Introduction

In this post, we detail the build process for the SkateMetric Patriot, the most powerful, affordable, and hassle-free DIY mountainboard out there (see our video overview). This guide may serve as a precise blueprint, or merely as inspiration for a design of your own, so don’t be afraid to substitute parts. If you decide to venture off the beaten path, however, be prepared to find creative solutions when parts inevitably don’t fit together quite as planned, and make sure you have the tools listed below.

WARNING: This device is NOT a toy. Well, it is, but it’s an EXTREMELY DANGEROUS toy. Always ride conservatively and make sure you have adequate safety gear. At the very least, buy a certified full-face helmet.

Required Skills

None! If you have two hands and the coordination to operate a drill and a soldering iron, you’re good to go (and if soldering sounds intimidating, don’t worry.. anyone can do it).

Required Tools

Build Components

Major

* Two of the four FLIPSKY motors used in our original builds have begun to fail prematurely. We’ll be switching to these Turnigy SK8 motors, although we haven’t yet tested them.

Minor

Assembly

[Optional] Paint/Grip the Deck

The deck’s stock lion graphic is rather unsightly, so builders may consider covering it with paint or grip tape. It’s easiest to perform this step first, but removing the waterproof box to paint/grip the deck later is relatively easy, so careful planning isn’t required.

Mounting the Trucks

Each truck mounts to the deck with a riser wedge and four bolts (two short, two long), and four nuts. For some reason, the DIYEboard drivetrain kit comes with four riser wedges, but only two are needed (one per truck), and they’re all roughly the same. Below are pictures of the completed truck assemblies for reference. The short bolts are used on the tail-facing ends of the trucks, and the long bolts are used on the center-facing ends.

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To begin, grab a truck, any of the four riser pads, four bolts (two short, two long), four nuts, a screw gun, and a wrench. Start by partially threading the four bolts into the deck such that each one protrudes roughly 5mm from the bottom (or enough to mount the riser wedge, but not enough to mount the truck). Insert the riser wedge over the protruding bolts. Next, continue threading any two diagonally opposing bolts until they both protrude roughly 5mm from the top of the riser wedge. Place the truck over the protruding bolts.

NOTE: The truck may not fit properly over the bolts. If this occurs, back one or both bolts out and re-thread them at different angles.

Once you’ve managed to mount the truck, finish threading the two diagonally opposing bolts, and with the wrench, secure the assembly down using two nuts. Repeat for the remaining two bolts, then repeat for the second truck.

Installing the Motor Pulleys

The proper method for securing the motor pulleys to the motors is via a key and set screws. Unfortunately, while the Flipsky motors used in this build do come with keyways bored into their shafts, they do not include corresponding keys. This leaves you, the builder, with a few options: you can…

a) search the internet for the correctly sized key, which will make the installation process trivially easy (if you can find it)

b) use a dremel tool or sandpaper to fashion your own out of whatever small metal parts you have on hand, or

c) simply secure the pulleys with a strong adhesive such as Loctite red (this is a fairly common practice among DIYers and is incredibly easy).

We chose a combination of options b and c, but have found Loctite red is perfectly sufficient alone. Be warned, however, that once the Loctite dries the pulleys will essentially be permanently fixed, so take care to get the belt alignment correct (this shouldn’t be challenging and there’s a decent acceptable error margin).

Mounting the Motors

Each motor fastens to its mounting arm via four hex screws. Position each motor with the wires facing up (towards the sky) and secure the motor using any of the four screws in the linked kit (we used the longest screws). Be sure to apply a small amount of Loctite to each screw before inserting. Don’t tighten yet–the motor should be allowed to slide along the tracks.

Note: As a bonus, builders may consider inserting small washers between the screw heads and the motor mounts to prevent wear along the mounting tracks.

Preparing and Mounting the Enclosure

Drill two holes (roughly 15mm in diameter) in the back corners of the waterproof box. These are used to route the phase wires, as shown in the picture below.





Next, position the box on top of the deck. Try to center it as best you can, then drill two holes through both the bottom of the box and the deck. Position the holes as shown below to avoid damage as the deck flexes.





