So here is a former project that has seen better days. My electric longboard was a project generated out of need. In Florida, there are two seasons: summer and slightly less intense summer. Living off-campus left you with few options to get to class: riding the notoriously unpleasant public transportation or battle the elements and get to class on foot/bike/unicycle etc… After doing much research and snagging what I thought was a killer deal of a road bike on craigslist, I gave the latter option a try. Without fail, every single time I took it to class, I was dripping with sweat. Let’s just say that it wasn’t a pleasant experience. Then I saw a trend of commercial electric longboards, the most notorious was branded “Boosted board”. The $1000+ price tag was definitely a bit of sticker shock as the first thing that came to mind was “that will cut into my beer budget!” Thus began my build adventure because I thought I could do it for a fraction of the price.
I was able to use some common of-the-shelf components and the longboard in my closet to build effectively the same thing with some improvements. My “masterpiece” piggybacked on the bottom of my longboard and was protected from the elements by a dollar store Tupperware. While it did the job it was brought into this world to accomplish, it was never something I was proud to show off.
The system architecture was as followed: The brains of the system was supplied by an Arduino nano that received it’s commands via a serial communication from a HC-06 Bluetooth module. The brawn was supplied by a Turnigy Aerodrive SK3 280KV brushless motor and a 100AMP ESC (electronic speed controller). Everything was fueled by a pair of 3 cell LiPo batteries. The electronics were rather straightforward as it was essentially the same as an RC airplane, the interesting and head scratching part revolved around trying to translate the power from the motor to the wheels. This was accomplished buy taking an 1/8″ bar of aluminum as a motor mount and TIG welding it to the “pot metal” that is pretending to be aluminum of the longboard axle (lots of oxidation).
After drilling and countersinking some holes for the motor mount, I was able to flush mount the motor on an axis that was now parallel to the axle of the rear wheels. Even though the motor I purchased had plenty of torque, it wasn’t enough to move a “very lanky” student like myself even on a mostly flat Florida campus, therefore I multiplied the torque using a gear reduction. I purchased a 14 tooth small sprocket for the motor and then 3D printed a larger 40 tooth sprocket that would slide into the spokes on the wheel. The final connection between the two pulleys was accomplished by a neoprene drive belt, this had the advantage of providing a bit of give and absorbed a lot of small bumps and jerks that a chain drive wouldn’t which provided for a smoother ride.
