# eli5 why is the guillotine blade diagonal?

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I’m guessing bc of friction

In: Engineering

I feel like basic reasoning can answer this question. Have you ever cut something with a knife? do you just press down or do you move the knife around?

diagonal knife is like moving the knife

The diagonal blade forces a slice cut even when the blade is moving in one direction

A slice is more effective and reliable than a chop for severing the head from the body

Energy efficiency/ratios.  Pretend a neck is a perfect circle 10cm in diameter. A horizontal blade will cut the entire neck once it has travelled 10cm. (Top to bottom)  If the blade is at a 45 degree angle the blade will make first contact on the top right side of the circle and will complete the cut once the blade reaches the bottom left. The blade must travel 14.1cm to complete the cut. So at a 45 degree angle you cut 1cm of neck for every 1.41cm of vertical drop of the blade. It’s like speeding the blade up 41%.

It’s always easier to start a small cut than a large one. Angled blade starts a small cut instead a blunt, across- the-entire-neck cut (basically a chop), though with a heavy enough blade that wouldn’t be a concern with the soft squishy flesh of a human. Pulverized or sliced, dead is dead.

Ever pushed a knife down hard into the middle of a juicy tomato without making a slicing motion?

That’s why.