Three-wheel Electric Longboard

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Introduction: Three-wheel Electric Longboard

About: After a degree in micro-engineering in Switzerland, I moved to Russia to discover new landscapes

After riding my electric bike for a whole summer I had to remove the battery for the winter. Moreover the controller died when I was NOT riding (I have my theory why) so I had a battery and a motor unused at home. I then decided to make another electric vehicle.

In Moscow it is important to have something light that can be taken in the metro and carried in the stairs (there is a looot of stairs in Moscow). This vehicle had to be a skateboard or a scooter. So I made an hybrid: half skateboard and half scooter.

Despite appearances there is a lot of novelties on this machine:

  • Three wheels
  • Foot speed control
  • Foot rear brake
  • Foot strap
  • Free wheel mechanism

Step 1: Tools and Material

Except for the laser cutter and the 3d printed, it is mainly tools that can be found in anyone's garage. Thank you fablab77 for the facilities!

Tools

  • Laser cutter
  • 3d printer
  • Jig saw
  • Drill

Material

  • Plywood 15mm (1000 x 200 mm)
  • Skate truck with wheels (65 mm)
  • Scooter wheel (175 mm)
  • Screw M8 x 100 (rear axle)
  • BLDC Motor 325Kv 1800W

Step 2: Shape the Board

My first reaction was to open my CAD software and start modeling the board with everything beautifully integrated. Quickly I realized that I do not know which dimentions to enter and I even do not know if the principle would work. Would it be stable? Would it turn with only one truck? The answer was to close the computer, think a little bit and make a prototype as fast as possible.

Some considerations about longboards

  • The shorter the board, the shorter the turning radius
  • The truck angle changes the turning radius
  • Having one truck has several effects
    • It doubles the turning radius
    • It is easier to incline the board (even with harder bushing) and also easier to flip the board.
    • The pivot point is moved to the rear which increases stability: When turning, the board comes back under the rider's center of mass.

Conclusion

  • I chose a board length of around one meter to be comfortable on it but still have reaction in turns.
  • I increased the truck angle (+15 deg) to compensate the fact that I have only one truck and so the turning radius is divided by two.
  • I added the front strap to be able to lift the board with the foot.
  • I added reinforcement in V shape under the board to add rigidity in torsion.
  • The board has a narrow rear to avoid flipping it.

Step 3: Make the Board

Take your plywood, draw the shape you want and cut is with the jig saw.

I mounted the truck on a raiser pad angled at 15 degrees.

Then I mounted the rear wheel with two small playwood plates.

Finally I added the V reinforcement to increase torsion rigidity.

Now you need to test the board so go for a ride.

Step 4: Mount the Motor

If the board works well, we will now electrify it.

I 3D print an adapter to mount the freehub sprocket on the wheel. I also (laser) cut an adapter for the sprocket to the belt.

The pulley on the wheel has 75 teeth and the motor pulley has 15 teeth so the reduction factor is 5.

Step 5: Add the Electronics

Now we can add the VESC controller, the button and the battery.

The controller is set in order to increase the torque slowly when the button is pushed. The explanations are clear on the VESC site to know how to program the controller. There are two pins where you can have an analog input and in the software there is the option to increase slowly the current (torque) instead of doing the backflip when you touche the button.

I placed the button on the front of the board just after the strap. Just test and see how your foot is positioned when you ride.

Now the controller is really smooth but I will increase the reactivity for the next ride.

Good ride! stay safe!

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    4 Comments

    0
    Honus
    Honus

    1 year ago

    Love it! That belt drive to freewheel sprocket adapter is brilliant.

    0
    AdrienR
    AdrienR

    Reply 12 months ago

    Thank you!

    0
    RyanMake
    RyanMake

    1 year ago

    Two Questions.
    1. What material is the adapter because that it a great idea that I would like to use sometime and I am wondering if you went with a harder material to handle the strain.
    2. What sort of laser cutter did you use to cut a 15mm board so cleanly?

    Also what is your theory about why your ESC died?

    0
    AdrienR
    AdrienR

    Reply 12 months ago

    1. It is made of PLA then I glued the cog on it. The outside pulley is made of acrylic I think (plexiglas maybe).
    2. The board itself was cut with a jigsaw. The laser cutter was used only for the battery box and the pulley.