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CT Scans of New vs. Used SawStop

177 points by saltypal 2y ago

WillAdams 2y ago
Does making tools more expensive really benefit anyone other than the companies which own the patents which make them more expensive? Of these 30,000 injuries per year, how many happen when the blade guards are removed? How many happen when a push stick is not used? How many happen when a person stands in the direction that a piece of wood will be thrown by kickback? Once all those are subtracted are there enough injuries to count? What if all tablesaw injury cases were tried by a jury of shop teachers? 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. SawStop goes on about how they will license their patent, but the licensing being offered is a very narrow one and doesn't seem to include the entirety of their patent portfolio, and they have fought very hard to keep tools with similar capabilities out of the U.S. market claiming patent infringement.
- unsnap_biceps 2y ago
  You're not required to purchase them if you don't want to. Personally, I have a stopsaw. It has never triggered, so beyond initial purchase price, it hasn't cost me a cent extra, but in the unlikely case where I do something dumb or have an accident, I feel better knowing it won't be life altering and all I'll need to do is replace a blade and a $99 cartridge. That's worth it to me.
  - abakker 2y ago
    likewise, but also worth noting that the saw stop saw is just a...nice saw. Better than the old delta I used to have, better than the powermatic 66 that I grew up using. Probably not as nice as my buddy's $20k sliding Felder saw, but...for the price, a Sawstop is a nice tool and highly competitive in build quality.
- Blackthorn 2y ago
  To be fair, other companies haven't been trying very hard. I hate Felder for this. They have their own tech to drop the sawblade when they sense fingers. And they use it as a form of market segmentation, only offering it on their $30k+ tablesaws and not on their less expensive ones. > 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.
- mlyle 2y ago
  > Of these 30,000 injuries per year, how many happen when the blade guards are removed? How many happen when a push stick is not used? 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.
  - bigstrat2003 2y ago
    > 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. I think it's reasonable to say "we have done enough" at some point though. We can debate where the point is, but safety is not an unalloyed good. It has a cost, and reasonable people can disagree over whether a particular safety invention has enough ROI to justify its existence. For example, we wouldn't countenance banning all motor vehicles even though we could eliminate all car related deaths with that one simple trick. We would get a fair bit of payoff, but the cost would just be too high to justify it. Similarly, if we could inflict a very minor cost on everyone in the world to prevent one death per year, that would be too low of a payoff even though the cost is very low. So yes, we can always add more layers of defense against accidents (or security incidents). But eventually, the juice isn't worth the squeeze and you stop. So I don't think the Swiss cheese model really can justify any particular intervention by itself; you have to evaluate the specifics of whether the particular intervention is worth it.
    - toast0 2y ago
      > I think it's reasonable to say "we have done enough" at some point though. We can debate where the point is, but safety is not an unalloyed good. It has a cost, and reasonable people can disagree over whether a particular safety invention has enough ROI to justify its existence. That has to be a point in time decision though. Closed circuit TV backup cameras in cars have been possible since I dunno, probably the 70s, certainly 80s technology could have done it; but they weren't a reasonable intervention (outside of say armored cars for currency transports) until more recently as cameras and displays have gotten less expensive and quality has improved. Also helpful as modern vehicle design has resulted in significantly reduced visibility compared to the past, but that's a rant for a car article :P
- bsder 2y ago
  The saw manufacturers all blew off SawStop because they were worried that they would now be liable for any injuries which still occurred. Simply make table saw manufacturers liable for any injury from the saw and this kind of mechanism will instantly become default.
  - Animats 2y ago
    Yes, they did. They even tried to legislate against SawStop. See "H.R. 8181: Preserving Woodworking Traditions and Blocking Government-Mandated Monopolies Act"[1] Didn't go anywhere. There is supposedly woodworker opposition.[2] "Many woodworkers argue that the implementation of SawStop technology has disrupted traditional woodworking practices. Some feel that it has altered the craft in a negative way by making it less reliant on skill and attentiveness, instead placing an emphasis on technology to prevent accidents. This shift in focus is seen as a departure from the fundamental principles and values of woodworking." However, no actual woodworkers are quoted, and the author has a tool store, so this is probably astroturf PR. That web site is addressed to people with a semi-religious attitude towards woodworking, not to working carpenters or cabinetmakers. (Having used circular wood saws, I am all in favor of blade-stop devices.) [1] https://www.govtrack.us/congress/bills/118/hr8181/text https://www.govtrack.us/congress/bills/118/hr8181/text [2] https://www.woodworkcenter.com/why-do-woodworkers-hate-the-inventor-of-sawstop/ https://www.woodworkcenter.com/why-do-woodworkers-hate-the-i...
