Converting a Robotic Motor For Lego Blocks

The Internet has brought a lot of advantage to life, not the least of which is access to really cheap electronic parts. [KarelK166] was buying cheap geared motors for projects, but they didn’t easily work with Lego blocks. He found an easy way to adapt them and–lucky for us–decided to share.

The process is pretty simple. The gearbox has two screws and an elastic band holding it together. Once the gears are exposed, you can drill a hole in two of them with a 4.8mm drill bit. This might take a little practice since the gear needs to hold still, but you also don’t want to crush the plastic teeth. You also need to enlarge a hole in the casing, but that’s easier to clamp down in a vise.

Once the holes are in place, you can put a Lego axle in there and reassemble the gearbox. Attaching a Lego plate with epoxy is the last step. We would have been tempted to use a larger plate and build an H-bridge and maybe a sensor for an encoder right on the plate.

This might be just the ticket for those pair of self-lacing shoes you want to make. If just drilling some holes in an off-the-shelf motor isn’t enough of a hack for you, you can always build your own motor.

7 thoughts on “Converting a Robotic Motor For Lego Blocks

  1. i adapted a 5g servo to lego sacrificing only 3 lego parts. i dremeled off the mounting tabs flush to the servo casing. then i cut the peg end off an axel-peg adapter just by rolling a razor blade around the base of the ridge on the peg side. the peg was sanded flush to the ridge. i superglued it to a clipped servo horn and drilled out the center to accept a screw to make an axel-servo adapter. i put it in a lego motor to sand the horn round. i then built a jig out of lego using an x brick to accept the adapter, which was screwed down to the servo for a tight fit. i built the jig so that i could position the servo between a pair of 2×3 plates. then it was just a matter of filling the gap with hot glue and a razor blade to remove the excess. ended up with a servo brick that was about 2 bricks and a plate high. the servo overhung it a bit but it worked out quite well.

    in the future i think i will just 3d print an adapter. though any mod using parts on hand is a good idea. other side of it is modern lego motors arent that expensive. this at least gives you some more options.

  2. I just took a lego motor cable (RCX era people) cut it in half and now I had two cables I could use to control a 9v lego DC motor with a SN754410 and an AVR on a breadboard. I was going to do a PCB that had it all so I could do mindstorms with just AVRs + AVR.io and C but that got shelved fast.

  3. My Boys are Lego Fanatics. They have gotten more legos them most 100 kids put together.
    Or maybe I could say 6 – 8 large bins. They are planing it will take them all summer to sort it out the way they want it.
    I had tried to help them out a long time ago.
    And They told me if its not legs throw it out.
    So I had to give up.
    Me My self I think its a great idea.

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