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
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
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
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
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.