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Seek and Geek 1: Soft Close Drawer Slides

While cooking dinner, I accidentally bummed my kitchen drawer closed a lot harder than intended. I winced in anticipation of a loud slam that never came. Surprised, I started playing with my cutlery drawer. After a few moments of shoving my drawer back and forth and then eventually removing the drawer altogether, I found this interesting mechanism in the glide rails:

The mechanisms dampers the last few centimeters of drawer travel. Damping this motion rapidly decelerates the drawer, preventing wear and, more importantly, preventing loud collisions when the drawer is closed.

The central element in the mechanism is shown below. It was obvious that the white cap holds a magnet which 'catches' the drawer by a metal protrusion on the guide rail, however it was unclear how the damping was achieved. Hesitant to break the device open and intentionally damage my drawer, I was unsure of how the component functioned. While playing with it, I noticed that the travel of the white cap had differing force profiles when extended vs. compressed. During extension, there was minimal resistance, however during compression there was a notable opposing force that increased with increasing load.

The force profile excluded simple springs and dashpots, which would react symmetrically in extension and compression. While brainstorming on the device's inner workings, I found that a slow leaking piston and one-way valve could supply the observed force. During extension or opening of the drawer, the check valve would allow air in easily, allowing minimal resistance to travel. Then during compression or closing of the drawer, the piston would compress air and the leak rate of the piston would determine the speed at which the drawer traveled.

To verify my findings, I plan to go to Home Depot and find a similar soft close rail to take apart. Before dismantling, I will submerge and actuate the piston component in water to observe the rate at which air bubbles exit the housing during operation. I would test this out on my own pistons but I fear they would rust and my drawers would lose their gentle glide.

Keep your eyes peeled for an update!