eli5. How do table saws with an auto stop tell the difference between wood and a finger?

Question

eli5. How do table saws with an auto stop tell the difference between wood and a finger?

In: 6214

Answer 1

In a similar way a modern touch screen can tell the difference between a finger and a finger with a glove on it: Capacitance.

Or, like you’re 5, the way electricity flows on what is touching the saw blade.

Flesh has a unique enough interaction with electricity that can trip a sensor fast enough to stop a spinning saw blade before a deep cut happens.