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Kit Build​

You have met every part in the box. This page assembles them into the starter Robot: a floating frame on four Hulls, driven by two Underwater Thrusters, with a T Flipper on the front for pushing Hex Links around. It will not win a Match on its own, but it gets your team on the water quickly, and every part of it can be moved, replaced, or thrown away once you have your own ideas.

If a part name below is unfamiliar, look it up in Kit Intro.

Build it in this order. Each stage finishes a sub-assembly that a later stage bolts onto the frame:

  1. Thruster Hulls — two of them
  2. T Flipper
  3. Main assembly — the frame that joins everything
  4. Sensors and cables
  5. Robot Brain battery

Before you start​

The kit includes one double-ended Combination Wrench: 7 mm for M4 nuts, 5.5 mm for M3 nuts. Use the Allen Key Set for the screw heads, and pick the size that fits properly — a loose key will round out the socket.

Wherever a step pairs a screw with a nylock nut, hold the nut with the wrench and turn the screw. Nylock nuts have a nylon insert that grips the thread, so they feel stiff for the last few turns. That is normal, and it is what stops the Robot shaking itself apart in the water.

Screws are named M<thread diameter> x <length>, both in millimetres, with the length measured from under the head. An M4 × 20 and an M4 × 30 drop into the same hole but reach very different depths, so check the number on the bag before you reach for one.

Beams have an odd side and an even side

Look down the face of a beam: one face has an odd number of holes in its row, the other has an even number. Several steps below depend on which face is up, and getting it wrong shifts everything by half a hole. The diagrams call this out where it matters.

1. Thruster Hulls​

Build two of these. They are identical except for the direction their propellers turn.

Parts (per hull)​

Part Quantity From
Thruster Hull (Float Block, thruster version) 1 —
Underwater Thruster 1 Underwater Thruster Bag
Motor Bracket 1 Underwater Thruster Bag
M5 × 8 screw 2 Fastener Box

Parts needed for one thruster hull: one thruster-version float block, one motor bracket and one underwater thruster from the Underwater Thruster Bag, and two M5 x 8 screws from the Fastener Box. A callout notes two hulls are to be assembled.

The two Thrusters are not identical

One Thruster has a Clockwise (CW) propeller and the other a Counterclockwise (CCW) propeller. Fit one of each — one per hull. Two of the same rotation will make the Robot yaw every time you try to drive straight.

Note slide on opposite rotation: the counterclockwise thruster on the left and the clockwise thruster on the right, each with an arrow showing which way its propeller turns.

Steps​

  1. Take a Thruster Hull and set it the right way up, recess on top.
  2. Lay the Thruster into the recess with the propeller facing out. Push it back so it sits flush against the back of the mount — if it creeps forward, the bracket will not clamp it squarely.
  3. Put the Motor Bracket over the Thruster body and fix it with 2× M5 × 8.

Three-step diagram: the bare float block, the thruster laid into its recess with a callout to flush it against the back of the mount, then the bracket fitted over it with two M5 x 8 screws, ending in a completed thruster hull.

You should have: two finished Thruster Hulls, one CW and one CCW. Keep track of which is which — it matters in step 3.

2. T Flipper​

The T Flipper is the starter Robot's arm. A Servo tilts a crossbar up and down to break up scored Hex Links, flip them to your Alliance colour, or shove them around.

Parts​

Part Quantity From
Beam 1x (half) 2 —
Spade Piece 1 —
Servo Arm Connector 1 —
Servo Arm 1 Servomotor Bag
M2 × 8 screw 2 Servomotor Bag
M4 × 25 screw 2 Fastener Box
M4 × 20 screw 2 Fastener Box
M4 nylock nut 4 Fastener Box
M3 × 20 screw 1 Fastener Box

Parts needed for the T Flipper: two half-length 1x beams, a spade piece, a servo arm connector, and from the bags and Fastener Box, a servo arm, two M2 x 8, two M4 x 20, two M4 x 25, four M4 nylock nuts and one M3 x 20.

