Part 2: Construction

Now that you’ve read through all the theory, you should have a broader understanding of the ins and outs of a quadcopter. As always, getting your hands dirty is the best way to learn!

The Build

3D Printing

There are a two main 3D printed parts for the drone: the motor mount, and the base. You will need to print out four motor mounts and two bases. The recommended infill is 20% using a hexagon or grid pattern.

Drilling The Holes In Arms

Grab the four arms and match one arm to each slot in the base. Use masking tape and a pen to number each arm and slot, so you can match them later, once you drill the holes. Use a scribe or fine tip marker to make a mark for where you need to drill.

Now, it’s time to drill the holes. I recommend using a drill press, but a hand drill can also work fine. If you are using carbon fibre, make sure you have a vacuum to suck the carbon (you don’t want conductive carbon inside your drill).

Glue Mounts

Once the motor mounts have been printed it’s time to glue it together with the legs and arms. To allow the glue to stick properly, roughen up the sides of the arms and legs with 80 to 120 grit sandpaper.

Next, mix both parts of the five-minute araldite epoxy. Use about a 20-cent-piece worth of hardener and resin for each section. Make sure to mix it well in order for the glue to set properly. Apply it inside the mount and around the tubes, and secure the tubes to the 3D printed motor mount. Make sure the holes are facing the right way.

The glue should be able to hold it in place within five minutes. It will be completely set in 24 hours.

Attach Arms To Base Plates

Use the M3 x 25 screws, washers and nuts to secure the arms to the two base halves, then secure the nut with threadlocker (also known as thread-locking fluid).

If you haven’t used threadlocker before, apply a small amount to an area of the screw thread where the bolt will be making contact. Threadlocker isn't essential, but it's a prudent measure. Your drone creates a lot of vibrations, and it will help to avoid things rattling themselves apart!

Attaching Propeller Mount To Motors

Some motors do not come with the propeller mount installed. Place the mount on top of the motor and use the M2.5 screws to screw it down. Make sure you apply a small drop of threadlocker to the screws. Do not apply too much as it could leak into the bearings of the motor.

Soldering Bullets To Wires

Luckily the motors come pre-soldered with male bullets, so we only have to solder the female bullets.

In preparation, strip 5mm off each of the silicon wire pieces and cut 12 pieces of 3cm-lengths of 6.5mm heat shrink.

Tin the wire and then solder the bullet to the wire. Soldering bullets can be tricky so may require a bit of practice to get right. The best way I found to solder bullets is to use helping hands and a temperature of around 380°C for your soldering iron. After you tin your wire, place it inside the back of the bullet, then feed your solder through the bullets with a hole on the side. Place the soldering iron tip at the back and heat up the tinned wire. Then start feeding the solder, you want the solder to completely fill the space. Once its filled, remove the solder and soldering iron. This should give you a strong connection between the wire and bullet.

Once the bullet has cooled down, cover the bullet with a piece of heat shrink. Make sure you leave 1mm overhang at the front of the bullet so you can make a flush seal when you heat the shrink.

Solder Wire To ESC

Strip 5mm off the other side of the silicon cable, tin the cable and then tin the unsoldered pads of the ESC. Solder the silicon wire to the pad.

Screw Motor To Motor Mounts

Line up the holes of the motor to the motor mount, then use the M3 x 10 socket head screws to mount the motor in place. Again, make sure to use a small amount of threadlocker to prevent the screws from loosening.

Power Distribution Board (PDB)

Screw in the brass standoffs into the four holes in the centre. Then screw the PDB into place with the left over standoffs.

ESC

Place the ESC into the provided plastic case and cable tie the ESC to the arm.

Connect the bullets of the motor and ESC together. Usually motors will not have colour-coded leads, but fortunately these motor leads are colour-coded. Make sure the middle cable is plugged into the middle cable of the ESC. Otherwise, if it is spinning in the wrong direction, switch around the left and right cables. Use the DIYODE logo as a reference for the front of the plane, as per the following wiring diagram.

Do not cable tie down the cables until the spin direction of each motor is confirmed (we’ll go through this later).

Solder the positive and negative power leads of the ESC to the ESC pads on the PDB.

Power Module

It’s time to install the power module. The power module is used to power the flight board as well as to provide current and voltage data, so we can monitor it on our ground station.