Run two bolts through the holes and add nuts on the underside to secure the enclosure (don’t forget to add Loctite). To prevent water/dirt ingress, we recommend applying hot glue or silicone grease around the bolt heads.

Soldering the Electronics

This is not a soldering tutorial (there are plenty on YouTube already; check one out if you’ve never used a soldering iron before). However, to sum the soldering process up in a few sentences, you simply press your soldering iron against the two conductors (e.g. wires, plugs, and other metal stuffs) you wish to connect and hold it until both are sufficiently hot. You then push your solder onto the surfaces near the iron. Upon contact, the solder should melt and run along the joint. Once the joint is nicely covered, remove the iron and the solder will dry in seconds. It’s that easy. And if you’re worried you’ll do a bad job, our soldering joints are some of the ugliest out there, and we’ve yet to experience a single failure, so don’t stress.

Phase Wires

The phase wires are the six wires that connect the ESC to the motors (three per motor). Connecting the phase wires to the motors requires both extending the stock wires exiting the ESC and terminating the extensions with bullet connectors (the little plugs that connect to the motors).

First, measure the distance from your enclosure to the motors and cut the six wire segments needed to bridge this gap. Strip the insulating sleeves off the ends of the wires, leaving about 8mm of exposed wire on each end. Locate the six female bullet connectors you’ll need (they should come with your motors) and solder one to each extender. Search for a YouTube tutorial on soldering bullets if confused. Next, solder the other end of each extender to a phase wire on the ESC (you’ll probably want to strip the ESC phase wires to expose more metal).

ESC Battery Connectors

For the ESC and batteries, it’s best to use the 5.5mm bullet connectors linked above. We use bullet connectors, because they allow the batteries be configured in series with minimal hassle (if you don’t understand the difference between series and parallel configurations, hit up Google). For the batteries, use female connectors for the positive (red) terminals and male connectors for the negative (black) terminals. For the ESC, use a male connector for the positive terminal and a female connector for the negative terminal.

Connecting the Phase Wires

With everything soldered, you can now connect the motors to the ESC. Each motor is connected via three phase wires and a Hall sensor cable, and the four cables will be bundled within the linked braided sleeve. Before connecting anything, cut enough sleeve to span the distance between the motors and the enclosure, and slide it over the four motor cables. Use hot glue to secure the enclosure end of the sleeve to the waterproof box. Repeat for the other motor. You can now connect the motors to the ESC (the bullet connectors may be connected in any arrangement you like).

[Optional] Anti-spark Switch

The diagram below illustrates the anti-spark switch (the component within the dotted box) and its proper integration within the electrical system. As you can see, building one requires only two pairs of 5.5mm bullet connectors, some wire, and a resistor. The path through the resistor can be built using narrow wire (little current will be able to flow this way), but the main path must be constructed from heavy duty 12 or 14 AWG wire to avoid overheating. The resistor in the diagram is actually built by combining four 1k ohm resistors in parallel. Once you’ve built the switch, connect the plugs in the order specified by the diagram to avoid sparks while starting up your patriot board.

Programming the VESC

If you’ve never programmed a VESC before, check out this video tutorial from FLIPSKY. Here are the important current settings to dial in for each ESC:

Maximum motor current: 100A*

100A* Maximum reverse motor current: -75A

-75A Abs maximum current: 400A

400A Maximum battery current: 100A

100A Maximum regen battery current: -15A

* We ran into problems with magnetic saturation somewhere beyond this point with the FLIPSKY motors, although you may be able to go higher.



In addition to applying the current settings given above, we’d also recommend navigating to the app settings and lowering the throttle ramp-up time from the default value of 0.3 seconds to 0.1 seconds.

Charging the Batteries

You can charge the batteries individually using a 6S balancing charger like this. For bonus points, however, you may also consider building a very simple adapter for a standard three-stage charger like this, which will allow you to charge both batteries at once (be sure to balance them from time to time though, or you could start a fire). Creating a converter is as easy as soldering two bullet connectors to a coax charging port, like this.

Simple adapter in a plastic case

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