…......................................

-- William from the oldest town in Texas

View Darell's profile


436 posts in 4075 days

#3 posted 09-17-2010 05:37 PM

Thanks for posting this. I even understand the math which is weird considering I’m terrible at math. One question though, does the math change when figuring out how to turn a bowl like your maple and mahogany segmented bowl or is it still just figuring the total number of pieces you want to include? I’m curious because I like that bowl with the thin strip of contrasting wood. Looks like something I might want to attempt. I really like the way you make these bowls. There’s much less waste than when turning a bowl from a blank. This process works for me since most of the wood I have laying around would have to be laminted into blanks and your way of doing this makes more sense from a waste standpoint.

-- Darell, Norman, Ok.

View BigTiny's profile


1676 posts in 3369 days

#4 posted 09-17-2010 06:19 PM

I believe the math remains the same, you just cut half the pieces in one wood and the rest in ther other. If you want to include narrow dividers, they can be cut straight and just reduce the length of the other pieces by the width of the divider. Example: if your plan calls for 12 sides in two woods and each piece is supposed to be 3 inches long at the outside edge, to add a 1/8 divider between each piece, you’d cut 6 pieces of each wood with the 15 degree cut on each end, but reduce the length to 2 7/8.

Clear? I hope so…

-- The nicer the nice, the higher the price!

View Cousinwill's profile


131 posts in 3371 days

#5 posted 09-17-2010 08:31 PM

Big Tiny is right the angles do not change. The thin strips of contrasting wood had flat sides. By adding the strips you increase the diameter of the bowl. If you don’t want the bowl any larger then cut the main pieces not as wide.
The angle is the most important step in the entire process. If your angle is off slightly you will have a gaps between the pieces. I have found this to be a nightmare to fix. What I started doing was buying pine, which is cheap, running it through the table saw with the angle set. I then clamp then together as I would any other bowl. I check for gaps and make the necessary adjustments on the table saw before I cut any of my good wood.
Darell you are right in this method reduces the amount of waste.

-- William from the oldest town in Texas

View Darell's profile


436 posts in 4075 days

#6 posted 09-17-2010 10:53 PM

That’s what I thought although I hadn’t yet thought it through enough to realize that the thin strips could be flat on both sides. Makes sense. I like the idea of using pine first to make sure the saw settings are right. Could be done with scrap plywood too I think. Thanks guys. Just the kiind of information sharing this site is noted for.

-- Darell, Norman, Ok.

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