Build your own drone
This versatile drone can be used for racing, acrobatics or aerial photography. It’s a great way to learn about the hobby.
Years ago, if you wanted a quadcopter you had to build it. Now there are several companies producing affordable, easy-to-fly multirotors that fly straight out of the box. But that doesn’t mean the days of DIY drones are over. In fact, there has never been a better time to build your own. Drone components have become cheaper and more modular, and the software that controls them is more stable and easier to use than ever before. Even if your ultimate intention is to fly a Parrot ANAFI or a DJI Phantom 4 Pro, there is a lot to be gained from building your own quadcopter first. You’ll end up with a much better understanding of how the different flight systems work together and you’ll have an aircraft that is much more versatile. That gives you a chance to experiment and find out whether you really want a glasssmooth aerial photography platform, or a high-performance racing quad. And a home-built drone is much easier to repair yourself, if you have some crashes along the way.
The steps here will guide you through the process of building a miniquad. This uses the popular ZMR250 frame. All the other components are available from hobbyking.com/au and similar sites. It will take about ten hours to assemble if you’ve never built one before. At the end of it you’ll have a quadcopter that can take HD aerial video, fly at 25kph and stay in the air for over ten minutes on a single battery.
01
MOUNT THE MOTORS We’re using Emax 1806 brushless motors. These come in clockwise and anticlockwise flavours, but this only affects the direction of the thread for the ‘prop nut’ that secures the propellor to the top. The actual motors can spin in either direction, but using the opposite thread on the prop nut means that the torque from the motor serves to tighten the nuts in flight. You can just use clockwise threads on all four motors if you like, but make sure you use nyloc nuts instead of the supplied prop nuts, otherwise your propellers will quickly work themselves loose. Mount each motor in the centre of the X-slots, using a dab of Loctite on each screw. Trim and strip the wires so they reach about a third of the way along the frame arm and ‘tin’ the ends with solder.
02
SOLDER THE ESCS
You need one electronic speed controller (ESC) for each motor. These take the low-power control input from the flight controller board and turn this into a high-power output that drives the motor. A quad of this size needs ESCs rated for at least 10 amps, so we have opted for 12A Afro ESCs, which come with the latest SimonK firmware. ESCs come with bullet connectors on the output leads. You can solder corresponding bullet connectors onto your motor leads, but you’ll end up with wires that are much too long for a miniquad like this. The neatest solution is to cut the heat-shrink plastic off the ESC, desolder the three motor leads entirely and solder the wires from the motor directly onto the circuit board. Commercial circuit boards use high-temperature solder, which can be tricky to melt using a hobby soldering iron. Melting some extra solder onto the pads helps because the two solder types form an alloy that is easier to melt.
03
POWER DISTRIBUTION SYSTEM
The bottom plate of the frame will carry the power from the battery to each of the four arms. Because the motors draw significant current, you’ll need fairly heavy gauge wire. Use 14AWG (American wire gauge) for the battery connector and 18AWG for the ESC connectors. That’s about 1.6 and 1mm diameter respectively.
All the arms share a common positive and negative connection to the battery, so the simplest way to connect this is to use two small strips of brass or copper mounted in the middle of the frame, with positive on one side and negative on the other. Cut two 15cm lengths of 14AWG wire and solder one to each plate, so that they run to the back of the quad. Solder a male XT60 connector onto these two wires. This will be your battery connector. Now solder four 18AWG wires to each plate, long enough to reach each arm of the quad. You can either solder these to the power leads coming from the ESCs, or desolder the supplied leads and solder yours directly to the circuit board as before. The clearance between the bottom and middle plates of the frame is very small, so make sure your cables cross each other as little as possible. It’s a good idea to connect a spare pair of wires to the plus and minus plates, with a connector on the other end, just in case you want to power any other components directly from the main battery in the future.