    - bawolff 2y ago
      > "Many woodworkers argue that the implementation of SawStop technology has disrupted traditional woodworking practices. Some feel that it has altered the craft in a negative way by making it less reliant on skill and attentiveness, instead placing an emphasis on technology to prevent accidents. This shift in focus is seen as a departure from the fundamental principles and values of woodworking." Wow. This is basically: real men enjoy getting their fingers cut off.
      - duskwuff 2y ago
        Ideologically speaking, it's the same sort of people that opposed seat belt laws in the 1980s on the grounds that they'd encourage risky behavior by drivers. (They don't.)
- RajT88 2y ago
  > Does making tools more expensive really benefit anyone other than the companies which own the patents which make them more expensive? 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.
  - PaulDavisThe1st 2y ago
    > I would pay thousands to avoid losing part of my hand. I cut off the distal segment of my right thumb on a table saw in 1995. The initial bill, before I disputed it and received a "professional courtesy discount", was $25k. So, you can pay a relatively small price to avoid losing part of your hand, or you can gamble that it will never happen, and then pay a high price for losing part of your hand. Pretty simple choice to me. ps. Doctor: what do want to do with the rest of your life? Me: well, I'm a programmer right now, but I'd rather be farmer Doctor: I know a lot of farmers with less digits than you still have, and you'll still be able to hit the space bar as-is.
    - atmavatar 2y ago
      In effect, a SawStop system is like a one-time health insurance payment that prevents you from getting injured in the first place, only without jacking up the price because you used the tool in someone else's garage.
    - numbsafari 2y ago
      Good thing you and the doc weren’t on opposite sides of the tabs v spaces discussion. Ed: The fact that you can hit the space bar with either hand, whereas the tab would require changing your keyboard layout is not a consideration I had previously considered in this debate.
      - PaulDavisThe1st 2y ago
        You might say that the doc and I were aligned over the tabs vs spaces discussion. That is: tabs to indent, spaces to align.
- wat10000 2y ago
  Are you suggesting that injuries don’t count if the operator’s actions contributed to them and they’re not worth preventing?
  - WillAdams 2y ago
    I'm suggesting that people should have a sense of personal responsibility when operating potentially dangerous equipment, and that a person should not be required to pay extra for a business or hobby just because some well-to-do patent lawyer has come up with a business model which has an end-game of requiring that patents from his company be required in products.
    - Spooky23 2y ago
      Your way of thinking is why things like safety glass, headrests, and seatbelts were kept of of cars for so long. It’s a fine principled argument, but stay the hell away from product management.
    - lazide 2y ago
      Just wait until you hear about building codes requiring mandatory AFCI and GCFI breakers.
    - wat10000 2y ago
      You can’t control what sense of personal responsibility people will or will not have. So saying that they “should” have it means absolutely fuck all. A requirement for this safety feature would be enacted in order to prevent a large number of accidental mutilations. It might make money for certain people and they might push it for that reason, but that’s not the main purpose for enacting it. I look forward to your complaint that you’re forced to spend money on seat belts you don’t need.
    - danparsonson 2y ago
      > personal responsibility Ah personal responsibility! The magic bullet that mitigates all accidents. All of your personal responsibility will vanish the instant you injure yourself horribly - then you'll be wholly reliant upon numerous other people who will have to deal with the horror of what you've done to yourself, or else be delayed in receiving their own care because of it.
- onlypassingthru 2y ago
  > Does making tools more expensive really benefit anyone other than the companies which own the patents which make them more expensive? 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)
- bagels 2y ago
  Why have airbags in your car? All you have to do is not crash.
- ckozlowski 2y ago
  This is Stumpy Nubs argument (YouTube: https://www.youtube.com/watch?v=nxKkuDduYLk); https://www.youtube.com/watch?v=nxKkuDduYLk); that patience, forethought, and use of a blade guard and other tools would prevent most injuries. I'm in agreement. 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.
andrewflnr 2y ago
Usually those fancy 3D displays are miserable on my phone, but the ones on this page pretty much just work. Lovely surprise.
- zo1 2y ago
  Ironically, previous ones worked beautifully for me but this one fails on my desktop Firefox. Couldn't even select text on the page to copy paste, utter failure.
