SawStop GIF

[Jon]

SawStop GIF.

This is the type of table saw that is marketed as stopping as soon as you accidentally cut your finger. I've never used one, but I know that they work by monitoring the difference in electrical conductivity between wood and human flesh. A small amount of voltage is applied to the blade, and the current is continuously monitored. Once a change in this current is detected, a braking block is forced into the saw blade.

After various licensing battles involving tool companies and the SawStop inventor, an amateur woodworker and physicist named Steve Gass, this same technology is now finding its way into other mainstream saw brands.


https://diqn32j8nouaz.cloudfront.net/sawstop.gif

[mklotz]

My understanding is that, when activated, the device destroys itself, the saw blade, and perhaps other bits of the saw in the process of stopping the saw. The cost and time to make the saw operational again is, of course, of no account if it saved someone's digits but might be problematic if the wood is a bit wet or salty.

Secondly, I'm not about to trust my body parts to a bit of electronics that may or may not be working properly when I need it to do its thing. Even on some of the man-rated space stuff I worked on where the consequence of failure was death was it possible to achieve 100% reliability. Kickbacks can inflict serious injury too. The next step will be some electronic gizmo to sense that. Soon the saw blade will be festooned with sensors and devices that will need to have all possible interactions accounted for in a (human coded) program in the onboard computer. Yeah, good luck with having all that fail safe.

Finally, I'm strongly opposed to the current infatuation with having everything done for you so, presumably, you can update your Facebook status while driving, welding, sawing, crossing the street, etc.. If you don't learn to pay attention to what you're doing and practice self-protection it's inevitable that you'll encounter a situation where they haven't yet installed the gadget to save your derrière and you'll join the legion of Darwin Award winners (assuming you have no offspring).

[Jon]

Yeah, still qualifies as "gimmicky". You're spot on about wet wood; the recommendation is to deactivate the brake system for green timber. The concept of using the different conductivity between metal and flesh for increasing safety may have other uses.

The backstory on Gass's scuffle against existing tool manufacturers is interesting. He has a UCSD doctorate in physics, plus a law degree. It sounds like he was in licensing negotiations with Ryobi, but maybe they played the negotiations as a "fishing expedition" - dragging out talks as they gained information and time, while conveniently failing to correct a typographical error in the contracts.

Then the politicians got whiff of the "safety" angle, and started to push on legislation to mandate SawStop-like additions on new saws. No joke, here are some of the bills:

Illinois HB0450 - "Requires a saw manufacturer to retool its production line to install the SawStop safety device on all electrical saws."

California AB 2218 - "This bill would prohibit a seller, on or after January 1, 2016, from selling a new table saw in this state unless that table saw is equipped with injury mitigation technology, as defined."

Note how AB 2218 tries to piggyback the rationale for SawStop requirements on other much more reasonable safety laws - those regulating the manufacture of products intended for children: "bunk beds, infant cribs, and toys".

[mklotz]

You can turn it off? It's not hot-wired into the saw power? If it's turned off when you start the saw does it sound a siren to warn you that you're not protected from your own inattention?

See where I'm going with this? The more bells and whistles required to make it practical just provide more opportunities for it not to be working when you push your hand through the blade because you were watching football on the shop TV while sawing fence rails. (Don't laugh, a well-educated engineer who lives a few doors down did just that.)

I can completely understand a lawyer wanting to get his product made mandatory. I can hear the whining now...but, it's for the children!

[C-Bag]

It doesn't surprise me that there is more a monetary than true safety angle to it. What are you going to do when it gets a false positive and destroys itself? Or worse yet it bites your finger just enough get it tangled but it's now the device has destroyed itself and won't turn to let your finger go?

I'm with Marv, the best safety device is between your ears. The four carpenter/cabinet makers I know have all had fingers/thumbs cut off and all said it was their fault, not the saw. If I'm not in hyper vigilant mode on any machine I back off. Soon as I'm too comfortable and not wary is when I get hurt.

Engage brain before hitting the switch, period.

It is disheartening though to see another law that seems to be doing more damage than good. Over in Hobby Machinist there's a thread going on that started with a guy ordering I think a rotary table from Grizzly and they cancelled the order because of the change to a law that says you can't sell brass with lead in here. Needless to say that's caused quite a row and a round of CA bashing.

[Toolmaker51]

Sorry fellas. I was between this starting and concluding, so my jab is going to irritate a portion. So, edited in some novelty to lessen the blow.

It doesn't surprise me that there is more a monetary than true safety angle to it...guy ordering I think a rotary table from Grizzly and they cancelled the order because of the change to a law that says you can't sell brass with lead in here. Needless to say that's caused quite a row and a round of CA bashing.

Have instances occurred where customers are ingesting rotary table components? Don't get me started on lawyers.
Well, as an exCA myself, few get more enjoyment than a former loyalist. Moving here, was asked many times...BUT WHY? Response; going to open a suspender store. A percentage found it plausible.
Personally hate the drive to make things physically 'safe'. Electrical safety and such are one thing. The trend in autos; pedestrian detection; lane departure, auto braking, crash avoidance? What are drivers doing more important than piloting a vehicle, besides maxing out their cell data plan, finishing cosmetics...? I can't wait for the first manufacturer liability suit pursued by defense attorney based on one of those being ineffective.
PJs statement tallies it up. "It is impossible to make anything foolproof, because fools are so ingenious."
Yup, they've got all day too.

[PJs]

Oh Boy, Howdy! "It is impossible to make anything foolproof, because fools are so ingenious." anonymous, (theoretically Murphy's 3rd law). Lord knows I spent half of my engineering career developing products with that on the forefront...and only got close.

Personally I prefer common sense and mechanically oriented safety systems. How about a foot switch with a quality braking system engaged when switch is turned off. The idea of a saw that self destructs based on "Relative" conductivity scares me more than the saw. First off I know my skin resistance is less than most people for some reason and second for the obvious stated above and then to disengage it because I'm cutting green wood...I'll be sure and stick with Old Saws, Thank You anyway!

I know Absolutely if I use a push stick and stay a bit offset from the diametral axis and keep all my other body parts way the heck away from a metal blade spinning at ~3k rpm that my body parts should be fine...but no guarantees. Kick back or other distractions are just not allowed in my mind. Still the possibilities exist for a blade to explode or being hit by a comet... Maybe we could buy Insurance for that¿ Support for legalized gambling is a whole other babbling hole...rabbits are banned legislatively.

To be legislated into having to buy (pay the additional legislative cost, tax and hardware/software) once again scares me more than the saw or going into space to wrestle a comet for that matter.

[Paul Jones]

I am with Marv, C-Bag, PJs and Jon on why this is a bad idea. The best way to be safe when using your table saw is to combine common sense with your eyes, ears and nose. Just listening to your saw can avoid at lot of problems and if it seems like your are taking a chance, just don't do it, because there are too many other ways to do the work safely.

[mklotz]

I guess I don't have to ask what the consensus on self-driving cars is, do I?

[C-Bag]

I take it you're not a fan? I know there are a bunch of people locally old and young, who should not be allowed to drive. I guess it just depends on how "smart" the system is. Personally I don't think self driving cars are as stupid as the saw stop. Our new Volt has several safety systems like one that gently steers you back into the lane and warns you when there is something in front of you and you can't stop in time along with proximity warnings , blind spot warning and a rear camera. As long as they continue to function like they do right now I find them useful. But if they turn into bugs in the machine that can't be fixed I'm going to change my opinion, quick.

But I'm often wrong.....