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Electric Longboard
May 2016
This is the project that inspired me to become a mechanical engineer. I designed and built an electric longboard for my high school engineering class final project.
I designed and fabricated the deck and motor mount from stock materials, learned the basics of drivetrains and gear ratios, and was exposed to circuitry and soldering.
This project had so many setbacks, but it was super rewarding because I learned a lot and I got a fun toy that can go up to 21mph.
CNC Milled Motor Mount
CNC Milled Motor Mount
Original design
Original design
Cleaned up with an angle grinder
Cleaned up with an angle grinder
Our engineering lab had a Hass CNC mill and I was able to get this motor mount machined out of aluminum. This was one of the first parts I had ever designed, so it had some major flaws:
It was too thick where the motor attaches and the motor shaft was not long enough to reach through. I had to remove material with an angle grinder.
The open hook attachment design would come loose from vibration. I was able to drill two holes through the top surface and synch down a thin strip of metal with two bolts; this locked the motor mount onto the hanger.
I learned what tolerances and fits were the hard way when the mount would not fit onto the hanger initially; it took a lot of filing to make it fit.
This part was designed so poorly, but I love it because I learned so many important lessons at once.
Deck Fabrication
Deck Fabrication
I glued three sheets of 1/4" birch plywood together and cut out the deck profile on a band saw. I drilled out the mounting holes, applied a waterproof sealant, and stuck on the grip tape.
Electrical
Electrical
My first time soldering. I had to attach compatible connecters to all the electrical components.
My first time soldering. I had to attach compatible connecters to all the electrical components.
Drivetrain
Drivetrain
40T gear and a 16T pinion for a 2:5 gear ratio.
40T gear and a 16T pinion for a 2:5 gear ratio.
V2 - 2020 Update
V2 - 2020 Update
I have been working on designing a new board from the ground up and applying the skills I gained while working towards my ME degree. My goal is to design a 2 wheeled direct drive system. The motors will directly attach to the rear wheels for a 1:1 ratio. Direct drive has the same benefits as a hub motor but provides better cooling.
Due to the pandemic, I no longer have access to my university's machine shop, so I have been using my 3D printer to prototype in the meantime.
Motor Mount
Motor Mount
3D printed using PETG.
3D printed using PETG.
Direct Drive
Direct Drive
Custom hanger for direct drive system.
Custom hanger for direct drive system.
Failure Analysis
Failure Analysis
The printed hanger held up fine going straight but failed after a hard turn.
The printed hanger held up fine going straight but failed after a hard turn.
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