Krazy Kan: a Classic Rollback Toy





Introduction: Krazy Kan: a Classic Rollback Toy

About: Dad. Science and engineering teacher.

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

Key Materials:
Rubber band
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)

Non-essential items:
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!

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    17 Discussions

    Woo! I never even knew how that thing worked, and now I know, plus I can make a really big one myself. I am totally make one.

    Hi, this is absolutely a fantastic toy! The only thing I am concerned about is the safety! I do apologize if I missed something along the way but the pencil to a certain age child would be considered a choking hazard right? You think if the wood end cap and the pencils were glued over that would eliminate possibility of them pulling it apart and chewing on it? Just some thoughtful ideas, REALLY LOVE this idea though :) .

    i had to do this for a school science project. I really wish i'de seen this instructable.

    I am voting for this roll-away and come back toy. I also entered a rubber band powered roll away, but this looks cool.

    1 reply

    Thanks Bruce. I admire the elegance and efficiency of your designs. They are really great for making with kids. I will be making some of your Altoid Cars. My kids will love them!

    . That's great. . I've seen the plastic lid used for an end cap. Probably not as good as a stiff piece of wood, but you'll probably have it handy and you don't have to worry about cutting it to the right size.

    1 reply

    Yes, the project would be easier (especially for kids) to construct if the plastic cap was used. I'll try it with a smaller diameter can and/or try to reinforce a plastic cap in some way without using all the power tools. Thanks for the suggestion.

    Thank you. I'll enter it in the rubber band contest. Thanks for the suggestion.