Tentacle Arm
A string-driven arm — school physics project
LOADING MODEL… A string-driven articulated tentacle arm, built as a school physics project to demonstrate tension, moments, and mechanical advantage. Stacked segments taper along the arm and thread onto a central carrier, so the whole assembly curls when the internal strings are pulled.
The arm is designed to grab things. Pulling the strings curls the segments inward so the tip wraps around an object and holds it, then releasing the tension lets the arm straighten and let go — a gripper with no motors and no hinges.
It is a soft-robotics-style mechanism made entirely from rigid FDM parts and string tension. Every vertebra and connector was modelled in Onshape to print without supports and assemble by hand — taken from a first prototype through three iterations to a working final arm.
- 01 Prototype 1 ↓ .zip
The first proof of concept — a short stack of segments on a single string, testing whether pulling one string would curl the arm at all.
- 02 Prototype 2 ↓ .zip
Reworked segment geometry and a cleaner string routing. This is the stage where the mechanism actually held its curl — the clip shows it moving.
Mechanism test - 03 Prototype 3 ↓ .zip
Tapered the segments along the length and tightened tolerances so the parts print without supports and slide together by hand.
- 04 Final — Tentacle arm project ↓ .zip
The finished arm: a full taper of segments on a central carrier, print-ready as a 19-part set that assembles into the complete tentacle.