First cut the female XT-60 connector and strip 5mm off the positive and negative ends. Then use VHB double-sided tape to secure the power module to the body. Next, solder the power cables to the raw battery inputs of the PDB.

GPS Mast and GPS

Using the half-pan head screws, attach the GPS mast to the base. We use a GPS mast to reduce the interference produced by the spinning motors that the compass (which is built into the GPS) may be susceptible to.

Attach the GPS to the top of the mast using VHB or the provided double-sided foam tape. Make sure the arrow on the GPS is pointing towards the front of the quadcopter.

Cable tie the GPS cable to the mast to keep things neat.

Receiver And Telemetry

Since the Pixracer accepts SBUS, we will be using the SBUS mode on the FrSky X4R receiver. The X4R uses port 1 for the SBUS protocol, therefore use the servo lead to 5-pin JST-GH connector to connect port 1 to the RC port of the Pixracer.

Use VHB to secure the receiver underneath the body of the quadcopter and feed the cable towards the centre.

For the telemetry module, cable tie it to the bottom left-hand arm (which supports motor 2), and run the cable towards the centre.

Flightboard

Using the nylon M3 x 6mm screws, attach the flight controller to the brass standoffs. Some flight boards require vibration isolation, but the Pixracer is fine to hard-mount onto the body.

Safety Switch And Buzzer

Fit the safety switch cable through the hole first, and push to secure. Use some VHB to secure the buzzer inside the two body halves. Run the cable towards the centre.

Wiring

Plug in the GPS, power module, receiver, telemetry module, safety switch and buzzer cables to the flight board using the wiring diagram here. The ports are also labelled on the flight board.

Battery Strap

Feed the LiPo battery strap through the two large slots in the body.

ESC Allocation

Yay. we are almost done!

Check the spinning direction of each motor and plug it into the right port. To do this I recommend using a servo tester. They are cheap and make it extremely easy to check the direction of the motors, without having to install firmware onto the flight board, or use the configuration software to spin the motors. Alternatively, go with the DIY method and make your own servo tester with an Arduino.

Depending on your servo tester, you may need to power it with 5V. After plugging the LiPo battery into the power module, you should hear sounds from the flight board and ESCs. Wait for the sounds to stop (it should take about five seconds), and following the diagram below, plug Motor 1 into an output on the servo tester. Turn the knob slowly and observe the direction of spin. If your motor is not spinning, some ESCs require you to spin the knob to maximum, then return it to 0 in order to activate the ESC. You will hear a tone when you turn it to maximum and when you return it to 0, so wait until each tone is complete before moving on.

Motor 1 and 2 should spin counter-clockwise (CCW) and Motor 3 and 4 should spin clockwise (CW). If the motor is spinning in the wrong direction, swap the left and right wires from the motor to the ESC. Once the direction is confirmed plug Motor 1’s ESC servo connector to Port 1 of the Pixracer. Repeat this for ESC 2, 3 and 4.

Cable Management

Once you have confirmed the wiring is correct according to the diagrams, clean up the wiring and make sure everything is cable tied and secured.

Propeller Installation

I recommend doing this when you are ready to take your first flight.

In your propeller package you will have a set of propeller shaft adapters. Find one that fits on the shaft of the motor. Break it off and place it on the motor shaft.

Attach a CCW propeller to Motor 1 and Motor 2. Place the propeller over the propeller shaft adapter so that the text of the size of the propeller is facing upwards. Or, make sure the sharp edge of the propeller or the trailing edge is on the bottom.

Place the washer over the propeller so that the flat side is in contact with the propeller.

Thread a nut on the shaft and tighten it until it makes contact with the washer and propeller. When the resistance increases, tighten for another quarter of a turn.

Repeat the process for Motor 3 and Motor 4 using the CW (L) propellers.

Setting And Binding The Remote

If it’s your first time using a receiver and remote you will need to make a profile for your quadcopter on your remote, then map each control to a channel. Bind the receiver to the remote so they can communicate with each other.

Each combo has their own set of instructions for setting up, so please read the instructions provided by the manufacturer. If the instructions are confusing, most popular brands also have YouTube videos to help you set them up.

Congratulations! You have put together your first quadcopter!

Now it’s time to configure the quadcopter and take it for its first flight.

NEXT: PART 3: Software & Setup

PART 1: The Basics

PART 4: Repairing Your Drone

PART 5: Advanced Flight and Autonomous Missions

PART 6: Understanding Brushless Camera Gimbals