Motor, assembled from kit #11

Difficulty level: 1 (the simplest, no special tools required)

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pdficon_smallKit contents: Kit #11, Kit #12

If you want to purchase one of these simple inexpensive kits, click here.

If you want to understand how they work, click here.

Read all instructions carefully and check the Safety Rules before you start!


  1. Glue together two 2×2 rotor pieces as shown*. Pay attention to their alignment.


  2. Insert the motor shaft through the holes and center it.

    Rotor with shaft

  3. Add plastic sleeves (washers) to both ends of the shaft. They fit tightly and require some effort. You may put the sleeve on the table and push the shaft in with the negative end of the battery. Leave a small gap so the sleeves are slightly above the surface of the knobs.
    Left sleeveRight sleeve

    If you notice burrs on the plastic sleeves remove them with a sharp knife.

    BurrBurr removed

  4. Glue magnets to the rotor with the letter ‘S’ facing outside. If you want to try 2 magnets first, glue them to the opposite sides.

    Magnets on rotor

  5. If you want your rotor look better you may cut out the white glossy round labels that are provided and paste them to the magnets. It is recommended to use regular white glue or a glue stick on the labels for better results. This step is optional and may be done after you finish your motor.

    Magnets with labels

  6. Assemble rotor on the base plate. Try to spin it by hand. If it does not spin freely you might need to squeeze blue bricks slightly together to push plastic shaft sleeves in. There should be a tiny gap between sleeves and inner sides of the bricks with holes.

    Rotor on base plate

  7. If you purchased the kit #12 with ready to use electromagnet, skip steps 7 – 10. Otherwise slide the 1×2 brick with two holes on the electromagnet core to the mark as shown.

    Electromagnet core

    If the brick is loose you may use super glue to prevent it from sliding while making the electromagnet.

    The position of the brick is important. It defines the length of the electromagnet. If it is too long it will not fit; if it is short the motor will be less powerful or will not work at all. Mark on the core should be OK but you may find more precise position by checking it on the board as shown below. Smaller gap makes faster and more powerful motor.

    Spin the rotor and make sure that none of the magnets hits the electromagnet!

    Check electromagnet position

  8. Measure at least 5” (13 cm) of the wire and fold it.

    Leave open end at least 5" (13 cm) long

  9. Tape the folded end and wind all the wire in one rotational direction (either clockwise or counterclockwise) moving back and forth along the core. All spool wire should be used.

    First wraps

  10. When there is about 5” (13 cm) of wire left, secure it with a cable tie.

    Assembled electromagnet

  11. Remove the insulation from the wire tips with fine sandpaper (included) or a sharp knife.

    Remove insulation from wire tips

  12. Assemble electromagnet on the base plate.

    Electromagnet on base plate

  13. Attach the battery holder to the base plate.

    Battery holder on base plate

  14. Insert the battery and briefly connect electromagnet wires to the battery. If nothing happens switch the wires. With the correct connection electromagnet repels the permanent magnets and the rotor stops in the position shown.

    Electromagnet test

  15. After you found the correct connection trim red (positive) wire from the battery holder and corresponding electromagnet wire. Remove the insulation from the wire tips and twist them together. You may tack this connection under the battery holder.

    Connect positive (red) wire

  16. Fasten the reed switch to 1×2 brick with side holes using cable ties. Trim them with scissors.
    Attaching reed switch - step1Attaching reed switch - step2Attaching reed switch - step3
  17. Assemble the reed switch on the base plate. Trim the wires as necessary and remove at least 1” (2.5 cm) of insulation.

    Reed switch on base plate

  18. Wind bare wire ends tightly around the reed switch contacts.

    Connect wires to reed switch

  19. If the head of the electromagnet is lower than the rotor axle you may add small 1×1 brick as shown to have a better alignment. It also provides additional support for the electromagnet.You may tape the electromagnet wire that is connected to the reed switch to the side of the rotor stand (clear tape is shown).

    Taped wire and supported electromagnet

Spin the rotor by hand. Make sure it does not hit the electromagnet, reed switch or wires. You should hear the click every time the magnet passes the reed switch.

Your motor is ready! If it does not start on its own you may need to give it a slight push. Generally if your battery is fresh it should start rotating without the push if you find the correct position of the electromagnet and the magnets on the rotor sides are centered.

You may glue bricks together and to the plate if you do not plan to disassemble it.

Visit our site at for principles of this motor operation, troubleshooting, speed measurement, and other related questions.

Enjoy your motor! We hope you had fun building it.

* Colors of the parts may vary.

This is not a Lego® product even if it contains Lego® bricks and plates. All warranties provided by Simple Motors.

LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize or endorse this product or these assembly instructions.

1 Comment

  1. You may need to give it a tiny push if it does not start on its own. If you find the correct position of the electromagnet and the magnets on the rotor sides are centered, it should start revolving without the push if your battery is new. Thank yo so much!

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