There's lots of safety mechanisms like this in manufacturing. I've also seen "light curtains" which are essentially 2 bars on either side of a hazard. If anything crosses that plane, the machine stops automatically. There are also pressure pads. For one type, you have to be standing on for the machine to operate so that you are in a safe location when it starts. For the other, the pad covers the danger area and the machine will not operate if there's any weight detected. Trying to think of any others I've run into. It's actually pretty interesting stuff. You've got to keep in mind that the operator is liable to be in a hurry, tired, stupid, or any combination thereof.
Another awesome safety system is the SawStop which uses the conductivity of skin to monitor for contact against the blade in a tablesaw. If it detects contact a small explosive charge goes off, instantly sending a block of aluminum into the path of the blade, stopping it dead. Even a serious accident like leaning with an elbow against a moving blade is likely to result in little more than the scratch from hitting a stationary sharp object rather than decapitation.
Sadly the inventor couldn't convince the tablesaw manufacturers to use his invention for cost and/or liability reasons so he had to make his own. Their tablesaws themselves are relatively expensive but cost per accident is $100 for the charge plus whatever the blade costs, so basically $200 to prevent serious injury or death.
Do you know what moisture level sets it off? I didn't even think about that - it's easy to take Southern California's weather for granted. Here it's either pretty much ready from the lumberyard or you got it right off the mill's truck so it has to sit for a few days/weeks.
The lobbying is off putting, yes, but at least his greedy self-interest would do some actual good instead of extracting evermore capital from everyone. Powertools inhabit this uncanny valley of dangerous equipment where they're cheap and accessible enough to the average joe (compared to CNC machining centers or forklifts or whatever) yet powerful enough to do some real damage. My understanding is that the primary reason the major manufacturers didn't want the SawStop wasn't cost but the fear that it would expose them to more liability by making the tools seem less dangerous. I really wish it achieves mass adoption so that the price drops even further.
Thankfully the patents are starting to expire in 2024. Nothing holds pack progress quite like the patent system.
The problem with causing $300 of destruction and lost work time vs possibly saving a limb is there's no fine woodworking operation or framing carpentry operation that requires a table saw. Technically if you feel unsafe working with a table saw you can do absolutely everything very slowly and tediously with a router or router table or bandsaw, or manual tools like a chisel and hammer. Anyone concerned about safety doesn't use a saw stop, they use an entirely different technology than a table saw. If you make a table saw too safe or too expensive to actually use, people will simply use something else. The death toll may or may not be lower...
From a marketing perspective, the people most likely to buy a saw stop because they're scared of table saws will save a lot of money by not buying either sawstop or table saw, and they'll cut dado slots using a hand held router (more dangerous in a different way) or break down plywood using a tracksaw (unholy expensive and many crushed foot injuries) or cut beveled edges on a router table or zillions of alternatives. Meanwhile the people who don't care about safety because they're not drinking on the job or they actually use the substantial amount of safety gear that makes a table saw perfectly safe OR they only do operations on the table saw that are inherently safe by nature (as opposed to relatively low risk operations, and some very high risk operations that people do anyway), will continue to save a lot of money by the combo of not being dumb and not buying sawstop. Finally the real dumb woodworkers who get drunk and get hurt or simply don't care, will continue to not care and not buy sawstop and will not live too much longer in a world either with sawstop or without table saws anyway, so its not like the world will net improve, the Darwin award winners will continue to win Darwin awards. So sawstop is a VERY hard sell.
A similar problem is well manufactured table saws are safer than homemade table saws. The concept of "put a round blade on a motor" is too simple to legislate out of existence. So making table saws illegal wouldn't eliminate table saws it would just mean the homemade ones will make table saws, on average, more dangerous.
Arguably, radial arm saws are more dangerous than table saws and "the marketplace" effectively eliminated those decades ago, so its not like the marketplace dislikes safety or whatever.
> Meanwhile the people who don't care about safety because
> they're [never doing unsafe things]
This sounds an awful lot like suggesting that skilled users of firearms don't care at all about safety because no one's going to deliberately do stupid stuff. It seems farcical to me. Just as with firearm safety rules, they're there to protect people from the rare moments when we are inadvertently NOT careful. History has shown that people DO do stupid stuff because they were thinking about something else, or were tired, or distracted -- hence why every firearm is treated as loaded, even if you unloaded it, and why weapon safeties exist.
For table saws, having a sawstop helps prevent situations that you don't have fill control over from having bad consequences. Of course you'd still use all the same safety measures you normally would without one.
Most firearms accidents happen during normal operations like carrying, cleaning, disassembly, and so on. In comparison table saws are extremely versatile and can do many operations some of which categorically prevent entire classes of accidents. For example I have a commercially made box cutting jig with various shields and guards and its not physically possible to stick my fingers in the blade during operation. If as you claim my mind drifted and I did stupid stuff, by physical design of the operation its impossible to hurt myself.
There's another class of accident involving equipment. Some people do not store firearms with trigger locks or unloaded in safes or whatever. Likewise there's an analogy with table saws where I don't rip small boards without a nice featherboard, riving knife, and some really nice plastic pushsticks. If as you claim my mind drifted, this time by use of tools it would still be physically impossible to hurt myself.
There is a class of inherently dangerous operations where no safety tools exist but the table saw is so versatile and flexible people can successfully do the operation... most of the time. My point is instead of spending more money to build a "better" tablesaw to do something dumb, simply invest the money in a COTS bandsaw or track saw or jigsaw hole cutting jig or chainsaw or planer or whatever crazy risky thing there's a better, faster, safer tool. You can do dangerous things with a table saw but there's always a better safer faster way to do it with a different tool. Taking away money by making the required table saw more expensive just means the woodworker will not be able to afford the superior even safer tool for the job.
