3D Printable Precision Soft Object Gripper

3D Printable Precision Soft-Object Gripper

This is a fully 3D-printable robotic gripper designed to provide controlled and gentle gripping of both rigid and delicate objects. The gripper uses TPU at the gripping contact points, allowing it to conform to the surface of soft objects and reduce the risk of slipping or damaging them. This makes it suitable for applications such as gripping eggs, lightweight components, laboratory objects, food items, and other delicate parts.

The gripper is powered by a DC motor, while the mechanism can also be adapted to use a stepper motor when higher positioning precision and repeatability are required.

The motor drives a threaded M3 lead-screw-style mechanism. As the motor rotates the screw, the captive nut travels linearly along the screw. This linear motion is transferred through the linkage mechanism to open and close both gripper fingers.

Key Features

• Fully 3D-printable mechanical components

• Designed for soft and delicate objects

• TPU gripping surfaces provide flexible and non-slip contact

• Can grip objects such as eggs without requiring rigid metal jaws

• Powered by a DC motor

• Can be adapted to a stepper motor for improved precision

• Linear motion generated through a threaded M3 screw and nut

• Compact mechanical linkage system

• Suitable as a robotic-arm end effector

• Modular construction for easy assembly and maintenance

• Motor and drive screw can be replaced according to the application

• Designed around commonly available M3 and M4 hardware

Specifications

Required Hardware

The mechanical parts are designed to be 3D printed, with only standard hardware and a motor required for assembly.

Hardware:

• M3 × 15 mm bolts — 18 pcs

• M3 anti-slip/lock nuts — 18 pcs

• M3 × 12 mm bolts — 4 pcs

• M3 × 18 mm bolts — 4 pcs

• M3 hex nuts

• M4 × 10 mm bolts

• M4 spacers — 30 mm height

• DC motor or compatible stepper motor

• M3 threaded bolt/screw — approximately 40–60 mm

• M3 anti-slip/lock nut for the actuator mechanism

Note: The exact motor dimensions should be selected according to the motor mount used in the particular assembly.

Recommended Printing

For the structural parts, PLA, PETG, or ABS/ASA can be used depending on the required strength and operating environment.

For the gripping/contact components, TPU is recommended because its flexibility provides better contact with curved and delicate objects.

Recommended starting settings:

• Layer height: 0.2 mm

• Infill: 20–40%

• Walls: 3–4

• Structural parts: PLA/PETG

• Contact pads/fingers: TPU

These are starting recommendations and can be adjusted depending on the printer and required strength.

How It Works

The motor rotates the M3 threaded screw, causing the nut to travel along the screw. This converts the motor's rotary motion into controlled linear motion. The moving linkage then drives the two gripper arms simultaneously, producing the opening and closing motion.

When TPU contact surfaces reach the object, they provide a soft, high-friction interface, allowing the gripper to hold delicate objects with less concentrated force than a rigid jaw.

For applications where precise positioning is important, a stepper motor can replace the DC motor, providing more controllable movement and repeatability.