This probably needs some explanation.

First! This is not a lock in the conventional way. It does not increase the overall security, but prevents people having a key from entering.

It is more an adapter to turn a bi-directional door lock into an uni directional door lock.

In simple words, if you place this bracket from the inside, no one can unlock the door from the outside using a key. From the outside it looks like the key does not fit anymore, as it is impossible to turn it.

I am not a lock expert and have no clue how the internals work, but on my door the key on the inside rotates if you turn the key on the outside. (dual cylinder lock?) This is the requirement to use this bracket. It simply fixates the key on the inside, so you cannot turn another key on the outside.

Once you slipped it over the door handle, you plug in the key from the inside. The slot in the bracket allows to insert it, but not to turn it. Push the black handle on the bracket upwards and you are able to turn the lock from the inside as normal. This allows to lock/unlock the door without removing the bracket.

Once the door is locked using the key, move the bracket down and the slot prevents the key from being turned. From the inside as well as from the outside. No one with a key can now open the door from the other side.

The source file is included, so you can adapt my design for your door/handle/key dimensions if needed, but it is not that complicated to design it from scratch. In fact this is some old design I made over a year ago, when I started using FreeCAD. I suggest using a simple hard paper mask as a prototype and design the final design on that later on.

WARNING: Do not leave and lock the building having a key and the bracket installed on the inside. Even if you can lock the door, the bracket may slide down onto the key later on and you are locked out. If you want to keep the key inside and the bracket mounted, then push the bracket sideways and plug in the so it is not embraced by the adapter.

I am not responsible for you being locked out. :D.

Print Settings

Printer:

Anet A8

Rafts:

No

Resolution:

15%

Filament: Janbex PLA Black

Category: Household