The same mechanism is making both things happen at once. Here’s a short explanation:

http://woodworking.about.com/od/recommendations/qt/SawStopBrake.htm

Is there a better way? I don’t know. I’m sure the technology is turning off some potential buyers due to the chance of losing the price of a blade and braking mechanism due to a "false trigger." Hopefully, the success of SawStop in the marketplace will drive others to develop competing systems and we’ll all be better off. As an analogy, I think we would still be using 1995-era computer processors that cost $1,000 each (the processor only, not the computer as a whole) if there wasn’t an AMD to chase Intel and force down prices and improve speed by 1000s of times. In the meantime, SawStop has this market to itself. The product works very well, but its cost is steep right now.

I’d like to point out that, in the demo videos, when the saw blade circuitry senses the contact with, for example, the hot dog, the blade essentially disappears from the frame instantly.

That tells me that there is some mechanism that drops the blade below the surface of the table saw in something less than a few hundred milliseconds.

My conclusion from that, if accurate, is that by the time the blade is driven into the "Saw Stop" anvil, it’s already left the scene of the crime and could not have done ANY further damage to the hot dog or body part.

IF that is a correct assessment, if the blade is below the saw’s deck, I see no reason to stop the blade at all, let alone destroy it and the anvil in the process.

So, my point is, simply, if the sensing circuitry can get the blade that far AWAY from the finger or other intruding object, what justifies the patents for including a self-destruct mechanism, too???

I hope that makes my points a bit clearer, and I’d love to see more information which would support or refute my conclusions. But I have not seen any yet.

Stopping the motor is nice, but irrelevant if the blade has already left the scene.

Maybe Ryobi could use that concept and patent a non-nuclear solution. Otherwise, it’s designed-in replacement parts business, which I personally resent and given a choice, would try to purchase any acceptable alternative for my own use, resources permitting…

Thanks again for your thoughtful comments.

One of the reasons Ryobi lost the lawsuit was because they refused to sign an agreement fully negotiated with SawStop. They pulled out at the last minute and joined a joint effort by the Power Tool Institute to invent an alternate technology. Several years have passed & they have produced nothing.

To stop the blade and force it away from the user quickly enough (a fraction of a second), something needs to mechanically slam into something else. It’s either the blade or arbor. The force of the collision is what pushes the blade away. Stopping the motor won’t be enough if it’s a belt-driven saw (as most are) because the blade/arbor may have enough inertia to make the belt slip and the blade will still continue to turn long enough to cause a severe injury. It would be nice if your idea worked so that a blade and braking system wasn’t ruined, but no one has figured that out yet.

CPSC does have a dog in this fight [oops... can't say that any more either, eh?]… the more regulations they suggest, implement and oversee, the bigger they get and the more money they get and the more power they wield…

Not as if they have any prejucide here, right?
No, I’m NOT a conspiracy theorist… I’ve just been around the sun about 65 times and observed a lot of recurring behavior.

cheers!

http://www.powertoolinstitute.com/pti_pages/safetyvideo_3_TableSawSafety_eng.asp was very interesting and informative, as well as a great reminder to me for how I could have prevented a few cuts I’ve given myself with my own table saw.

And I’ve got some suggestions and “opinions” on the subject, too.

I removed the blade guard from my Delta table saw because it was so difficult to remove it when it had to be removed, as for dado cuts, etc.
The design also made it difficult to see the workpiece and the blade, which I considered a bad tradeoff on overall safety. I tried to remove the plastic guard from the splitter and couldn’t, due to the extra-sturdy attachment method they used, so I removed the whole unit.

I wish they’d made it possible to make the guard easy to remove and replace. Perhaps a suggestion might be for all makers to design guards that
CAN be easily removed AND replaced, preferably without the need for a wrench or other tools… a knob and a slotted hole on the splitter and a few other small design changes could create a positive locating effect for the guard AND allow for easy remove/replace.

My really big gripe is one that nobody seems to have the nerve to touch: the SawStop design, patents, etc.

SawStop is a wonderful feature, and the demonstration videos are incredibly impressive. But as an engineer, one “little thing” really bugs me…

The SawStop sensors and actuators pull the blade away from the invading body part so quickly that it barely nicks the skin of the operator OR the hot dog. Very impressive! And in the videos, without super-slow-motion photography, the blade seems to instantly disappear below the table deck.

Here’s my gripe: why isn’t the “instant-sensing-and-retraction” ENOUGH for the safety folks, users and the Save the Hot Dog Consortia? Why the [heck] does the blade have to be slammed into a stop block, requiring purchase and replacement of the stop block and most likely, the saw blade, too?!

Pardon my cynical attitude, if that’s what it is, but it really seems that SawStop isn’t satisfied with being paid for the invention; they want to deliberately create a replacement/consumables market for themselves, too!