Ha! You described me to a 't' and all that makes sense. As a programmer I didn't want to risk my fingers even with a SawStop cabinet so I invested the money in a Festool tracksaw and Domino instead. No crushed foot injuries yet but man I wish I had a tablesaw to cut thin pieces from stock that aren't wide enough to fully support the track.
Or they went about developing their own systems. Bosch made their own system that didn't involve slamming a brake into the blade, but SawStop decided to throw some money around and get an injunction against it.
All the evidence I've found is super cloudy, but early reports indicated Bosch's variant predated SawStop's release.
Luckily SawStop's patents expire in a few years so hopefully we'll see other safety mechanisms similar to SawStop without the downsides and greed.
I have no idea on the moisture levels that cause it to be set off, I just remember reading/watching a video about it because at first it seemed like technology that SHOULD be widely used and implemented. When I first learned about it I thought it was a great idea.
Current saw stop units do have an over-ride switch so that if you know you're going to cut questionable wood, you can disable the safety mechanism for a series of cuts. (The safety mechanism comes back on if you power the table saw off, then back on.) But of course you don't know advance for sure if the piece of wood in hand will trigger the safety mechanism or not.
Not everybody's cup of tea, but our ability to be 'present' is highly variable, both person-to-person, and one person over time. I'm a somewhat daydreamy sort of person, so I work to bring focus when I'm using power tools. As a hobbyist I walk out of my shop when I get tired, emotional, or otherwise distracted, but that's not an option for everyone.
The one at our *kerspace has tripped numerous times on damp wood, laser-cut wood, shiny laminates that didn't register as metallic but apparently it was a full moon that day or something, etc.
It's also saved a few legit fingers, so it's still a net win, but you've got to have pretty deep pockets to cover all the false trips.
It is true, laser cut wood and burnt wood in general also sets it off. However on all saw stop saws I've used you can disable the safety when you have to cut those materials.
One thing I'm still unsure of regarding table saws: is there really much risk of injury if you follow all of the typically recommended safety practices?
Every tablesaw injury I remember hearing about involved the operator failing to follow some of those guidelines.
This goes back to the basic point of safety work: Even the best trained, most attentive and careful operator can get into dangerous situations. There's no way to anticipate the moment that their attention might wander or some external circumstance might just force the situation.
Is there anyway to do it magnetically using inducted currents? I doubt you can stop the saw that way, but you should be able slow the blade down so it does not do as much damage.
A tablesaw goes through a finger as if it is nothing. Fingers can move at speeds of dozens of centimeters per second. So anything that takes longer a dozen microseconds to stop the blade will not be good enough to let you keep your finger.
Another one is machinery where you have to "enter" the machine to do maintenance. Think industrial ovens.
You're supposed to turn off the circuit breaker and lock it with your own personal lock that only you have the key to. That way no one can turn it on even if they wanted to.
I've heard no one, under any circumstances is allowed to take the lock off. If the person leaves after their shift and forgets to take it off for example, they have to come back in the middle of the night so to speak and take it off.
As someone else mentioned, that's a lockout-tagout procedure. Very common when doing any kind of maintenance on a machine. You isolate the power sources and place a personal lock on it to which only you have the key. It usually has your name and an ID number written on it. The lock cannot be removed by anyone else. If you, for instance, forget to take your lock off and go home, it's a very long process where they have to get someone high enough up the chain to get in contact with you and either get you to come back or confirm that you're safely a long way away from the machine before they can cut the lock off. This makes your management very unhappy and most places that I've worked will write you up for leaving while the equipment is still locked out if maintenance is finished and it's safe to operate.
It's not only electricity that needs to be isolated and locked out. A lot of machines use air pressure to operate moving parts, so in that case you'd have to isolate all electrical sources as well as the air. The machines I usually mess with require 2 locks. Some of the machines I've seen can require 6 or more locks to be fully locked out and safe to work on.
When I served on a submarine, tagout procedures were followed to the letter.
A typical maintenance period might require 100 or so separate tagouts, each of which could require anywhere from one to dozens of tags. Each duty watch was required to show up early enough to go through the entire tagout book and at least know the gist of what was in progress.
Finding a loose tag was an automatic all hands all work stoppage, until it was tracked down and resolved. No questions, even if your work was in a different compartment, or had no logical connection to what he tag was for.
Each new tagout request had to be signed off on by at least three people, sometimes all the way up to the captain and not just a foreman or supervisor but one or more shop heads.
Seawater system tagouts on a floating sub were serious business.
Not just equipment you have to enter. This is used in situations with "stored energy" or other systems that need to be turned off or otherwise disabled for safe maintenance. There are multi-lock hasps that can be used if multiple people have overlapping needs to lock out the system, and other devices such as valve handles covers, etc., that help with locking out components don't have a built-in place for a lock.
These make the worst horror stories I've read from various safety organizations. Tanks with gases (nitrogen is particularly sneaky), ovens, radioactive sources... If you want to learn about industrial risks based on real stories watch the CBS videos https://m.youtube.com/watch?v=f2ItJe2Incs
>one type, you have to be standing on for the machine to operate so that you are in a safe location when it starts
Of course, the weakness of a system like this being if middle management is demanding unachievable timelines and/or people in the shop are willing to cut corners, someone can leave a box of heavy stuff on the pressure pad to "save time." Absolutely right that all these systems need to be resilient to operator tiredness etc