  - andrewflnr 2y ago
    Just checked. It was indeed a lot worse on my more powerful linux desktop than my android phone. Firefox in both cases. Computers are stupid. :D
chewbacha 2y ago
Wait, so is it a one time function? Can the wire be reset?
- GiorgioG 2y ago
  IIRC you need to replace the brake cartridge and the blade.
- isatty 2y ago
  AFAIK all sawstop catridges are one time use only and also destroys the disk. This is not really a bug.
  - lazide 2y ago
    Yeah, reliably stopping a heavy very fast spinning object in just a few degrees of rotation is necessarily violent.
    - DannyBee 2y ago
      Actually not. My handguard saw will do as well as the sawstop non-destructively (independently tested and verified, so you don't have to take their word for it). They do it (basically) by predicting whether your hand will touch the blade, rather than waiting until it does touch the blade. If you wait until someone actually touches the blade, then yes, you have to operate very very fast. That is unavoidable due to physics, as you say. But if you can gain 100ms or 250ms by proving a 100% probability that the hand will touch the blade before the person can stop it, you now have a lot more time to stop the blade.
      - lazide 2y ago
        How is that going to work reliably with sawdust and the like everywhere? Some kind of radar?
        Snoozus 2y ago
fasthands9 2y ago
Mostly unrelated, but I don't think SawStop is releasing its patent anytime soon like the article states. That SawStop press release was the CEO saying they would do so if the CPSC rule was passed, but the rule wasn't voted on. And even then they were only releasing one of their hundreds of patents.
- voisin 2y ago
  I recall reading that the majority of their patents were expiring in the next few years and the one that they’ve offered to not enforce (rather than release) is the important one that doesn’t expire until the 2030s.
  - dpkirchner 2y ago
    Yup -- Planet Money did a podcast about the sawstop and talked about the patents and controversy: https://www.npr.org/2024/09/20/1200551215/sawstop-steve-gass-patent-cost https://www.npr.org/2024/09/20/1200551215/sawstop-steve-gass...
- fastball 2y ago
  It says that at the end of the article. > 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.
  - fasthands9 2y ago
    My comment is pointing out that the regulations will never go into effect. The scheduled vote on the regulations was postponed this year, and it seems unlikely it would pass once it becomes Republican majority next year.
- DannyBee 2y ago
  They've pretty explicitly been willing to release all of the relevant patents. The truth is it was always a red herring for their competitors. The major players all have systems that don't rely on these patents. 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.
jdprgm 2y ago
Off topic but I wonder how broadly the idea of very expensive failure scenarios but human damage is avoided could be applied to industry at large...
- bluGill 2y ago
  Depends on the system. This would be my second to last choice as an engineer. First choice should always be design the system so you can't get hurt in the first place - but nobody has any ideas on how to do that to a table say (or we have ideas but it no longer can do the job of a table saw and so must reject them). Second is to put guards in places - we have been doing that since at least the 1980s (probably before, but I'm not old enough to remember), but guards are not perfect and so people still can lose a finger even with guards used correctly (cheap guards often limit the functionality of the table saw by enough that everyone just removes them, but even good guards are not perfect). Only after the above would I look at stopping the system when a problem is detected. Last, but only if all of the above fails - is you put warning stickers on. 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]
- mikey_p 2y ago
  An example might be railroads putting a derailer at the bottom of a hill to protect industry or businesses. The derailer is removed when servicing the line, but put back to protect the end of the line industry from run-away cars. Conclusion: they'd rather have run-away cars de-rail and have to recover them, then letting them damage a factory or business.
jchw 2y ago
I would be glad to see better table saw safety mechanisms, though I'm skeptical that 1. This will actually happen 2. That patent is the only one that will wind up mattering. I can't help but wonder if a big part of the reason the number of incidents is so high is because we're intentionally hyperbolic about risks when it comes to warning labels, for liability reasons. As an example, many appliances will warn that you can never operate them with the covers off and doing so can cause death or serious injury. Okay fine, sure, it's not necessarily safe, and perhaps you could indeed kill yourself by accident doing so. However, in practice it's bullshit. People do this all the time, and you pretty much have to sometimes. How the hell are you even supposed to troubleshoot without being able to see what's wrong? Just guess? So sometimes when it comes to warnings it's easy to empathize with the person who didn't take them very seriously, as we're pretty much conditioned to take warnings like this with a grain of salt. Though honestly, when it comes to using a table saw, the thing I'm actually afraid of is kickback. Amputation risk is still very serious of course, but I feel safe enough with the many layers of mitigations I already use. I don't want to fall into complacency, but I also don't think I'm going to lose sleep over not having a SawStop table saw either. (I am not using my table saw often enough for it to be a terrible concern anyways.)
