CT Scans of New vs. Used SawStop (opens in new tab)

Kind of seems like the opposite. I could be wrong, but in the case of the saw the cameras/AI are probably more expensive to develop and deploy than the inductive sensing. With the cars though, it's the cheaper option for sure.

The whole "releasing our patent" is simply SawStop's way of trying to lock out the competition. All their competitors (including Bosch) have said that it will take several years before they could develop an alternative product leaving them in violation.

Finally, the regulation SawStop is trying to force doesn't even solve the injury problems for a few reasons.

The biggest is that CPSC does NOT affect commercial saws. As it turns out, hobbyists don't have as many injuries as you might think because they don't use their saws all the time and they have a very healthy respect for them (there are exceptions of course). Most serious injuries happen because the guy at the commercial shop has become too complacent and made a mistake after a long day at work. This ruling does nothing to change that situation.

You also can't fix stupid. If blade guards and riving knives are left on saws, the chances of injury are incredibly low, but people choose to remove one or both of these. They'll also turn off the safety features and do something they shouldn't. SawStop safety is over-represented because the people who spend the extra money for one are already predisposed to take safety seriously.

This leads to the price issue. Table saw prices will go up from $220 up to a minimum of $600 or more. This increases the risk of someone not having that much money and then turning their circular saw upside down making an incredibly dangerous table saw without a blade guard, riving knife, or even a parallel fence massively increasing the baseline risk for injury.

I love the idea of SawStop and I think it's an amazing safety device, but after reading the arguments on all sides, I think we should leave the current saws situation alone and instead simply require each saw manufacturer to offer at least one AIM model in their product lineup by 2032 or so (while maybe getting the courts to fix up the colossal screwups they made with the SawStop patents). This will give them time to develop alternatives and maybe drive down prices over time until it finally (hopefully) makes economic sense to only sell AIM devices.

Lawsuit discovery showed all of them had developed their own technology that was fine, patent wise. But it would have eaten into their profit.

Personally, I have an altendorf handguard sliding table saw, which will stop as fast as the sawstop, but not destroy the blade.

> Despite previous litigation against would-be imitators of their safety brake, SawStop has committed to dedicating its original patent to the public when these new regulations go into effect.

American hobby woodworkers all have huge two- or three-car garages giving them the room needed to store and use gigantic machines like table saws. Such large homes are unusual in Europe, and mostly owned by people who don't work with their hands.

European hobby woodworkers don't lose their fingers to table saws because they're using circular saws instead.

I suspect America also has a lot more woodworkers; many of their buildings have wood frames, wood siding, and bitumen-over-wood roofs.

Woodworking YouTube has changed this a bit. Since American creators are so widespread, everyone has gotten exposed to SawStop and I know at least a couple years back people were trying to import American-style table saws instead of the local European-style because that's what YTers have. I don't know if it was regulatory or what that has prevented the former from being more available in Europe.

Patents. SawStop does not sell outside the US/NA to my knowledge and they hold all the patents required.

In 2015 Bosch introduced a system that did essentially the same thing as SawStop, but with a slightly different mechanism. SawStop sued in the US and won against Bosch.

Since 2017 SawStop is part of Festool, which explains why their tech is slowly making their way into Festool products. For example, the TKS 80 has the SawStop functionality built in. But at an MSRP of ~2.500€ it’s not really a hobbyist machine.

If you run commercial production, then you do need a table saw (but one with a sliding table!), but for hobby work you might as well spend some time for track saw setups and be much safer.

I think this is marketing done right. I am not in the CT scan industry, nor do I think I'll ever have the need for these services, yet I came out slightly more knowledgeable about the world around me after reading their article. Maybe one day I will have the need for commercial CT services, and Lumafield will be the first one to come to mind.

With the topic under discussion, this is an amazing pun.

