SG90 Parallel Robot Gripper Claw – 60mm Opening

A compact, servo-driven parallel gripper for DIY robot arms, pick-and-place rigs and Arduino/ESP32 projects. One SG90 micro servo turns a center pinion that drives two geared racks, so both jaws always move together, stay parallel and close on the center line. Objects stay centered no matter their size, and the flat jaws grip blocks, balls, cells and other small parts securely.

 Everything bolts together with four M3 screws into heat-set inserts, so it is easy to take apart, re-tension or swap a finger. The rear wrist plate gives you a clean interface for mounting it to your arm.

 Features

• Parallel jaws with a 60 mm maximum opening

• Rack-and-pinion drive (24-tooth, module 0.7 pinion) – both jaws are synchronized and self-centering

• About 26 mm of travel per jaw for 180° of servo rotation, so a standard SG90 closes it to roughly 7–10 mm

• Large flat jaw faces (about 33 × 36 mm)

• Protective housing around the servo

• Rear wrist mount with an 8 mm center bore and two M3 clearance holes (17 mm apart), designed to carry an angle sensor

• Assembled size about 76 × 82 × 40 mm (fully open)

Printed parts (6 pieces)

• Rail base ×1

• Servo housing (base plate) ×1

• Finger ×2 (identical)

• Spur gear ×1

• Wrist mount / angle sensor holder ×1

Hardware

• 1× SG90 9 g micro servo (with its horn screw)

• 4× M3 × 35 mm button-head hex socket screws

• 4× M3 heat-set inserts, 5 mm OD

Suggested print settings

• Material: PLA or PETG (PETG for the gear and fingers if it will see heavy use)

• Layer height: 0.2 mm (0.12–0.16 mm for the gear gives smoother teeth)

• Walls: 3–4 perimeters, infill: 25–40 %

• Print each part on its largest flat face

Assembly

1. Press the four M3 heat-set inserts into the wrist mount with a soldering iron.

2. Drop the SG90 into the servo housing and route the cable out.

3. Center the servo (90°) with your controller, then fix the spur gear to the servo output with the servo's screw.

4. Slide both fingers into the rail base so their racks mesh with the gear at the same opening on each side.

5. Stack the rail base, servo housing and wrist mount, then clamp everything together with the four M3 × 35 screws.

6. Test the open and closed positions slowly and set your servo limits in code so the jaws don't stall against each other or the end stops.

Tips

• Add a strip of rubber, TPU or grip tape to the jaw faces for better grip on smooth objects.

• Limit the closing angle in code instead of letting the servo stall – the SG90 heats up quickly when blocked.

• A metal-gear MG90S usually shares the SG90 footprint and is a good upgrade for more durability.

Files

STEP file of the full assembly (printed parts plus servo and fastener models for reference).

Questions, makes and remixes are welcome – please post a make if you build one!