Complete Step-by-Step Assembly Guide

This guide walks you through the full build of the ClawBot, a 3D printed robotic arm driven by three servos and an Axiometa Genesis Mini.

The goal is not just to bolt printed parts together.
The goal is to build an arm that:

• Centers its own servos before assembly, no trim pots, no code to write
• Moves on three axes, shoulder, elbow and gripper
• Shows what it is doing on its own display
• Runs from a single USB-C cable
• Can be reprinted and rebuilt any time

Follow the steps in order. The board and the sketch come first, because all three servos get centered before a single one goes into the arm. That is what gives every joint its full range.

NOTE: The ClawBot runs on the Axiometa Genesis Mini with four snap-in modules. The firmware is a free Axie Studio project, so there is no code to write.

The Parts

3D printed parts

• Full ClawBot V1 model, ready to slice: ClawBot-V1.stl
• CAD source file if you want to modify it: ClawBot-V1.step
• 3 printed pinion gears, 2 claw jaws, claw body, base frame with two legs, upper arm, forearm and cover plates

PRINT SETTINGS: filament, layer height and orientation to be confirmed before this guide goes live.

Electronics

• Axiometa Genesis Mini
• Rotary Encoder Module (Port 1)
• Servo Adapter (Port 2)
• IPS LCD Display 0.96" (Port 3)
• Button D-Pad (Port 4)
• USB-C cable

Motion

• 3x MG90S metal gear servos, one per joint

Hardware

• 3x servo horn screws, one per servo, supplied with the servos, used for the pinion gears
• 6x servo mounting screws, two per servo, supplied with the servos
• 8x M3 x 6 hex button head screws for the printed assembly

Tools

• Small Phillips screwdriver
• 2 mm hex driver for the M3 screws
• Hobby knife or flush cutters for print cleanup

Board and sketch first

Step 1 — Print the parts and clean them up

• Print every part from the ClawBot V1 file. Clean the gear teeth and the pin holes with a hobby knife so nothing binds.
• Test fit each gear pair by hand before any screws go in.
• Set the printed parts aside. The electronics come first on this build.

Printed gears carry every bit of load here. Two minutes of cleanup is the difference between a smooth arm and a chattering one.

Step 2 — Snap the modules onto the Genesis Mini

• Rotary Encoder into Port 1.
• Servo Adapter into Port 2.
• IPS LCD Display into Port 3.
• Button D-Pad into Port 4.
• Press each module straight down until the headers are fully seated.

The sketch expects the modules in these exact ports. Swap two and the arm will look dead even though every part works.

Step 3 — Load the ClawBot sketch from Axie Studio

• Open the ClawBot project in Axie Studio: studio.axiometa.io ClawBot.
• Connect the Genesis Mini to your computer with a USB-C cable.
• Flash the project to the board.
• When it boots you should see ROBOTIC ARM on the display with SHO, ELB and GRP listed underneath.

The sketch is what centers the servos in the next step, so it has to be on the board before a single servo goes into the arm.

Step 4 — Center all three servos before you build anything

• Leave the board powered with the sketch running.
• Plug a bare servo into the Servo Adapter. It snaps to its center position.
• Unplug it and repeat for the other two servos.
• Do not turn a centered servo horn by hand after this.

This is the step that makes the whole build work. A servo centered before assembly has equal travel in both directions, so every joint you build around it ends up with its full range. Center them after assembly and one axis will run out of room halfway through a move.

Step 5 — Fit the pinion gears to the centered servos

• Press a blue pinion gear onto each centered MG90S output shaft.
• Lock each pinion down with the servo horn screw that came with the servo, one per servo, three total.
• Do all three now so the rest of the build is pure assembly.

The pinion is the servo horn on this build. Seating it fully on the splines stops it stripping out later under load, and fitting it while the servo is centered means the gear starts at mid travel.

Build the arm

Step 6 — Assemble the claw jaws

• Set the two jaw halves next to the claw body so the gear teeth face each other.
• Drop the first jaw onto its pin and secure it.
• Mesh the second jaw into the first, then secure it the same way.
• Work the jaws open and closed by hand. They should move with no grinding.

The jaws are a matched gear pair, so both sides move together from one servo. Mesh them before tightening, otherwise the jaws close crooked.