Optional screws need extra fasteners

Steps 6, 9 and 13 add a second screw to a joint that is already held. They are optional, but the arm is much stiffer with them in. Each one needs a fastener beyond the list above — grab them from the Fastener Box as you go.

Crossbar and spade​

  1. Beam. Lay one half-length 1x beam flat.
  2. Spade. Sit the Spade Piece across the middle of it, on the beam's odd side.
  3. Screws and nuts. Fix it with 2× M4 × 25 and 2× M4 nylock nuts. Tighten with the provided wrench.

Three-step diagram: the bare half beam, the spade piece placed on its odd side, then two M4 x 25 screws dropped through into two M4 nylock nuts underneath, with an alternate view and a reminder to use the provided wrench.

Upright​

  1. Beam. Stand the second half-length 1x beam upright and slide its end into the Spade Piece, even side facing out.
  2. Screw and nut. Fix it with 1× M4 × 25 and 1× M4 nylock nut.

Steps four and five: the upright beam offered up into the spade piece with its even side facing out, then fixed with one M4 x 25 screw and one M4 nylock nut, with an alternate view.

  1. Optional. Add 1× M4 × 30 and 1× M4 nylock nut through the second hole of the same joint for extra strength.

Step six, optional: a second screw, one M4 x 30 with an M4 nylock nut, passing through the other hole of the spade joint, shown from two angles.

Servo Arm Connector​

  1. Servo Arm Connector. Push the connector onto the bottom end of the upright beam, over the beam's even side.
  2. Screw and nut. Fix it with 1× M4 × 20 and 1× M4 nylock nut.

Steps seven and eight: the servo arm connector slid onto the lower end of the upright beam on its even side, then fixed with one M4 x 20 screw and one M4 nylock nut.

  1. Optional. Add 1× M4 × 25 and 1× M4 nylock nut through the connector's second hole.

Step nine, optional: a second screw, one M4 x 25 with an M4 nylock nut, through the other hole of the servo arm connector, shown from two angles.

Servo Arm​

  1. Clamp screws. Thread the 2× M2 × 8 into the Servo Arm's clamp.

    Do not tighten the clamp screws yet

    Thread them on lightly and stop. The clamp has to stay loose enough to slip over the Servo's splined output shaft later. Tighten it now and you will be undoing it in a few minutes.

Step ten: the two M2 x 8 clamp screws threaded into the servo arm, with a photo of the real part and a warning not to tighten them yet because the arm must stay loose enough to slip onto the servo.

  1. Servo Arm. Offer the Servo Arm up to the bottom of the Servo Arm Connector.
  2. Screw. Fix it with 1× M3 × 12.

Steps eleven and twelve: the servo arm brought up to the underside of the servo arm connector, then fixed with one M3 x 12 screw, with an alternate view.

  1. Optional. Add 1× M3 × 12 through the connector's second hole.

Step thirteen, optional: a second M3 x 12 screw through the other hole joining the servo arm to the connector, shown from two angles.

The T Flipper does not go onto the Servo yet

The Servo has to be zeroed in code before the arm goes on, so that the crossbar's sweep lines up with the Servo's travel. You will do that in Your First Program. Until then, set the finished T Flipper aside with its clamp screws still loose.

3. Main assembly​

This is where the sub-assemblies become a Robot.

Parts​

Part Quantity From
Robot Brain 1 provided assembled
Thruster Hull 2 assembled in step 1
Hull (plain Float Block) 2 —
Beam 1x (full) 3 —
Beam 2x (full) 3 —
Servomotor Mount 1 —
Servo 1 Servomotor Bag
M4 × 50 screw 2 Fastener Box
M4 × 40 screw 4 Fastener Box
M4 × 35 screw 8 Fastener Box
M4 × 30 screw 2 Fastener Box
M4 nylock nut 8 Fastener Box
M3 × 12 screw 4 Fastener Box

Parts needed for the main assembly, first slide: one Robot Brain, provided assembled, and two thruster hulls assembled earlier.

