Embedded-Screw Knob Handles (All Metric Sizes)

Intro

Turn ordinary metric screws into strong, ready-to-use handles with this simple 3D printing technique.
These knobs are designed to be printed directly around a hex-head metric screw. The screw shaft protrudes, while the head is fully encased in plastic, forming a solid and durable handle without glue or post-assembly. I designed the model to replace a lost screw in my telescope mount, but it has wide applicability everywhere you need to hand-tighten a screw.

I’ve provided separate STL files for a wide range of metric screw sizes and lengths. Just pick the file that matches your screw, start the print, and insert the screw when prompted — the printer finishes the job by sealing it inside the knob. Perfect for:

• DIY tool handles
• Control knobs and jigs
• Quick fixes where a standard knob isn’t available

Model Selection

I have prepared STLs for every meaningful metric screw size (that is, thread size and length combination). They seem very repetitive, but they save you a lot of manual setting in your slicer. Go and just choose by the size of your screw, like M5×40, and so on.

If you have special requirements, or feel handy with the slicer, you can choose the length-agnostic model from the handle_only directory.

Printing

There are two important things you need to set in your slicer: supports and pause.

Supports

If you are using a specific screw size, including length, your model has a disc at the bottom that sets the height and blocks supports from interfering with the screw. Select Support on build plate only and you will be fine.

Print Pause

You have to schedule a pause in the print before the screw cavity gets covered. See the picture below.

Every slicer has a feature to do this. In prusa-slicer, uncover the top layers to show exactly the one above the cavity, then right-click the + sign and select Add Pause.

When your model prints, the printer will stop before the selected layer, and you will be able to insert the screw shaft first into the handle. Then have the printer resume and it will cover the screw head with additional layers, locking the screw in.

Other Slicer Settings

• Printing at 0.2 mm layer height s completely all right
• It is advisable to add perimeters. I use 4.
• Material is up to you. Even PLA is good, PETG is great.
• I use default 15-% infill. I would make the print denser if I were worried about handle durability, but for now it seems adequate.