- GuB-42 2y ago
  My grandfather is 90, he was a woodworker, he lost two fingers to a table saw. Few woodworkers of his age have 10 fingers. Workshops are much safer today and woodworkers can expect to end their career with all their fingers. That SawStop thing is one of the many things that can contribute to it. 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.
  - bamboozled 2y ago
    Because as much as we know saw stop works. No one wants to actually find out if works. Disclaimer: cabinet builder.
bawolff 2y ago
What's the story on the patents? If it was invented in 1999, shouldn't they have expired in 2021?
- bluGill 2y ago
  They refined the invention over the years. Some of the additions are very useful and those patents won't expire for a few more years.
thebigman433 2y ago
Not really related to the actual content of the post, but I use a Lumafield at work constantly and love it! The scan quality and software is amazing. Scanning electronics is so much fun, and so helpful!
hettygreen 2y ago
I bought my sawstop shortly after my partner started working in the medical field, where they'd see saw related injuries or amputations come in weekly. Saw was expensive, yeah.. but they hold their value on the second hand market, if you ever even see them for sale. I had a cabinet maker over last week, after he noticed my sawstop he showed me his 2 partially missing fingers. The company also isn't playing games, the saw is beautiful and a lifetime purchase.
- stavros 2y ago
  > they hold their value on the second hand market With the topic under discussion, this is an amazing pun.
  - xattt 2y ago
    No way of getting a five-finger discount on these.
weinzierl 2y ago
Thanks to the author for not burying the lede. This is how an informative article should look like and it was a joy to read.
- beAbU 2y ago
  It's Ironic that this is basically an ad. Lumafield is an industrial CT scan provider, and these articles serve as an advertisement of their capabilities. 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.
orbital-decay 2y ago
Is it feasible to stop the blade in comparable time by reversing the motor?
- MaxikCZ 2y ago
  My guess the stopping will happen in comparable time it takes to start it. So, no?
  - orbital-decay 2y ago
    Much faster if you send the peak current, though.
    - beAbU 2y ago
      The start-up current of large table saws are truly massive. As in multiples of it's nominal "peak" operating current. So to bring the blade to a complete standstill, in significantly less time than start-up, is probably not feasible, unless you have a massive bank of capacitors with stored energy so that you can dump all that current in the motor without burning your building's wiring. But that will probably vaporize the motor.
- raverbashing 2y ago
  No, these motors usually have a very slow spin-up time (probably an induction or a DC brushed motor) 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)
- rocqua 2y ago
  Generally you want to oull the blade down, more than you want to stop it. Get it away from the finger, rather than stop it so a finger can push into it safely.
- grues-dinner 2y ago
  A basic consideration of the energy involved should tell 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!
Freak_NL 2y ago
The question that bothers me whenever SawStop comes up: why does it appears as if this isn't much of a thing outside of the US? Or is it and I'm just not seeing it from my Dutch viewpoint? Does anyone know of anyone who has written about this discrepancy with some numbers (emergency room admissions, SawStop sales) backing it?
- deleted 2y ago
  [deleted]
- moooo99 2y ago
  > why does it appears as if this isn't much of a thing outside of the US? 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.
  - rusteh1 2y ago
    Not true. They are widely available and used in Australia.
  - zitsarethecure 2y ago
    Bosch REAXX has a significant advantage, that being it is non-destructive to the saw blade when it activates. All you have to do is press a reset button and you are back to work. Not having the option of buying this tech instead of SawStop's in the US was a net negative for consumers, IMO.
  - Blackthorn 2y ago
    > Patents. SawStop does not sell outside the US/NA to my knowledge and they hold all the patents required. I think it's more regulatory. There are regulations in the EU around things like blade stop time that products designed for the USA do not meet.
