KeyKeep Door Knob Adapter

The KeyKeep Door Knob Adapter is a practical 3D-printed solution designed to keep a door key permanently attached to German interior doors. It was developed and tested for Hörmann steel doors, but it can also be used with many other doors that use a similar knob/knob-cylinder setup, with minor adjustments if needed. It’s especially useful for workshop toilets, storage rooms, or shared spaces where keys tend to get misplaced.

The adapter holds the key securely at the door knob so it is always available when needed, while still allowing comfortable operation of the lock. The design is compact, durable, and easy to assemble, making it suitable for everyday use.

Printing instructions:
Print the parts in the orientation shown in the model preview. Use a 0.2 mm layer height, and no supports are required. Standard infill (e.g., 15–25%) is sufficient for most materials. PLA, PETG, or ABS can be used depending on your strength and temperature requirements.

Assembly notes:
For easier assembly, the two parts that clamp around the key can be temporarily aligned and held together using small pieces of 1.5 mm² square copper wire inserted into the triangular holes near the key area. This helps keep everything in position while fitting the adapter onto the knob.

After final assembly, place two small drops of superglue from the back into the key holder section of the knob. This prevents the components from sliding apart when pulling on the knob and ensures a secure, long-lasting fit.

Additionally, it is recommended to press a small piece of foam into the back of the key holder. This keeps the key under slight forward pressure inside the lock so it always stays properly seated. The gentle tension prevents the key from sliding back, which helps avoid sticking or jamming during use.