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Magnetic door lock

Why

The toilet door has to be closed. To keep it closed, a lock is often used. (This door did not have a handle.) However, opening and closing it all the time was a bit tiring, especially when in a hurry or when carrying something to be disposed of.

How

A magnetic holder was chosen as the best available solution. A neodymium magnet salvaged from a hard drive was attached to the side of the door. A steel L-profile was attached on the doorframe, leaving a small air gap so the magnet and the steel-L do not touch.

The Mk.1 was a simple steel L, held in place with one wood screw. However, in the course of years, the considerable force of the magnet made the screw slightly loose and the steel L got tendency to move slightly and come to direct contact with the magnet, and the door required much more force to be opened.

The Mk.2 is an improvement on the Mk.1, as a flat piece of steel is welded to the L and forming a T, with two wood screws holding the stem of the T in place (and absorbing the force exerted by the magnet in a much more resilient way than Mk.1 did).

The air gap was maintained by putting a piece of cardboard between the magnet and the T. The T-part, held in place with the magnet, was then used as a drilling template for guide holes for the screws, then screwed into place.

The lock "catches" the door when it is almost closed, and pulls it into fully closed position and holds it there. The effort of closing the door is therefore limited to pushing (or kicking) the door into closing movement, and if the force was enough to get it almost-closed, the magnet does the rest. (If the force was too high and the door slams the frame, the magnet catches it and prevents its rebounding.) The effort for opening the door is also limited to just gently pushing the door with a foot or a knee or a hand. The magnet has surprising strength and the force can be adjusted by setting the air gap.

Images


Parts, before welding

Parts, prepared for welding

Welded parts

Welded parts

Welded parts

Welded parts

Drilled holes

Magnet on the door

Prepared for mounting

Prepared for mounting

Mounted assembly

Detail of assembly, air-gap visible

Videos


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