Comment by lazide
7 months ago
The sawstop triggers when the blade contacts something conductive (like a finger), and needs to stop fast enough that when that happens the finger isn’t removed first.
It manages to do that within a few teeth, which is quite impressive at 1000+ RPM.
It does this by firing an explosive charge which shoves an aluminum block into the spinning blade, while dropping the blade below the level of the saw deck.
Essentially a type of airbag like braking action.
That is how it can turn s situation which would guaranteed an amputation into a minor scratch.
It can (and does) get easily triggered by things like conductive wood (pressure treated), nails or metal in the wood, metal coated plastic, etc.
Every workshop I’ve been at that has one has a collection of triggered/destroyed blades hanging on the wall.
It could undoubtably be done cheaper than it currently is ($30 a brake?) but as designed it’s destructive - and it’s hard to imagine a effective way to do what it does that isn’t destructive.
The brake is like $80-90 and contains a computer that collects telemetry. If it triggers for a reason other than user error you can send it in for a refund.
It doesn't drop the blade, just stops it cold (at least on the model I've used). The Bosch system dropped the blade (thereby avoiding destructive damage to the blade and brake) but they were cease-and-desisted by SawStop and unable to sell it in the US.
The one I used, and their website, says that they drop the blade. [https://www.sawstop.com/why-sawstop/the-technology/], but I’m not clear on all the models. It’s been years since I’ve used one. Glad they’re cheaper now!