Has anyone asked why they could not have used electronic braking to quickly stop the motor and blade? I used to own an electric lawnmower which could do that… just by turning the power switch from On to Off stopped the blade in a second or two. Once the blade is pulled away from the invading finger or other body part, one MIGHT assume that the danger has been removed to a safe distance. Why the self-destruct “feature” too???

It would also seem that the sensor and retraction mechanisms could be more easily adaptable across the whole marketplace AND, combined with electronic braking [that was 10-15 years ago for my lawnmower] could work in unison with the sensors.

I appreciate PopWoodworking making the link available, and it was a benefit and reminder to me, as well as having taught me a few things I’d never been told before [fancy that!], but I also had no sympathy for the jury or the recipient of the $1.5M award in Massachusetts, either. If I were on that jury, it would have ended up a hung jury or a LOT smaller reward… compensation for medical expenses and maybe a fine for stupidity on the parts of the saw’s operator AND his employer.

Ah, that felt better. Thanks, again!

By the way, yes, I’ve had my table saw, band saw and bench grinder draw blood on me. But I’m a devout freedom-lover, and my bottom line is: I prefer to choose the quality, safety features and whatever else I can when I’m making a purchase. If UL and the CPSC or whoever want to provide me gobs of information to help me make my decision… wonderful.

But if this is the camel’s nose poking under the edge of the tent, the future will bring mandatory qualification, testing and certification before anyone in the future can buy a table saw, lathe, band saw, drill or drill press and on and on and on! One more step in trying to make our lives 100% risk-free, with government regulations making sure we’re safe.

And no one even mentioned the tool I use a lot for creating wood for my lathe to eat… my wonderful Husqvarna chain saw. If they come to make me get a license for that, too, they’d better be well-armed… oops… can’t say that any more, can we?

Years ago, I worked with a guy who thought pushsticks were for sissies. According to him, if you’re careful you don’t need them. He still had all his fingers, and who knows, maybe he still does. But I think we can agree that refusing to use a pushstick is the opposite of being careful.

In the same way, refusing to use a device like SawStop just because you don’t like someone else telling you what’s good for you is the opposite of personal responsibility.

But if the issue is whether a tablesaw without SawStop technology if the operator is aware of his responsibility is just as safe compared to a SawStop tablesaw, that is just flat out wrong. This approach to safety would never fly in any field where safety is a priority. Think of airline pilots, nuclear power plants, operating rooms, or, to take an example from my day job, physicians ordering chemotherapy — they all have redundant safety mechanisms to catch all the errors that might happen, despite the fact that pilots, plant operators, surgeons, and pediatric oncologists are vigilant all day long. These environments are very much like the environment where a woodworker is using a tablesaw. Accidents are very infrequent, but when they happen, the results can be catastrophic.

The model of safe practices that we use is called the "Swiss Cheese" model. The concept is that there are one or more safety measures in place to prevent an accident from happening. For a tablesaw there’s the splitter, blade guard, proper alignment of the fence, and, yes, "responsibility". But what is inherent in each one of these safety measures is that there are holes in each one of them. The splitter might be not thick enough for the circumstance, the blade guard might be removed, the fence might slip out of alignment, and the woodworker becomes distracted for just a second. Many times the holes in one layer will be blocked by one of the other layers. But if the holes all line up, an accident occurs.

In none of the fields I mentioned above do we solely rely on "individual responsibility" to provide the desired margin of safety, simply because it doesn’t work. There are holes in that layer of cheese, regardless of how vigilant we all are. That’s why there are backup plans. The SawStop mechanism provides your plan B if for some reason, a slip occurs despite the fact that you were being as responsible as you could. Those slips can and will happen, and the damage can be very great if and when it does.

So if you don’t want to have a SawStop in your shop because of your feelings of government intervention, that’s fine. But one cannot say that "responsibility" alone will provide the same safety margin that a SawStop provides. Otherwise, pilots and plant operators would not have their checklists, surgeons would not do an instrument count after an operations, and no one would bother to recheck my chemotherapy orders for my patients.

They’ll probably outlaw selling used saws too.

Rich

These things can’t make the saw 100% safe, but what if they prevented 50% of the amputations? (Just to throw a number out there for argument). Wouldn’t that be worth it? (Not to mention eliminating most kickback accidents).

I believe that this overwelmingly popular attitude that accidents are 100% the victim’s fault directly led to the fact that standard safety measures on most tablesaws just suck, and it’s always been that way. Manufacturers correctly reasoned that they were unlikely to be held liable for any accident that occurred. Saw users discounted the value of safety equipment and didn’t demand saws with guards, etc. that worked properly.

The tragedy is that untold numbers of accidents could have been prevented by basic safety equipment that maybe would have added a few bucks to the price of each saw.