eli5: How do some tablesaw know when to autamatically stop when it is about to cut you?

Question

eli5: How do some tablesaw know when to autamatically stop when it is about to cut you?

In: Engineering

Answer 1

Answer:

It’s not the saw that knows, it’s a seprate part called a SawStop that is installed into the saw housing. The SawStop gives the blade a small electric charge and when your finger (which also has a small electric charge) touches the blade, it completes the circuit and sends a signal to the SawStop to activate. Activation uses a spring loaded mechanism to bring the blade to a stop.

Here’s an explanation and some slo mo footage: https://www.youtube.com/watch?v=SYLAi4jwXcs