Save Your Fingers, Woodworker: The SawStop
By Chuck Cage
When we first heard about the SawStop, we were doubtful. A table saw that actually stops when you get a finger caught in the blade? Impossible.
Well, apparently not. The SawStop induces an electrical signal onto its special blade and then monitors that signal for changes caused by contact with the human body. SawStop says:
The human body has a relatively large inherent electrical capacitance and conductivity which cause the signal to drop when a person contacts the blade. Wood has a relatively small inherent capacitance and conductivity and does not cause the signal to drop.
When the SawStop detects such a drop, it sends a surge of electricity through a fuse wire, which burns and releases a spring-driven block of aluminum (a “brake pawl”) into the teeth of the blade to stop it from spinning. Simultaneously, the system shuts off power to the motor and the saw’s angular momentum causes the blade to retract below the table.
The result: the blade stops in 3-5 milliseconds, turning what could have been a severed finger into just a nick.
The whole brake and fuse mechanism is contained in a cartridge which must be replaced — along with the blade — after each “emergency stop.” Pricing for the SawStop 10” cabinet saw is $2,799, and replacement cartridges run from $60 to $89. Sure, that’s not cheap, but compare it to a trip to the ER and possibly lost fingers.
There’s a lot more information about this system on the SawStop website (including a cool video of them simulating finger contact with the spinning saw using a hot dog), and we’ll definitely bring you more on this subject soon.
The SawStop Table Saw [SawStop]
August 14th, 2006 at 2:51 pm
[...] We mentioned SawStop’s skin-sensing auto-stop table saws a while back, but we weren’t aware of the ongoing legal wranglings going on in the industry as a result of their product introduction until today. [...]
February 23rd, 2007 at 11:22 am
My wife is a RN, and she will not concent to me purchaseing any table saw other than the SAWSTOP. I do not care about the cost of a new blade/cartrige if it means I keep my hand.
May 9th, 2007 at 11:25 am
[...] Mel recommends the Sawstop, a table saw that actually stops fast enough to avoid damage when you get your finger caught in the blade. It works by measuring capacitance and conductivity, and it actually works. We were blown away when we originally wrote about it, and we later followed up with an interesting link to Sawstop’s alleged “battle against the industry.” It’s all great reading, and it appears to be a truly valuable product. [...]
June 27th, 2007 at 11:35 am
[...] And we discovered the famous/infamous hot-dog-saving SawStop table saw. [...]
April 8th, 2008 at 2:09 pm
I am an amateur woodworker who has been using a 1956 vintage deWalt for a very long time. I bought the Sawstop cabinet saw about a year ago and it has proven to be the finest piece of equipment I have ever owned (including the overpriced Swiss Watch I received as a gift a few years ago). Everything is straight and true and easy to use. I paired it with an Incra fence and I never need to measure before I cut. I just set it and go. I needed to rip some maple strips for molding the other day and so I locked the fence, ripped the wood and then measured. I found that the end result was within .001 in. The saw has lots of power, the table is flat and accurate and the blades are easy to change. Changing the cartridge from single blade to dado takes about a minute. I highly recommend this saw.