3D Printed 3-Jaw Chuck With Planetary Gear System

🛠️ Introduction

In this project, I designed and built a functional 3-jaw chuck that uses a planetary gear system to achieve synchronized motion of all three jaws. This mechanism provides a compact, efficient, and elegant way to grip cylindrical or symmetrical objects — all made with a standard 3D printer.

It's ideal for educational demonstrations, light-duty gripping tasks, robotics, and hobby CNC machines.

Supplies

1. 3D printer (FDM, PLA/TPU compatible)
2. PLA & TPU Filament
3. M4/M5 bolts
4. Allen key or screwdriver
5. Feviquick
6. Sandpaper or deburring tool
7. Lubricant (e.g., silicone grease, optional)

📐 Step 1: Design Overview

The chuck uses a planetary gear system for synchronized motion:

1. A central sun gear turns all three planet gears, each attached to a sliding jaw.
2. The ring gear holds the planet gears in place and translates their rotation into linear jaw movement.
3. As the sun gear rotates, the jaws move inward or outward equally.

Print all the files given in the following Printables/ Thingiverse link.

https://www.thingiverse.com/thing:7052186/files

🧩 Step 3: Assembly

1. Insert the Jaws into their placeholders in the cover.
2. Insert the spiral plate into the cover from the opposite end.
3. Rotate the spiral plate to make sure all the jaws are in proper position.
4. Place the Planet Gears onto the studs in the Spiral plate.
5. Place the Sun Gear in the centre of all the planets.
6. Make sure the Sun Gear is properly meshing with the planets.
7. Place the Cover Plate on top.
8. Secure using M4 bolts.
9. Additionally you can apply a small amount of grease to ease the movement of the system.
10. Mount a Motor onto the back side of the sun gear

🧪 Step 4: Testing and Use

Test the chuck with a variety of objects:

1. Diameter range: ~30mm to 70mm
2. Maximum safe grip weight: ~250 grams (depends on print material and fit)
3. Use it to hold cylindrical parts, tubes, bottles, or tools

Check:

1. Smoothness of motion
2. Symmetry of jaw alignment
3. Load resistance (apply gentle force or hang weights)

✅ Conclusion

This planetary gear-based chuck is a fully functional mechanical system with real-world utility. It demonstrates engineering principles such as gear kinematics, force transmission, and parametric design.

It’s a perfect project for:

1. Mechanical engineering students
2. 3D printing enthusiasts
3. Robotics hobbyists
4. Makers looking to build functional tools

Feel free to remix or improve the design — and share your creations!