The Magic Behind SawStop: How They Work (And Keep You Safe)
For people already familiar with the world of power tools, you've likely heard all about SawStop table saws. If you haven't, SawStop saws are able to automatically detect when an appendage is about to be cut by the spinning blade of a table saw, and a mechanism forcibly retracts the blade and stops it from spinning, preventing injuries or amputation. It may seem hard to comprehend that a tool as simple as a table saw can detect your finger in the way, but it's really the basic principles of electricity that make the SawStop work.
According to SawStop, the blade is fed a harmless electrical current that, when making contact with the electrically conductive human body (i.e. your hand pushing a piece of wood), changes current. That subsequent change in current is detected by the SawStop's braking mechanism to stop the blade from spinning. Instead of a car's caliper and rotor-based mechanism that's meant to be used again and again, the SawStop's brake is a one and done deal.
Safety is expensive
The spring-loaded aluminum brake arm slams itself into the path of the blade, stopping it dead. Simultaneously, the blade drops safely away. SawStop says that it's able to do this by dumping all of its kinetic energy downward. Reportedly this happens in about five-thousandths of a second — near instantly. The brake itself is damaged, and there's a slight possibility the blade is trashed as well, but, more importantly, you have all the fingers you walked into the wood shop with. Once the blade is recovered, you're able to replace the brake "cartridge," which starts at $99.
SawStop table saws aren't cheap, however. The least expensive compact tablesaw from the company, starts at $899 and the most expensive cabinet saw model starts at $4,715. Meanwhile, a DeWalt compact table saw starts at around $400, depending on the model. SawStop does its best to justify the steep price because it would cost less than losing an appendage. And it's hard to argue with that logic, even if nearly five grand on a saw is tough to swallow.