If you ask around a wood shop, most people will agree that the table saw is the most dangerous tool around. There’s ample evidence that this is true. In 2015, over 30,000 ER visits happened because of table saws. However, it isn’t clear how many of those are from blade contact and how many are from other problems like kickback.
We’ve seen a hand contact a blade in a high school shop class, and the results are not pretty. We’ve heard of some people getting off lucky with stitches, reconstructive surgery, and lifelong pain. They are the lucky ones. Many people lose fingers, hands, or have permanent disfiguration and loss of function. Surgeons say that the speed and vigor of the blade means that some of the tissue around the cut vanishes, making reconstruction very difficult.
Modern Tech
These days, there are systems that can help prevent or mitigate these kinds of accidents. The most common in the United States is the patented SawStop system, which is proprietary — that is, to get it, you have to buy a saw from SawStop.
The system assumes the blade is all metal. It can detect your hand making contact with the blade, and if that happens, the saw reacts within 5 milliseconds. The system releases a beefy spring that jams an aluminum block into the saw blade, halting the 4,000 RPM rotation almost instantly. The force also moves the blade under the table. The cartridge that stops the blade and the blade won’t survive the encounter, but your finger will.
Tear It Down!
Of course, being Hackaday, we want to see what’s inside the cartridge, and [Spag the Maker] was happy to oblige. As he points out, the sensor sometimes fires when it shouldn’t, but that’s better than not firing when it should.
In this case, the cartridge fired after contact with a metal tape measure. We’ve heard wet wood can also cause false positives. You can see the inside of the dead cartridge in the video below.
Patents
SawStop owns several patents that prevented other similar systems from entering the market. Although many of the patents are now expired, there is one — known as the 840 patent — that is very broad and won’t expire until 2033. However, the current owners of the patent — TTS Tooltechnic — have claimed that if government regulation mandates table saws to have protection devices, they will release the patent to the public.
However, until that happens, the company continues to defend its patents vigorously. The most famous case was against Bosch, who has a competing system called Reaxx. The systems are superficially similar, but Reaxx does not destroy the blade, which only moves out of the way.
Even this year, SawStop litigated against Felder KG, another competitor. There have been accusations that SawStop won’t reasonably license their technology, either, but we don’t know the whole story. Anyway, they’re no Volvo.
Safety First
If you don’t think a woodshop is that dangerous, have a look at “It Didn’t Have to Happen” from many years ago. This isn’t a new problem.
The Consumer Product Safety Commission has tried to force protection systems on table saws for many years. The industry, in general, opposes them as unnecessary and expensive. The controversy is heated, with proponents pointing to the 30,000 plus injuries a year and the cost to the injured and society. The opponents talk about free markets and government interference in your shop. We won’t take sides, but having seen an injury of this type, we’ll spend our money on a safer saw even if no one is making us do it.
Then again, no one is stopping you from making your own saw with whatever safety systems you like. We’ve seen many builds based around a circular saw.
My local makerspace is shared with the local middle school. Their table saw has a saw stop, and we’ve had some trouble with it – the stop triggered for unknown reasons, I think that happened twice, and then the saw was offline until we could get a makerspace member in to replace it.
And the blade, and some table saw blades can be expensive.
I think the right way to do this is to mandate them in schools, then the next generation will grow up having used them, and can make an informed choice.
Cutting an acrylic mirror will trip a SawStop too.
Now, a SawStop cartridge alone costs more than my whole saw did, new (30 years ago…).
“Surgeons say that the speed and vigor of the blade means that some of the tissue around the cut vanishes”
Huh? You don’t need to be a “surgeon” to know this as it’s a commonly known fact.
It’s a blade with a kerf – no one needs to “say” anything – it removes materials to make the cut. That’s why you need to know which side of your line to cut on.
some of the tissue around the cut vanishes
Technically it doesn’t vanish… My dad once had the bright idea to make steaks from the too-big chunks of frozen cow in our freezer, using a radial arm saw (almost as crazy as a table saw). The sawdust was pretty awful stuff. Never tried that again.
Mmmm beef dust
Bosch had a very much improved version several years ago. It did not damage the saw, and replacement parts after the thing triggered were very small and affordable, but they got sued out of the market by sawstop.
And I’ve read a few too many stories about false triggers. From a forgotten nail to simply damp wood, or no clear cause at all. I do like the extra safety, but the high cost of replacement parts after each trigger is no fun. It probably results in disabling the system quite often.
Yeah sawstop seems like a very crummy exploitative company who should have their patents seized and put into public domain
If all safety devices were forced into public domain there would be little incentive to work on safety devices.
I didn’t say all safety devices though did I? They had a good run, plenty of incentive has been generated.
Secondary: the world is currently clogged with extraneous safety devices
Patents for 10 years and an extension for another 10 years were thought up in some other era.
Limiting patents to 5 years should be enough to give companies a “headstart” in this fast changing word. That is what patents were were designed for. Far too oftne it’s used for completely misplaced things. From patent trolls, to making stuff so ridiculously expensive that it limits adoption.
Another thing completely boners is the patenting of trivial things. Many inventions get invented when the time is ripe for them. For example, in the first few years after the invention of the BJT, there was a whole slew of “inventions” of how you can connect these things together.