Parts needed for the main assembly, continued: three full 1x beams, three full 2x beams, two plain float blocks, one servo mount, one servo, and from the Fastener Box eight M4 nylock nuts, two M4 x 30, eight M4 x 35, four M4 x 40, two M4 x 50 and four M3 x 12.

Front beam​

Lay one 2x full beam down across the front of the build, even side up. Everything else is positioned from this beam, so get its orientation right before you go on.

Step one: a single full-length 2x beam laid flat with a callout reading "Even Side Up".

Centre beams​

  1. Lay two 1x full beams across the front beam, running fore and aft, even side up. Position them at the 5th hole from the left and the 4th hole from the right.
  2. Sit the Servomotor Mount over the left-hand junction.
  3. Fix everything with 4× M4 × 40 and 4× M4 nylock nuts — two screws per junction. Tighten with the provided wrench.

Step two: two 1x beams laid across the front beam with the servo mount at one junction, fixed by four M4 x 40 screws into four M4 nylock nuts, with a top view marking the beam positions as five holes from the left and four from the right.

Aft beam and Robot Brain​

  1. Lay the last 1x full beam across the back of the two centre beams.
  2. Sit the Robot Brain on top, its mounting feet over the beam holes, with the port labels (M1–M8, S1–S6) readable from above.
  3. Fix it with 2× M4 × 50 at the forward feet and 2× M4 × 30 at the aft feet, into 4× M4 nylock nuts underneath.

Step three: the Robot Brain lowered onto the frame, with two M4 x 50 screws at one end and two M4 x 30 at the other passing down through its feet into four M4 nylock nuts, and the result standing on the beams.

Check the hole positions from directly above before you tighten — the Brain should straddle the centre beams squarely, with the same 5 from the left, 4 from the right spacing as the beams themselves.

Top view of the Robot Brain between the two centre beams, with callouts marking five holes from the left and four holes from the right at the front and rear crossings.

Left side​

  1. Lay a 2x full beam along the left side, bridging the front and aft beams.
  2. Bring one plain Hull and one Thruster Hull up underneath it.
  3. Fix each Hull with 2× M4 × 35 down through the side beam — 4× M4 × 35 in total.

Step four: a 2x side beam added along the left of the frame with two hulls below it, fixed by four M4 x 35 screws, and the resulting frame standing on its hulls.

Thrusters face back, and the Hulls are offset

Both Thruster Hulls go at the front with their propellers facing aft — they push the Robot forwards. Set each Hull so there are 3 holes in front of the metal frame at the front position, and 3 holes behind the metal frame at the rear position. Getting this backwards leaves the Robot nose-heavy and driving in reverse.

Hole position slide: a top view showing the front hull sitting with three holes in front of the metal frame and the rear hull with three holes behind it, plus a detail with the thruster facing back and the front of the Robot marked.

Right side​

Repeat step 4 on the right: one 2x full beam, one plain Hull, one Thruster Hull, 4× M4 × 35. Thruster facing back again, so the two propellers point the same way.

Keep the CW Thruster on one side and the CCW Thruster on the other.

Step five: the right side beam fitted with its two hulls and four M4 x 35 screws, with a detail showing the thruster facing back, and the finished frame standing on four hulls.

Servo​

Bolt the Servo into the Servomotor Mount on the front beam with 4× M3 × 12.

Servo orientation

The Servo goes in with its output shaft closer to the front of the Robot, as shown in the detail view. The T Flipper's reach depends on it.

Step six: the servo lowered into the servo mount on the front beam and fixed with four M3 x 12 screws, with a close-up showing the servo oriented closer to the front of the Robot.

You should have: a frame standing on four Hulls, the Robot Brain bolted across the centre beams, and the Servo mounted on the front beam.

The completed main assembly: the Robot Brain on the beam frame, standing on four hulls, with the servo mounted at the front.

4. Sensors and cables​

Parts​

Part Quantity From
IMU Sensor Module 1 —
LoRa Module 1 —
M4 × 30 screw 4 Fastener Box
M4 nylock nut 4 Fastener Box

Telling the two modules apart

The IMU Sensor Module has a black top. The LoRa Module does not. They are the same size and take the same screws, so check the top before you bolt one down.

