Design Process

I started with a set of criteria that I knew I wanted for the board (left). Using these criteria, I researched and developed my own solutions to accommodate each requirement (right). In addition to my criteria, natural requirements arose (bottom left).

After I had the circuit drawn, I pulled out my computer and drew up scale diagrams of the board for sizing and visualization of the board. Shown above is the 2nd rev of circuit diagrams with the same schematic as shown in the Post-It above. Because it is hard to find switches that operate at the high amperages that I am working with, I will be using what are known as loop keys, which are basically two wire plugs turned into a circuit closing device. The scale diagrams are seen at the top of this page next to "purpose" and "goal." Below is a comparison of required actions without a complex circuit versus with this circuit.

CAD

After I had determined what parts to get, I started working on a CAD of the Longboard to help design and visualize what the final product will look like. I started by removing the front hanger from my longboard and taking precise measurements of specific points to create a 3D model of the part. I did this for the three main parts that make up double king-pin trucks, as well as the major parts that make up a skateboard, like the deck and wheels. From there, I designed a mounting mechanism for the motors, then discovered the motors will not fit under my board with enough clearance of the ground. I switched their orientation and designed a three-plate mounting system for the two motors to keep them at the desired distance for the timing belts and pulley's. Based on existing pulley CAD's I designed custom pulley's that can be machined on a CNC mill. To attach my wheels to the driven pulley, I plan to create holes in the wheels with a CNC mill to line up with my custom pulley. Renders of my progress are shown at the top of this page.

Next Steps

The next steps are as follows:

Review motor and ESC power ratings

purchase motors and ESC's

Test and prototype motor mount design

Purchase wires and (XT90) connectors

Solder according to schematic

Design and build/3D print housing for batteries and ESC's

Test using old RC radio system

Purchase or design handheld remote

Design mounts for powerful headlights, side reflectors, and brake/taillights

Getting it Moving

I was excited to get the board moving, so I threw together all the components I bought, which included plenty of soldering, and some filing to get the mounts (which weren't designed for these trucks) to fit on my dual kingpin Gullwing Sidewinder II trucks. These trucks are fantastic trucks that are stable at higher speeds around 25 mph, yet still allow plenty of carving, which is absolutely necessary when riding around a college campus. I clamped down on the trucks with the set screws on the motors mounts, and realized that there wasn't enough room on my 9" sidewinders to fit both motors. I tried it out with one motor attached and realized that the whole system couldn't even push me. Something was wrong, but I didn't know what.

I ordered the 10" sidewinders, which are the same dual kingpin design, just wider. I immediately used a file to create flat notches for the monstrous set screws that hold the motor mounts to the trucks, then attached both motors. There is not enough room under my board for the motors to fit toward the center of the board, so I mounted them facing the back of the board, as you can see in the image above.

The way that the bolt pattern worked on the motor mounts didn't allow for me to use the drop through in the deck. I used top mount to get things moving.

Instead of using all four batteries, I decided when the components all arrived to just go with the simpler route, and use only 2 batteries in parallel. This was effectively a 6s system, running at 22.2V nominal with 10,000 mAh (and way too many amps available)

I didn't have a proper enclosure for the batteries and electrical components, so I used an old cardboard iPad box, which was the perfect size. I used bungee cords to hold it to my board. Everything, including the batteries, was mounted toward the rear of the board. This made the center of balance quite uneven.

I used my mac running VESC tool on windows via bootcamp to reprogram the VESC. Since the speed controllers shipped with 12s as the default expected voltage, the board thought it should be in low voltage cutoff mode, which provided barely any power at all. I changed the setting to 22.2V nominal, or 6s, and the board finally started, and it packed quite a punch too. My friends who tried it were knocked off their feet. Literally. The punch was a little too powerful, so I adjusted the remote/response curve settings. This made throttle control much smoother without sacrificing the power that the board could deliver.

After working up my confidence, I probably got to about 15 mph. There really was no way for me to tell at that time, and I didn't need to know. I just knew that the board was fast enough for me to get around campus, though I was testing in the parking lot of the elementary school in my neighborhood.

The pulleys I designed fit perfectly in the Kegel wheel cores (as I had intened). The holes were a little tight for the screws, but I was still able to thread them through and clamp down on the other into the molded plastic of the Kegel wheels (I basically used oversized bolts to thread into the plastic holes). After many miles of quick accelerations, deceleration, and even some off-roading, these pulleys are still working perfectly. The only downside is that the abs teeth seem to be slowly wearing out due to friction with the belt. This is negligible to me (again, still waiting for any signs of failure to show up), especially since the cost of material for both of these pulleys was about $2 total. I already had the steel bolts from the original kit designed to work with the ABEC core's. I would 3D print pulleys like these for future use, given they are a quick, cheap solution that works really well.

Motors

I have no pictures of this upgrade, but it was more of a fix to a problem that shouldn't have existed. Essentially, the outer motor magnet housing/assembly started coming loose from the axle it was attached to... the main shaft of the motor. I drilled and tapped holes into the sides of the motor and through the shaft so that I should physically connect the shaft to the outer motor assembly with a bolt instead of relying on two small set screws tightened onto the shaft.

Motor Mounts

The motor mounts have come loose a number of times due to different reasons. After using copious amounts of red loctite and even some epoxy, I don't think the motor mounts will come loose any time soon.

Drop Through

When I re-adjusted the motor mounts, I made sure to give myself room to adjust the motor angles a little lower. This allowed me to position the motors at the perfect height to mount my trucks to the deck in the true drop-thru style it was intended to be. This gave me a board with the lowest possible profile. It is even lower to the ground (more stable) than the famous Boosted boards.

Next Steps and Why I Haven't taken them yet

Next steps for this board include the following:

• shave down the width of the battery enclosure to be able to print in one piece

• design better mounting system for enclosures using bolts

• design work on rear enclosure to allow for better clearance around motor wires

• incorporate taillights and headlights (already designed)

• incorporate telemetry package (have components)

• order bigger wheels (85mm caguama)

• add nighttime reflectors

Why have I not done any of this? Well, I decided that I wanted to build an entirely new board. One that was going to be built better in every way that the original board wasn't. After this new board is built to satisfaction, I will go back and upgrade the old one to use around campus, and when I need a lighter 'safe bet' board. Turns out my old board is also just much more fun to ride. It's more carvey, as the other one was built more for speed than carving.