jasode 2y ago
>, I have an altendorf handguard sliding table saw, which will stop as fast as the sawstop, The alternative approaches from other industrial saw manufacturers that are "non-contact non-destructive" are interesting: - cameras and machine learning used by Altendorf "Hand Guard": https://www.altendorfgroup.com/en-us/machines/altendorf-hand-guard/ https://www.altendorfgroup.com/en-us/machines/altendorf-hand... - inductive proximity (same science as Theremin[1]) used by Felder "PCS Preventative Contact System" : https://www.felder-group.com/en-us/pcs https://www.felder-group.com/en-us/pcs - SCM "Blade Off" (not sure of detection method ... looks like inductive proximity) : https://www.scmgroup.com/en_US/scmwood/products/joinery-machines.c884/sliding-table-saws.896/l-invincibile-si-3-blade-off.203887 https://www.scmgroup.com/en_US/scmwood/products/joinery-mach... But I've heard reports from 3rd-parties that Altendorf's camera detection method is unreliable/glitchy and doesn't work as well as Felder's system. Maybe Altendorf fixed the bugs. Also, Altendorf's philosophy of using cameras & ML instead of inductive proximity reminds me of Tesla's philosophy using cameras instead of LIDAR (Waymo). [1] https://en.wikipedia.org/wiki/Theremin https://en.wikipedia.org/wiki/Theremin EDIT ADD: >I'm not sure how comparable these alternatives are when two of them are "request a quote" kind of pricing, and the Altendorf is $7000+ My comment was about "industrial saws" so they're definitely not realistic alternatives to buying a jobsite SawStop for homeowners. I added italics to the adjective "industrial" to clarify this.
- miunau 2y ago
  I'm not sure how comparable these alternatives are when two of them are "request a quote" kind of pricing, and the Altendorf is $7000+, unless you're considering an entire cabinet. None of them will go on a job site with you, for example. I would love to test the Felder system though.
  - Blackthorn 2y ago
    Yeah, they aren't comparable in the least. These companies use it for market segmentation. You'll only get this on the ridiculously expensive table saws. Whereas a Sawstop cabinet saw (the industrial one!), still expensive for an American-style table saw, is a fraction of the price. In the case of Felder, 10% the price!
ejs 2y ago
I love my sawstop, it's a great machine. Often times when a product has some patent-protected feature, the product itself is substandard, but I have not found that case with sawstop. It's one of my highest quality tools. It would be nice if the mechanism wasn't so destructive. I accidentally had an aluminum fence just a fraction of a mm too close, and it touched the blade. I was using a dado stack, and it did a number on the carbide teeth of the blades. Good dado sets are not cheap, nor is the sawstop cartridge.
- thelastparadise 2y ago
  [flagged]
  - manfre 2y ago
    The feature is equivalent to crumple zones on cars. The car destroys itself to lessen the damage to the operator.
- hyperbovine 2y ago
  I'm struggling to imagine a scenario where dadoing <1mm from the fence was a good idea in the first place. I'm assuming you're talking about a miter/crosscut fence but still...
  - icey 2y ago
    Cutting a rabbet? Probably should have used a sacrificial fence, but it's easy to see how this could happen.
  - mikey_p 2y ago
    Could be an aluminum extrusion or something in a miter gauge or cross-cut sled.
  - mturmon 2y ago
    I've stopped myself just in time from triggering my Sawstop while using an aluminum miter gauge. The scenario is that the gauge was set with reasonable (1cm) clearance at one angle, and then I changed the angle without re-checking the clearance, and the back side of the fence swiveled into the blade path. Pythagorean fail. Or, perhaps with GP comment, used a setup with reasonable clearance for a regular blade, and then put in a wider dado, which ate into the clearance.
aidenn0 2y ago
My shop teacher seemed to think the band saw was more dangerous than the table saw. Was he wrong, or is it just that table saws are used so much more than band saws that they dominate the injuries?
- tstrimple 2y ago
  Table saws are dramatically more dangerous than band saws. When a band saw blade makes contact with whatever it's cutting, the force is in a single direction. Down at the table which provides material support. Table saws use a rotating blade and often a fence system. Lots of things can go wrong there, but it typically involves binding between the fence and the blade which can lead to kickback which can send chunks of wood through a wall or potentially more dangerous is it can cause the wood to twist violently into the blade risking bringing your hand towards the blade. 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/wcgw_cutting_a_circle_using_a_table_saw/ 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 https://www.youtube.com/watch?v=JlHe9gOphBw
- oplav 2y ago
  I haven’t used a bandsaw a lot, but I have seen some photos of gnarly lost fingers. 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.
