Wavelock Plastic Pet Gate Hinge

The Gate That Knows When to Quit

A three-piece hinge and receiver set for expanding plastic baby and pet gates—built with a little gravity, a little geometry, and just enough mechanical spite.

The hinge rides on a wave-shaped pin. Open it less than 90°, and the gate rolls itself closed like it remembered the stove was on. Push it fully open, and a tiny notch catches the crest, holding it at 90° until you tell it otherwise.

That 5 mm bore lets you drive a steel pin, rod, bolt, or other suspiciously cylindrical reinforcement through the hinge axis. It stiffens the joint, spreads the load, reduces wear, and gives the plastic a metal spine when things get rowdy.

The receiver gets stranger: two print-in-place locking arms hang from a pin buried straight through the body—geometry born for FDM, impossible to assemble because it never needed assembling. Drop the arms and the gate can’t casually swing either way. Tiny plastic bouncers guarding the door.

It doesn’t automatically lock itself yet. Taravangian had brilliant days and stupid days; apparently this was Tuesday.

Print it. Break it. Improve it. Save it for the day your gate starts acting like it owns the house.

A hinge with memory, a latch with teeth, and no batteries to die when you need them. 

DIY prototype hardware—not a certified child-safety device. Test the print, material, mounting, and load before trusting it with anything precious.