04
SECURE THE ARMS Make sure all the exposed electrical connections are insulated with heat-shrink tubing or electrical tape. This is especially important with a carbon fibre frame, since carbon fibre conducts electricity. Feed four 10mm M3 bolts for each of the arms through from the bottom of the frame and add the mid plate. Make sure the power wires are routed properly with none pinched between the arms and the frame, or crossing the bolt holes. Secure the arms with M3 nyloc nuts. The threewire ribbon cables from the ESCs should run over the top of the mid plate. Feed eight 16mm M3 bolts through the remaining holes in the bottom and mid plates. Screw the tubular aluminium standoffs onto these bolts. Don’t overtighten the ends, to avoid bending the plates together.
05
THE FLIGHT CONTROLLER
We chose to use the Naze32 flight controller as it was cheap, easy to fly and simple to configure. If your flight controller didn’t come with headers pre-soldered, your first job is to solder these pins to the connection pads. It’s a good idea to plug some connectors to the other end to hold them in place while you do this, since the heat from the soldering iron can soften the plastic that keeps the pins aligned. You can mount the flight controller on the frame using nylon standoffs or just use a self-adhesive foam pad. A triangle on our Naze32 indicated which way was ‘forward’, but it was actually more convenient to mount the board with this facing right. This made it easier to access the microUSB port for configuring the board later.
06
THE RADIO RECEIVER
The radio receiver needs 5V and ground to power it, so we can take this from one of the ESCs. Carefully prise the red and brown wires out of the connector and use heat-shrink tubing or a two-pin Dupont connector to insulate them from each other. We have chosen the FrSky V8FR-II radio receiver, which has eight channels. The top row is for ‘signal’, and the ground and 5V connections are all common again, so you can just plug the power wires from the ESC into any channel. The signal wires run from each channel on the receiver to the block of 2x5 pins on the Naze32. Fix the receiver to the frame with a blob of hot glue.
07
CONNECT THE ESCS
Each of the ESC ribbon cables has an orange wire for ‘signal’, red for +5V and brown for ground. Plug them into the block of 3x6 pins on the Naze32 with the signal wire on the innermost pin. Motor 1 is back left, 2 is front right, 3 is back left and 4 is front left. The pins for motor 1 are marked on the Naze32 with a dot. The flight controller can handle up to six motors, but we only have four, so two outputs will be unused. The ground and 5V connectors are all common, which means you actually only need to connect these wires from one of the ESCs, which comes in handy for the next step.
08
CAMERA AND BATTERY
Use the rubber damping washers to fix the camera plate to the top plate of the frame. These can come loose in a hard crash, so it’s a good idea to also use wire or string through the centre as a backup. Now you can bolt the top plate to the aluminium standoffs, using M3 bolts. The Mobius ActionCam and 2200mAh 3S LiPo battery are secured to their plates with Velcro straps.
09
CONFIGURE CLEANFLIGHT
To configure the Naze32, you’ll need Cleanflight - Configurator from www.google.com/chrome/webstore. On the Welcome tab is a link to install the CP210x driver that allows your Mac or PC to talk to the Naze32. Now click the Firmware Flasher tab and select the most recent Naze32 firmware from the drop-down list. Click Load Firmware [Online]. Now connect your Mac or PC to the Naze32 with a micro-USB cable and click Flash Firmware. Once the board has been updated, the software will connect. There are lots of settings you can play with, but the most important is on the Modes tab. Under Angle, click Add Range and drag the sliders until the yellow bar covers the entire range. This ensures your quad always flies in self-levelling mode, which is the easiest for beginners.
10
CHECK THE MOTORS
Gently test the throttle to check the motors spin the right way. Motors 1 and 4 should spin clockwise, 2 and 3 need to spin anticlockwise. If any are wrong, all you need to do is unsolder and swap any two of the black wires from the ESC to the motor to reverse its direction. If you mounted the flight controller facing right, make sure you set the Board Alignment Yaw adjustment to 90º, otherwise the Naze32 will try to fly your quad sideways. Now you can fit the propellers and take it for a test flight!