Picture of Octagonal Bowl (Box Joints)
Box joints are traditionally used to join two pieces of wood at a right angle, with the tabs sanded flush with the surface of each board.  Using extended length box joints on an octagonal bowl, with its 45 degree angles, creates an interesting effect on both the inside and outside of the bowl.

This instructable shows how to design, cut out, and assemble the pieces used to make such an octagonal bowl.

I made this at TechShop www.techshop.ws
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Step 1: Materials and Equipment

Vector drawing software (I used CorelDRAW)
Laser cutter (my TechShop has a Trotec Speedy 300)
150 grit sandpaper
5 minute epoxy
Clear polyurethane
2-1/2" x 15" poplar (1/4" thick)
5" x 5" poplar (1/4" thick)

This instructable assumes some basic familiarity with CorelDRAW and a laser cutter.  If you don't have access to a laser cutter, you can still cut out the box using other tools such as a scroll saw or coping saw.

Step 2: Start Designing the Box Joint

Picture of Start Designing the Box Joint
2b SixVertical.png
Each finger of the box joint will be 0.2" tall, so start by drawing a 0.2" long vertical line.  Create five copies of the line with a vertical gap of 0.2" (either drawn manually or with the step and repeat function).

Make sure that you set the line width to hairline so that the laser cutter knows that you want to cut these lines and not just engrave them.

Step 3: Complete the First Box Joint

Picture of Complete the First Box Joint
3b OneJoint.png
Now draw a 0.75" long horizontal line starting from the bottom of the top-most vertical line.  This establishes the length of the finger joint.  Using the same technique as the vertical lines, create 9 copies of the horizontal line spaced vertically 0.2" apart.  Then close the open ends of the box joints with 0.2" tall vertical lines.  This completes the first box joint.
Hi. Nice, detailed instructable. You might try using superglue (CA glue) instead of epoxy to hold your bowl together. See my Instructable for Stacked Laser Cut Bowls at http://www.instructables.com/id/Stacked-Laser-Cut-Bowls/. I wick ultra thin superglue between the joints and it holds the bowls together quite well.
I know these a "Finger Joints" since many techniques could be used to make a "box". They are a variation of a Dove Tailed joint.

I like this application, but I wonder how fine you could make your fingers? A laser cutter ought to make fine fingers much more easily than cutting by hand.
WhiteTech2 years ago
I love Tux the penguin on the front!
Awesome! I love the penguin and I love the design of the box!