Torx only saw wide spread adaption after the patents expired. For the vast majority of applications it was not “important enough” to pay the royalties. There is also a weird story around “Robertson” (Those square bits used only in Canada).
A “use it or loose it” policy for patents is probably also a good idea.
Sawstop was “invented” by a group of three lawyers, not “engineers” or “inventors”.
I have no problem with SawStop defending their patents, vigorously even. I DO have a problem with judges and juries that aren’t able to see that the defendant’s product is obviously different or that the patent is obviously too broad. I also have problem with a company using patent litigation to drive a small competitor that can’t afford to defend themselves out of the market, but Bosch has plenty of resources.
You would think if the simply copied the original device they would not have a leg to stand on, as the original design would not be covered under subsequent patents.
“if they”
edit ability please!
Speaking of table saws – this is the funniest clip i’ve seen in my whole life !
Epic !!!
https://www.youtube.com/watch?v=IRq-JUCoHo8
Ok, that was weird….
James Hamilton has a thoughtful discussion of some of the legal and technical issues. No surprise, it’s more complicated than you might think.
https://www.youtube.com/watch?v=nxKkuDduYLk
In case WP eats the link, search for “Sawstop” on the Stumpy Nubs YouTube channel.
Life is inherently dangerous in many different and often unpredictable ways. Devices like the SawStop are more likely to lead people to be careless and inattentive when they encounter dangers because they assume they are “protected” and don’t even consider the hazards.
Learning safe work habits is far more valuable than expensive “safety features”.
The table saw is very dangerous. I don’t use a guard, but I never move my hands near the blade until it is completely stopped. Nor do I reach over the blade when it is spinning.
First question, “Is what I’m about to do dangerous? What is the nature of the risk and how do I mitigate it?” If you can’t instantly answer those questions, you should stop work until you can.
FWIW In 1973 I walked 12” I beams on the I-40 “De Soto” bridge at Memphis for $2.57/hr. No safety gear at all. There were 4 of us who moved the scaffolds and netting for the safety of the rest of the crew. You never look past your feet when moving. Despite that experience, I never stand close to the edge of a cliff. I lie down and crawl to the edge to look down where there are no railings.
Safety mechanisms often exist to protect people who don’t have the mental capacity to model hypotheticals like “Is what I’m about to do dangerous? What is the nature of the risk and how do I mitigate it?”
Way more people than you’d be comfortable with literally can’t do that, they don’t have the hardware… Whether or not it’s a good idea to keep them out of Darwin traps is a different question entirely that probably wouldn’t be allowed to play out
I am in a woodworking school and we are taught very strictly in safety. Yet I see classmates holding workpieces in an unsafe way at the router table. When I pointed out what he did he replied “I will remove my hand before I’m there” then the next pass I see him put his hand very close to the bit. Some people indeed don’t see it.
On the other hand, I just almost broke my arm … by falling down the stairs.
Guards and such are valuable to help hapless individuals who end up working in places where such things are left in place but the rest of the safety culture is summed up with a shrug.
“Nor do I reach over the blade when it is spinning:”
Nor do I. Anymore.
I had a cheap Harbor Freight tools table saw a number of years ago. I also was running it without a guard. I went to reach over the blade, and my right thumb was nicked… it made the most horrid sound and quite frankly was expecting it to fly over my shoulder.
I learned two lessons that day.
– The make sure the blade is stopped thing you mentioned
– And to use the damn guard whenever possible.
TTS/SawStop released its patent to the public last February – is this the same one?
https://www.cpsc.gov/About-CPSC/Commissioner/Richard-Trumka/Statement/SawStop-Dedicates-Its-Patent-for-Public-Use-Boosting-CPSC-Rule-to-End-Table-Saw-Amputations
He apparently misunderstood. They didn’t release any patents. They claimed that they would release a single patent (#9,724,840) if the law passed. All talk, no actions.
I personally like the saw stop. I’ve never heard of one triggering “randomly”, only when someone made a mistake like cutting styrofoam insulation with an aluminum backing. Furthermore I distinctly remember going to church as a kid and noticing how several of the older men were missing fingers. The fact is that the table saw is probably the most dangerous tool in the woodshop. The sawstop makes it safer, for the price of only a minor inconvenience. I would never support legally mandating it, but I will certainly buy one myself if I buy my own table saw some day (and I can afford it).
My parents had a carpenter make a table for them, he missed 2 fingers. We asked what happened. He had played with fireworks as a kid, then decided now he was safe to become a carpenter as he can’t cut those two fingers off!
The larger Sawstop saws are very nice and a great option for those that have both the extra money (3x the price of a decent name brand saw) and want the added safety features. If the law passes and somehow the patent is actually released (and not heavily licensed) 2 things are going to happen:
People are going to make a killing restoring old saws and selling them.
The #1 search term involving Sawstop will start with “how to disable”
Regarding “no one is stopping you from making your own saw with whatever safety systems you like”… This is an absolutely terrible suggestion. Sorry for being a pessimist, but when it comes to safety systems, an extensively tested, commercial product is dramatically more reliable than, generously, the worst 25% of DIY projects. Sure, go ahead and build yourself a table-saw, but don’t rely on it to save your fingers. Meanwhile, lobby your congressional representative for saw safety legislation. Or start a volunteer tool training organization!