Huge demo handcuff

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I was called upon recently to teach some handcuff escape workshops. In keeping with my tendency to build large demonstration props, I decided to construct a huge, functioning, see-through handcuff.

Here you can see the ratchet and pawl mechanism at work. This allows the cuff to tighten, but not open.

I designed them in Rhino, cut the layers of acrylic on a laser cutter, and formed the spring from a street sweeper blade using heat and pliers.

The key works by rotating around the keyhole post, lifting the pawl high enough to slip the ratchet.

Don’t have a key, but need to get the cuff off? Shimming works by inserting a thin piece of metal in above the ratchet, closing the ratchet a few clicks tighter, enough to slide the shim under the pawl. At this point, the ratcheted cuff swings free.

Handcuffs typically include a double lock feature which prevents the cuff from tightening once engaged. Shimming doesn’t work on cuffs that have been double locked. I may build a future version of the huge handcuffs that incorporate this feature.