Step 7 — Build the base frame

• Lay out the turret piece and the two base legs.
• Slide each leg into its slot on the crossmember until it bottoms out.
• Check the finished base sits flat on the bench with no rocking.

The base is the only thing holding the arm still while it reaches. A flat, square base keeps the whole robot from walking across the table.

Step 8 — Install the shoulder servo

• Drop a centered servo into the base frame with the pinion facing the gear cutout and the lead exiting toward the back.
• Fix it with two of the servo mounting screws that came with the servo.
• Snug the screws only. Do not crank them.

Every servo in the arm mounts the same way, two screws through the servo tabs into the printed bracket. Overtightening pulls the bracket in and binds the gear.

Step 9 — Add the shoulder gear and upper arm

• Fit the large printed gear into the upper arm bracket.
• Mesh that gear with the shoulder servo pinion with the arm sitting halfway through its travel.
• Secure the gear with an M3 x 6 hex screw and check the joint swings freely by hand.

The servo is centered, so meshing the arm at mid travel gives it the same reach forward and back. This is also the first big reduction in the build, a large gear on a small pinion turning a small servo into enough torque to lift the forearm and claw.

Step 10 — Install the elbow servo

• Set the second centered servo into the upper arm bracket, pinion toward the next gear.
• Fix it with two servo mounting screws.
• Feed the lead along the arm as you go so it does not get trapped under the gear.

Routing the lead now saves pulling the joint apart later. The arm has just enough clearance for the wires if they run along the inside of the frame.

Step 11 — Add the forearm gear

• Mesh the forearm gear plate onto the elbow servo pinion, again at mid travel.
• Secure it with an M3 x 6 hex screw.
• Swing the forearm through its full travel by hand and confirm there is no tight spot.

Checking travel by hand before power tells you the mesh is right. A servo will happily push through a bind and strip a printed tooth.

Step 12 — Install the claw servo

• Drop the third centered servo into the forearm bracket with the pinion facing the claw end.
• Fix it with the last two servo mounting screws.
• Leave the claw itself off for now.

The claw goes on last so the jaws can be meshed half open against a centered servo, which gives the gripper room to both open and close.

Step 13 — Route the leads and close up the arm

• Gather all three servo leads and run them down the arm toward the base.
• Fit the side cover plates over the joints.
• Move every joint through its range once more. Anything that catches gets fixed now, not later.

Tidy leads keep the arm out of its own way. A lead pinched in a joint is the most common cause of a stiff axis on this build.

Step 14 — Attach the claw

• Mesh the claw assembly onto the claw servo pinion with the jaws about half open.
• Secure it with an M3 x 6 hex screw.
• Open and close the jaws by hand one last time.

With the claw on, the mechanical build is finished. From here it is all board work.

Bring it to life

Step 15 — Mount the board stack on the base

• Set the Genesis Mini and its modules onto the printed base.
• Fix the stack down with M3 x 6 hex screws.
• Keep the USB-C port clear of the printed frame.

The base doubles as the electronics housing, which is what keeps the ClawBot a single piece you can pick up and carry.

Step 16 — Plug the servos into S1, S2 and S3

• S1 is the gripper, the longest lead.
• S2 is the elbow, the medium lead.
• S3 is the shoulder, the shortest lead.
• Tuck the slack down through the base so nothing rubs on a gear.

The leads are cut to length for their joints, so sorting them longest to shortest lands each servo on the right channel without tracing a single wire. The gripper is furthest from the board, the shoulder is closest.

The longest wire goes to S1.
Medium length goes to S2.
Shortest length goes to S3.

Step 17 — Power it up and drive it

• Plug in USB-C.
• The display shows the three joints, SHO for shoulder, ELB for elbow and GRP for gripper, each with its own position bar.
• Use the rotary encoder and the D-Pad to drive the arm.
• If a joint feels sluggish, back off the M3 screw on that joint a quarter turn. Every joint should turn freely by hand with power off.

A standard USB connection runs all three servos on this build. The one thing that will make it struggle is overtightened M3 screws squeezing the joints.

Print it yourself

The full model is free to download and print: ClawBot-V1.stl, with the STEP source file there too if you want to modify it. The four modules and the Genesis Mini are available at hackmakemod.com, and the firmware is a one click flash from Axie Studio.