Summary

This device can help you make equilateral triangular legs for the Division C Tower Event in the Science Olympiad. This helps people who don't want to sand the legs manually using sandpaper but don't have an electric sander. You can make all the legs very consistent, don't need to worry about sanding off too much using the sander.

This design is inspired by YouTube Balsa Engineering https://www.youtube.com/watch?v=MTHygxUS3YU You should go check out that YouTube video if you don't know why do we need to make triangular legs.

Materials and Tools

3/16" square balsa wood stripes

R4-2RS Bearing 1/4" * 5/8" * 9/32"

SC-7 Tungsten Carbide Grinding Bit 3/4" Diameter (Length will be shorter than the one shown in the picture, I can't find the exact same one)

Power Drill

Printing

Stretch the “Feeder.stl” in Z direction only to the maximum print volume of your printer

Layer Height: 0.2mm

Supports: None

Infill: Cubic 20%

Filament Material: PLA+

Assembly 

1. Insert the bearing to the side with a smaller hole
2. Insert the grinding bit through the other side with a larger hole, pass through the bearing, and attach it to the power drill.

Usage

1. Wear proper protection, safety goggles, mask, and gloves
2. Attach the wood stripes to the wider side of the feeder
3. Push the feeder through the sander, the rotation direction of the sander should be opposite to the direction feeding in, as shown in the picture, so the feeder will not fly out the sander too fast
4. Do this again using another feeder slot, so both sides of the stripe will be sanded to 60 degrees
5. Finished and start building your tower, good luck in the Science Olympiad