Secret Locking Mechanism

I have not been doing a lot of flat work lately – instead, I’ve been focusing on turning. However, an officemate recently asked me to make a box for his nephew. The only requirement: some sort of secret locking mechanism.

This is what I cam up with. It’s primarily rock maple, with a bubinga inlay in lid and used for miter keys. Overall dimensions are around nine inches wide, seven inches deep, and five inches tall. The locking mechanism is fairly standard – a catch in the front base rotates and engages a bar in the front lid. Generally, the catch is operated by a key that is inserted into the top. In this case, there is no key hole. And the key itself is integrated into the box.

Notice the catch is in the locked position in the third picture (the lid would typically be closed when the catch is in the locked position, but that would make it awfully difficult to photograph). How does it operate, you ask? Magnets.

The bottom of the catch has a magnet attached. The inside of the mortise has two tiny magnets at both the open and locked positions – these are attracted to the catch’s magnet and hold the lock in one of those two positions. By using a more powerful magnet to overcome the positioning magnet, the catch can be moved between the two positions. Where might we find a more powerful magnet? It happens that the necessary magnet is holding the handle on to the lid. Once removed, it acts as the magnetic key.

I tried describing this mechanism on one of the woodworking forums I frequent, and there was a bit of confusion. I threw together a quick cutaway diagram of the mechanism, which helped most figure out how it worked. For those who still had problems, I shot a quick video with my phone. Both are shown below.

 

Leave a Reply