Electric Longboard

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Long time goal of mine to build as a means of personal transportation
Able to build it using the resources at my first Co-op at Dassault Systèmes
Wanted to experiment with different prototyping methods and gain practical experience
I required myself to use as minimal store bought components as possible
Goal to go at least 30 mph with 20 miles of range

A lot of this project revolved around 3D printing and therefore lots of prototyping, experimenting, tolerencing, and design iterations
Had to design a working drivetrain that would reliable hold a 3000W motor in place and deliver power into the wheels
Needed to learn how to use SolidWorks CAM, G-code, and a CNC machine to produce designs
Worked to create 3 different iterations of design
Created custom wheels with 3D printed nylon cores
- Over-molded a polyurethane rubber tired mirroring injection molding techniques
Completed drive-train by making 3D printed carbon fiber gears to connect a wheel and motor together
- Needed to ensure proper tolerencing on teeth to stop skipping
After assembling components together I was able to get the wheels moving using a power supply

Designed a custom electrical system of this board
- Used an open source BDLC motor controller made for electric longboards
- Created a custom battery bank in a 10s 5p configuration held by 3D printed housings.
- Had to learn enough about electrical systems and diagrams to be comfortable enough about high voltage systems
Had to program the motor controller to have proper gains once the power was connected

Designed a remote control using open source resources
- Built using Arduino Nano's and NRF24L01 over radio frequencies.
- Had to work through a number of bugs in the code
- Needed to read and digest the electrical schematic to recreate it
- Soldered together the final circuit
- In the end got the remote working at a 30 foot range
The last step of this project was creating a housing to protect everything
Decided to take an extra challenge and make it out of carbon fiber
I CNC'd a mold out of foam and set about the many preparation steps necessary such as epoxying the mold.
- First attempt at this was far from perfect and I lost vacuum pressure about half way through the injection
- Second attempt went much smoother and this time used a slightly different process to make it stronger

Even after combining all of the mini projects together there was still a lot of work to integrate the subsystems together
The first successful qualification test was on June 15th, 2018 in a 2 mile loop
Many components went through multiple iterations
- The battery trays alone had to be changed 9 times to ensure a proper tolerance
- The remote was upgraded recently to include a small OLED as a data read out
The electronic have manged to stay together and have put up with the abuse of riding

The biggest trouble so far has been the carbon fiber housing
- Had not proven to be as durable as initially thought but is very aesthetically pleasing
- Does not stand up to the abuse of repeated removal
- Happy that it has worked for 6+ months to begin with

The board is most often used to reduce my 15 minute walk to and from campus
Has remained a continual project that captures my attention
Currently working on constructing a new housing out of aluminum to replace the carbon fiber one
- Will insulate the inside with foam to eliminate electrical hazards

Not only showcased known skills but learned quite a number of new ones in the process
Learned and elevated SolidWorks design skills
- Put to use training learned through the Co-op
- Worked alongside 3D/physical model to plan design in real-time
Learned new skills CAD modeling in SolidWorks CAM and the Surfaces toolbox
- Able to learn CNC and G-code to make parts on my own
Prototyping skills using 3D printing, molding, soldering, electrical engineering, hand and power tools, and compositing among many others

The most relevant skill was the ability to quickly learn and then apply new skills to the task at hand
New requirements constantly adapted and changed as I learned new nuances about this project
Finally, the ability to see a project through completion

STERLING GRAY