Parts needed for the sensors: one IMU sensor module, noted as the one with a black top, one LoRa module, and from the Fastener Box four M4 x 30 screws and four M4 nylock nuts.

LoRa Module​

Sit the LoRa Module on the frame beside the Robot Brain, cable gland pointing towards the Brain, and fix it with 2× M4 × 30 and 2× M4 nylock nuts. Tighten with the provided wrench.

Step one: the LoRa module lowered onto the frame beside the Robot Brain and fixed with two M4 x 30 screws and M4 nylock nuts, with the result shown mounted.

IMU Sensor Module​

Mount the IMU Sensor Module on the opposite side of the Robot Brain the same way: 2× M4 × 30 and 2× M4 nylock nuts.

Step two: the IMU sensor module lowered onto the frame on the other side of the Robot Brain and fixed with two M4 x 30 screws and M4 nylock nuts, with the result shown mounted.

Cables​

Plug each device into the port your program will expect. The port names in your code have to match what you physically plugged in.

Device Port
IMU Sensor Module S1
LoRa Module S6
Servo M2
Right Thruster M1
Left Thruster M8

Cabling diagram: a top view of the Robot Brain's ports with the IMU sensor module wired to S1, the LoRa module to S6, the servomotor to M2, the right thruster to M1 and the left thruster to M8.

Screw each connector down finger-tight — they are sealed connectors, and a loose one lets water in.

5. Robot Brain battery​

The Robot Brain ships sealed and empty. Open it once to fit the battery, then close it properly. Everything inside is electronics, and the seal is the only thing keeping the pool out.

Parts​

Part Quantity
Baseplate assembly 1
Brain top 1
Battery 1

Parts for the Robot Brain: the baseplate assembly with its gasket, the brain top with the ports and thumbscrews, and one battery.

Steps​

  1. Orient. Set the Robot Brain upright on the bench.

    Open it upright, never upside down

    Any water sitting on the lid will run straight into the electronics if you open it inverted. Check it is the right way up before you loosen anything.

  2. Unscrew the top half. Loosen the lid thumbscrews and lift the top off the baseplate. Use the Thumbscrew Wrench only for loosening — tightening with it over-torques the screws.

Steps one and two: the Robot Brain held upright with a warning to ensure it is upright before opening, then the top lifted off the baseplate to show the gasket seated in its groove.

  1. Install the battery. Drop the battery into the tray.

  2. Connect the battery connector. The Brain powers up as soon as it is connected.

    Pair with a Controller while the box is open

    This is the easiest moment to pair the Robot Brain with a Controller, because you can still reach everything inside. Follow Extension Walkthrough to connect a Controller and pair the Brain, then come back and close the box.

Steps three and three-point-five: the battery lowered into the baseplate tray, and a photo of a real baseplate with the battery connector plugged in, with a callout to connect the battery and pair with a controller during this step.

  1. Latch the battery. Swing the red latch over the battery so it cannot slide around.

  2. Tighten. Refit the top over the gasket and tighten the thumbscrews evenly by hand.

    Check the gasket before you tighten

    The gasket must sit in its groove all the way round, with no cable pinched across it. A gasket that has popped out of the groove will not seal, and you will not find out until the Robot is in the water.

Steps four and five: the battery latched down in the baseplate, then the top refitted over the gasket and the thumbscrews tightened, giving a closed Robot Brain.

Before you move on​

Your starter Robot is built. Ensure that the electronics are connected to the ports shown in the build guide. If you chose other ports, change the port numbers in the example code respectively.

You should have: a Robot standing on four Hulls, Thrusters facing aft, sensors and Servo wired to the Brain, a closed and sealed Robot Brain with its battery in — and the T Flipper set aside with its clamp screws still loose, waiting for the Servo to be zeroed.

Next: Set up MARLIN on your laptop in Installing MARLIN.