Introduction: Krazy Kan: a Classic Rollback Toy
You may recall your father or grandfather making this toy for you. Science classes often use it as a discussion springboard for an inquiry into how such a "mystery" can works like here in NY state and this document from the Resource Area for Teachers (RAFT).
Step 1: Gather Materials
Nails, rod or pencil
1/4" plywood for can end cap
Drill with a bit larger than 1/8th inch diameter (hard to stuff rubber band through 1/8"hole)
Hammer (just in case)
Hot glue gun (decided not to glue on the end cap to make it easier to inspect the can "guts" and be able to easily modify as necessary)
Dental floss/Wire (potential weight securing materials - not used)
Step 2: Make Endcap
1. Trace out can end on piece of 1/4 inch plywood.
2. Saw out wooden endcap with a bandsaw or jigsaw.
3. Sand to fit.
Step 3: Drill Holes
1. Drill two holes in metal end of can about 2-3" apart.
2. Mark hole location on wood with pen through holes in can.
3. Drill holes in wood.
Step 4: Thread Bands
1. Thread bands through holes.
2. Attach weight to the center of low tensioned band.
3. Use nails to secure bands.
- I recommend a hole larger than the 1/8" holes in the photos. It was hard to thread the rubber bands.
Step 5: Test
Adjust the rubber band tension and the weight position as necessary to ensure can rolls back properly.
- Some designs use only one one rubber band through the center of the can (along the rotational axis).
Step 6: Secure Weight
1. Connect weight securely to rubber band knot
2. Add tape
Step 7: Replace Nails With Pencils
-Replace nails with something more kid-friendly, like colored pencils.
1. Mark notch locations.
2. Cut notches.
Step 8: Remove Label and Decorate
Remove label and decorate!