3D Printed Knob with M3 Brass Inserts

Overview

This high-quality, 3D-printed knob is designed for durability and versatility.

It is one of those small parts that ends up needed across almost every mechanical project sooner or later: a hand-turnable grip for a locking screw, a tensioning bolt, or an adjustment mechanism, anywhere a user needs to tighten or loosen something by hand without reaching for a tool. Threading a bolt directly into printed plastic works for a handful of uses, but the threads wear out fast under repeated tightening and loosening, which is exactly the failure mode you run into on any knob you actually turn often.

It features embedded M3 brass inserts, providing a secure and reliable threaded connection for screws or bolts. Heat-set brass inserts solve the wear problem: they are pressed into the print with a soldering iron or a dedicated insert tool, and the resulting metal thread holds up to hundreds of tightening cycles the way bare printed plastic threads never could.

Perfect for applications in DIY projects, electronics, robotics, and mechanical assemblies, this knob ensures a solid grip with its ergonomic design, offering both comfort and precision during use.

The brass inserts guarantee long-lasting durability, allowing repeated assembly and disassembly without wear or stripping of the threads.

Key Features:

3D printed with strong, durable filament (PLA/ABS/PETG).
Integrated M3 brass inserts for enhanced thread strength.
Ergonomic shape for easy handling and firm grip.
Ideal for various projects: from electronics enclosures to custom machine controls.
Available in multiple sizes and customizable designs on OnShape.

A small, reusable building block worth keeping in the back pocket for the next project that needs one.

A humble knob, but one that will still be threading smoothly long after a bare plastic one would have stripped.

Applications:

Use this knob for adjusting tension, attaching parts, or controlling mechanisms in prototypes, machines, or any project where a secure, reliable fastening solution is needed.

I sized this one for a common M3 insert and a compact grip, but the underlying idea, a printed knob body with a heat-set metal thread, scales to whatever bolt size and grip diameter your own project actually needs.

Design:

This model has a total length of 8 mm and a diameter of 7.5 mm and fits M3 heat-set brass inserts. Feel free to customize the model in the public OnShape project.