Here's a saw stop in action, so it's not gory. But look at how FAST things go wrong here and how violent the interaction was.

https://www.reddit.com/r/Whatcouldgowrong/comments/11s53ew/w...

Compare that to a band saw in use, and you can see fingers quite close to the to the cutting edge and still have good control over the work.

https://www.youtube.com/watch?v=JlHe9gOphBw

I use a table saw quite a bit and think there are more ways things can go wrong, most of which stem from kickback which happens in a split second. The wood will either fly back and hit you, or your hand will be pulled into the blade and you will likely lose a finger.

Both machines can be safe with the proper precautions. That said, I still enjoy my SawStop as insurance for my fingers since I still write software for my day job.

I'd say overall a tablesaw is more dangerous compared to a band saw because it has the additional failure mode of kickback which happens occasionally even to very experienced operators.

https://www.youtube.com/watch?v=yuWNEAlC2-0

Not something a band saw will do. So a band saw will just cut you while the table saw will cut you but also hurl material at you.

355mm radius disc, mass 1kg, moment of inertia is 1/2 mr², so 0.06 kg.m² [1]. This ignores all inertia of the arbor and motor rotor, mind, which is possibly significant (smaller radius but dense, depends on the transmission whether the motor is part of the blade system - if there's a clutch or belt to let go, then the motor isn't really part of the problem, but it's also not going to be part of the solution), Say it spins at 4000rpm, or 420 rad/s (some saws go to 6000 plus and this is quadratic).

So kinetic energy in the blade alone is 1/2Iw², or 0.5 * 0.06 * 420², or 5.2kJ. For comparison, a rifle bullet is about half that, which seems right ballpark on the face of it.

So to remove that energy in 5ms (SawStop's claim) is 1MW, or a current of 4000A at 240V, or 8000A at 120V. I don't know if any big saws run on that voltage in the US (may small ones?), but let's take the lower rest-of-world figure anyway. That's roughly 1300HP or 4 top-spec Tesla Model Y's at full throttle (320kW each).

This is not completely technically impossible to deliver - you need about 400 0.1 farad capacitors charged to 250V, which are 100mm in diameter and 250mm tall and around $150 each, so a fridge-sized box, maybe two[2]. Some very large and pricy solid state switches will be needed too, and some nice copper busbars to get the current where you need it. Actually pushing 4000A into a motor winding for 5ms isn't that easy either as it's a canonical example of an inductive load, so you need even more current, plus hopefully a way to stop the current when done before turning the inside of the motor into a plasma ball. Evaporating the motor winding before you've stopped the blade is no good, and it'll be nice to use the saw again, so you'll need to uprate the coils massively, which will make the motor very heavy, very large and very expensive.

There are probably other issues like induced voltages far higher than main voltage the will need management. As mentioned earlier, you will also not be able to use, say, a belt drive - the motor needs a very stiff physical connection to the blade.

So, you won't break physics to do this, but it will be large, heavy and incredibly expensive. $50k in caps alone.

Flipping the blade physically away from the obstacle is a much better bet. Which is actually SawStop's real trick - all that kinetic energy in the spinning blade system is grabbed and harvested to move those kilos of steel down and away in a few milliseconds. Stopping the blade is just a handy side effect of stealing all the energy. You could possibly do the same with an electrical system, but it would still be very large and very heavy compared to using the exact same huge kinetic battery that will always be there (or it's not a table saw) and which is actually the threat to safety in the first place.

It's actually quite interesting to see the relative weakness of electrical forces illustrated this way. Even quite prosaic mechanical objects can develop powers that require electrical systems the sizes of small rooms to rival. And again, chemical systems contain more power still: all that spinning mass is the energy contained in a few grams of gunpowder.

[1] Edit: I double counted a factor of 1/2 in the MoI - it's actually more then I first estimated!

[2] Another underestimate as you really need a lot more as you have to get that energy out fast and you can't wait for the slow tail of the discharge curve to finish. Plus at least Nichicon only seem to go to 160V for 0.1uF!

