Electric Longboard

•Intro

NOTE: THIS BUILD WAS ORIGINALLY STARTED IN LATE 2014 WHEN PART 1 OF THIS TUTORIAL WAS POSTED. I'VE FINALLY FINISHED IT THIS SUMMER -- SKIP TO STEP 6 FOR DECK AND FINAL ASSEMBLY!

This may be the most extensive AND expensive project I've taken on to date. I thought the idea of taking such a comfortable and convenient method of transportation, and making it electric, would be a great service to myself, as well as a fun project. There are quite a few parts of this build that are quite easy, and just a few that are difficult, and require some thinking and problem solving.

Get the Parts

• Trucks: Caliber 50 IIs
• Motor: 63mm Turnigy SK3 Brushless motor
• Wheels: Orangatang Kegels (80mm)
• Bearings: Bones Reds
• Timing Pulleys: SDP-SI 36t & 15t (0.2 in pitch)
• Timing Belt: 0.2 in pitch 65t
• Electronic Speed Controller: 120A 6-10s HV Turnigy Bulletproof ESC
• Batteries: 2 x 5 cell 5000mah Li-Po (Turnigy)
• Receiver and Transmitter: Hobbyking Bargain bin rx/tx system
• BEC: Hobbywing 5a 5v/6v BEC
• Enclosures: Aluminum Extruded enclosures (one for batteries and one for the electronics)
• Longboard Deck: Home made
• Misc: Wire, Bullet Connectors, Heatshrink, Silicone Caulking

Wheel Pulley Setup

In order to transfer energy from the motor to the wheel, we need to attach a pulley (aka gear) to the wheel. I chose XL pitch pitch pulleys, which are very similar to the HTD 5mm pitch pulleys. With a 245kv motor (245 rpm per volt) I wanted a gear ratio of around 0.4. I came up with a 36 tooth pulley for the wheel, and a 15 tooth pulley for the motor.

The next step is to attach the larger pulley to the wheel. The wheel that I chose already had holes around the center, so all I had to do was drill out the holes to accommodate the bolts I used.

I then drilled out the center of the pulley and filed down the trucks accordingly to make room for the pulley.

Then I centered the pulley as best as I could and bolted it on.

Trucks, Motor Bracket

Preparing trucks axle for a custom bracket..

Mounting the bracket..

Wiring

Next was to make a wiring harness to connect the batteries in series and then connect those batteries to the ESC. In addition, wires had to be soldered onto the mains so that I could draw power the operate the BEC (Battery eliminator circuit) which then in turn powers the receiver. This just was a simply harness consisting of bullet connectors for the batteries and an extra connect with the ends bridged to turn everything on and off. This step can be done in multiple ways...

Testing Rig

I wanted to make sure everything worked together so I installed all the components onto a piece of plywood. At this stage I made some adjustments, like configuring the speed controller.

I did not enable braking or soft start (braking was too aggressive and soft start caused jerks even when the throttle was increased steadily)

One thing that I noticed at this point is that if your pulley is not centered on your wheel, it will cause very bad wobbles as the distance will change between the motor and the center of the wheel... I will be working on the pulley to center it better...

[ END OF PART 1 - NOV 2014 ]

The Deck Setup

Once I finally returned to this project, the first order of business was figuring out where everything is going, the arrangement of the components on the deck, and how to mount them. I have decided to make my own deck as it seemed pretty simple and fun to do. What was needed was 3 or 4 quarter sheets of 1/8" plywood, wood glue, some splints, a table saw, jig saw, and clamps. Stain and polyurethane for the finish, and some griptape if you plan on staying on your board!

The process of building the deck involved a lot of wood glue to bind all four sheets of plywood together, ending up with a board that's 1/2" thick. Since I used quarter sheets of plywood, I was limited to a maximum length of 48" for my board. In order to add slight curvature at the ends, I clamped the center of the board to the table, with splints placed under the ends of the wood stack.

To create my shape template, I drew out the outline on a large sheet of paper. You can just draw one side, then fold the paper down the center and trace out the other side, so it's symmetrical. I cut the design out and traced the outline onto the wood. I recommend using a table saw to cut the board along the long sides, to get nice straight cuts, although a jigsaw will work fine. I did use a jigsaw for the curved ends, and the sanded the entire board.

Before applying finish to the wood, I measured and predrilled all of the holes for the trucks and electronics boxes. Countersinking the holes on the top of the board is an excellent idea so that the screws don't stick out of the deck when its all done.

Then, I applied one layer of Early American wood stain, and followed it with two layers of red stain/polyurethane 2-in-1. This gave me the final rich wood color which I liked, so I left it at that. Who knew plywood could look so good?

Putting It All Together

For the batteries and electronics I used some extruded aluminum boxes that I bolted onto the bottom of the board. The electronics box needed to be close to the rear trucks (the motor) so the battery box ended up closer to the front.

First, I mounted the trucks with the drive assembly at the rear. Next was the electronics box, which contains the speed controller, battery elimination circuit, and RC receiver. The box had no flanges, so I needed to drill through it. I just used low profile bolts to not take up a lot of space in the box. A Dremel tool is good for notching out openings for the power wires on the front and back plates.

Finally came the battery box, which had flanges with holes which made mounting pretty easy.

Grip Tape

Grip tape is mostly a safety thing but it can also make your board instantly more stylish. With some careful designing I found a pattern that would hide all of the bolts from the top but still expose nice sections of the plywood. To draw the stencils, I used the paper template I already had from making the deck. Then I cut them out with scissors and traced the shapes onto the grip tape.

Pictures

Since I ended up selling this baby on eBay, we took these "marketing shots" with my sister's camera...

If I were to do it again...

This build took me over 2 years from concept to finished product, and along the way I have learned a few things that would lead me to go about the project a bit differently next time. In fact, I just may build one again!

• Motor: The motor I chose was a bit of an overkill. In fact, the acceleration was scary! I think if you went with a slightly smaller motor you could gain better range and save some money for little to no performance loss. Unless, riding up steep hills is your thing!
• Motor Mount: I have found that with this homebrew method of attachment, is that it is VERY difficult to center the wheel pulley on the wheel. It seemed to ride fine but I wasn't happy with it. There are now multiple machined aluminum options on the market, which are reasonably priced and should assure a perfect fit.
• Speed Controller: There is a new, open-source speed controller designed specifically for e-skateboards on the market, called the VESC. It handles current limits, better performance at lower RPMs (starting from a standstill), and smoother speed ramping. This should solve the jerkiness problems which occur with hobby-grade speed controllers, such as the one I used.

Thank you for reading this post and I hope it helps in your future projects!