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Chapter 11 · Building

From box to drone

Building it yourself is the best way to understand how all the parts fit together, and to know how to fix it after a crash.

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Before you solder: plan

  • Dry-fit all the parts on the frame without fixing them: where the stack, camera, VTX and receiver go.
  • Decide where each wire will run and where the antennas will come out.
  • Look at where the battery will sit and check that the centre of gravity falls in the middle of the frame.
  • Keep the flight controller and ESC wiring diagrams to hand.
  • If it’s your first build, go over Tools and soldering.

The first battery connection, always with a smoke stopper. Before that, check with the multimeter that there’s no contact between positive and negative. And never test anything with the props on.

Typical layout of a 5-inch seen from above: camera at the front, stack in the middle, video transmitter and receiver at the back, antennas pointing backwards and the battery on top, centred over the centre of gravity STACKCamera, at the frontStack, in the middleBattery on top, centredVideo transmitterELRS receiverAntennas backwardsFRONT● centre of gravity
Dry-fit everything before soldering. The centre of gravity must sit in the middle, between the four motors.

The eight steps

  1. Assemble the frame

    Threadlocker on every metal screw that doesn’t go into a nylon lock nut. If there are sharp carbon edges that could strip wires, file them down.

  2. Mount the motors

    The screws must leave at least 1 mm of clearance to the windings: if they touch them, it’s a short and a burnt motor. Point the wires towards the centre of the frame.

  3. Install the ESC

    With the rubber grommets, not overtightened so they can do their job. Arrow on the board pointing forwards and battery pads at the back.

  4. Solder the motors

    Trim the wires to length, tin pads and wires separately and join them. The order of the three wires doesn’t matter: the spin direction is fixed in software.

  5. XT60 and capacitor

    Mind the polarity (red to positive). The capacitor goes as close to the battery pads as you can: it absorbs voltage spikes.

  6. Test with a smoke stopper

    Before fitting the flight controller. If the bulb stays lit, disconnect and look for the short.

  7. Flight controller, camera and VTX

    Connect the cable between the ESC and the flight controller. Power each peripheral with the right voltage (5 V, 9 V or straight from the battery, depending on the model). Never power up the VTX without an antenna.

  8. Receiver and antennas

    Receiver TX to the RX of a free UART and vice versa, plus 5 V and ground. Antennas away from the carbon and the props, ideally angled or in a V.

Common mistakes

Screws too long

They touch the motor windings and burn it out.

Wires within reach of the props

A dangling wire ends up cut on the first flight.

TX and RX wired wrong

Always crossed: one device’s TX goes to the other’s RX.

Solder bridges

Solder joining two neighbouring pads. Check them with a magnifier.

Tidiness and cleaning

  • Wires short but not under tension, held with cable ties or tape.
  • Clean off flux residue with isopropyl alcohol.
  • Protect the receiver and delicate connections with heat-shrink tubing.
  • Take photos of the wiring before closing the frame: they’ll help when you have to repair it.

With the drone built, the next step is to configure it in Betaflight and go through the pre-flight checklist.