So even if you send peak current it won't (this is for the DC brushed, for the induction it can't be reversed unless you have a speed controller - also called an inverter)

One of them did require a resharpen though.

Let me emphasize: you should run the above list in order. If you can design a problem out then you are not allowed to put guards, brakes, or warning stickers on./

Most industrial machinery is designed with the above process. there is a lot of machinery from early days still around with out safety, but most industry has been adding guards and brakes to those were possible and replacing (machines from the 1950s are probably worn out anyway) the old stuff. Industry also has extensive safety training for the dangers they they cannot prevent other ways. The safety results for industry is much better than it was 100 years ago. Not perfect by any means, but much better and getting better [I was going to write every year, but random chance means some years there are more accidents than others despite the safety situation overall improving yearly]

The idea that safety features cause complacency has been debunked several times. Statistically, well designed safety features or equipment reduce accidents, even if it may cause some people to get complacent.

And you are right to be afraid of kickback, and one of the risks associated with kickbacks is inadvertently touching the blade, that is the issue SawStop is designed to address. The blade guard helps too, but AFAIK, there are many instances where you can't use it.

I've work in multiple production furniture shops and that has not been my experience. People are just moving fast, trying to get stuff done and things happen. Also, training safety in a non-educational setting is tough.

Chainsaws have about the same number of annual ER visits as table saws. It's common to see someone using a chainsaw without most of the recommended safety gear. In those cases, it's probably money.

I would pay thousands to avoid losing part of my hand. The increased price is a very good value, tens of dollars.

Look at rearview cameras. Cheap tech. Used to be a 1000+ USD option. Now that they are government mandated the manufacturers figured out how to include them for a couple hundred dollars.

Price goes up, but just a little. Money well spent.

> The best advice I got in shop class was to slowly and quietly count to 10 on my fingers before throwing a power switch and in doing so to envision the operation from beginning to end and all the forces which would be involved, and to remind myself, that I wanted to be able to repeat that cut when the power was turned off.

It's great advice, but injuries tend to happen when people become complacent with the operations.

But I don't think that companies are trying to make the tools more expensive. In fact, it was the opposite. SawStop sold high-end saws, other manufacturers did not want to adopt the technology because of the cost it added.

The issue of proper saw safety and use of sawstop technology are two different issues, I believe. And while I agree, the proper safety procedures you cite should be used by everyone, they aren't. In fact, they often aren't. And we can sit here and shake our fingers, but it won't change the overall culture around them. And I think that's the conclusion that regulators have come to as well: They're not going to get people to always use their blade guards or count to 10, so they'll mandate adoption of a technology that mitigates the risk due to people not following directions.

Regarding the licensing, I think that's been addressed by others elsewhere. But in short, SawStop defended their patents in order to license the tech. When the government moved to mandate it, SawStop said they wouldn't enforce their patent, but they're not handing the tech over either. Other companies are free to develop their own method without running afoul of SawStop's patents, or they can license SawStop's tech. To me, it seems like a fair approach that both protects their investment while not putting themselves in a morally questionable position in taking advantage of the upcoming regulation.

When it comes to table saws, you only have to make a mistake once to find out. Almost perfect doesn't cut it. (ba dum bum, tss)

Seems like you don't buy into the swiss cheese model of accidents. Because other safety mechanisms and good practices exist, it doesn't mean that there's not reasons to add additional safety. In aviation, we always blamed the pilots for a long time, and it wasn't entirely wrong. However, no matter how much we told pilots "stop crashing and dying!!" they didn't seem to want to stop.

This is there for the day when other things go wrong-- when a tired operator reaches for something he obviously shouldn't; when a blade guard is out of place and someone slips; when someone who isn't sufficiently trained doesn't realize he shouldn't use the table saw.

Simply make table saw manufacturers liable for any injury from the saw and this kind of mechanism will instantly become default.