  - tonyarkles 2y ago
    > 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. One of the more horrifying things I've witnessed second-hand with kickback was a lucky third scenario. It was high school woodshop and one morning the teacher pulls us all over to the miter saw bench and points at a huge chunk that's missing from it. The bench surface was two or three layers of MDF glued and screwed together. He explained that someone had been cutting something on the table saw 8 feet away from it, had a kickback, the kickback missed but the piece of wood shot into the miter bench and that was the result. Thinking about what that same piece of wood would have done if it had hit a human... yeesh, I definitely treated kickback with a lot more respect after that day.

177 points by saltypal 2y ago

Does making tools more expensive really benefit anyone other than the companies which own the patents which make them more expensive? Of these 30,000 injuries per year, how many happen when the blade guards are removed? How many happen when a push stick is not used? How many happen when a person stands in the direction that a piece of wood will be thrown by kickback? Once all those are subtracted are there enough injuries to count? What if all tablesaw injury cases were tried by a jury of shop teachers? 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. SawStop goes on about how they will license their patent, but the licensing being offered is a very narrow one and doesn't seem to include the entirety of their patent portfolio, and they have fought very hard to keep tools with similar capabilities out of the U.S. market claiming patent infringement.

unsnap_biceps 2y ago
You're not required to purchase them if you don't want to. Personally, I have a stopsaw. It has never triggered, so beyond initial purchase price, it hasn't cost me a cent extra, but in the unlikely case where I do something dumb or have an accident, I feel better knowing it won't be life altering and all I'll need to do is replace a blade and a $99 cartridge. That's worth it to me.
- abakker 2y ago
  likewise, but also worth noting that the saw stop saw is just a...nice saw. Better than the old delta I used to have, better than the powermatic 66 that I grew up using. Probably not as nice as my buddy's $20k sliding Felder saw, but...for the price, a Sawstop is a nice tool and highly competitive in build quality.
Blackthorn 2y ago
To be fair, other companies haven't been trying very hard. I hate Felder for this. They have their own tech to drop the sawblade when they sense fingers. And they use it as a form of market segmentation, only offering it on their $30k+ tablesaws and not on their less expensive ones. > 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.
mlyle 2y ago
> Of these 30,000 injuries per year, how many happen when the blade guards are removed? How many happen when a push stick is not used? 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.
- bigstrat2003 2y ago
  > 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. I think it's reasonable to say "we have done enough" at some point though. We can debate where the point is, but safety is not an unalloyed good. It has a cost, and reasonable people can disagree over whether a particular safety invention has enough ROI to justify its existence. For example, we wouldn't countenance banning all motor vehicles even though we could eliminate all car related deaths with that one simple trick. We would get a fair bit of payoff, but the cost would just be too high to justify it. Similarly, if we could inflict a very minor cost on everyone in the world to prevent one death per year, that would be too low of a payoff even though the cost is very low. So yes, we can always add more layers of defense against accidents (or security incidents). But eventually, the juice isn't worth the squeeze and you stop. So I don't think the Swiss cheese model really can justify any particular intervention by itself; you have to evaluate the specifics of whether the particular intervention is worth it.
  - toast0 2y ago
    > I think it's reasonable to say "we have done enough" at some point though. We can debate where the point is, but safety is not an unalloyed good. It has a cost, and reasonable people can disagree over whether a particular safety invention has enough ROI to justify its existence. That has to be a point in time decision though. Closed circuit TV backup cameras in cars have been possible since I dunno, probably the 70s, certainly 80s technology could have done it; but they weren't a reasonable intervention (outside of say armored cars for currency transports) until more recently as cameras and displays have gotten less expensive and quality has improved. Also helpful as modern vehicle design has resulted in significantly reduced visibility compared to the past, but that's a rant for a car article :P
bsder 2y ago
The saw manufacturers all blew off SawStop because they were worried that they would now be liable for any injuries which still occurred. Simply make table saw manufacturers liable for any injury from the saw and this kind of mechanism will instantly become default.
- Animats 2y ago
  Yes, they did. They even tried to legislate against SawStop. See "H.R. 8181: Preserving Woodworking Traditions and Blocking Government-Mandated Monopolies Act"[1] Didn't go anywhere. There is supposedly woodworker opposition.[2] "Many woodworkers argue that the implementation of SawStop technology has disrupted traditional woodworking practices. Some feel that it has altered the craft in a negative way by making it less reliant on skill and attentiveness, instead placing an emphasis on technology to prevent accidents. This shift in focus is seen as a departure from the fundamental principles and values of woodworking." However, no actual woodworkers are quoted, and the author has a tool store, so this is probably astroturf PR. That web site is addressed to people with a semi-religious attitude towards woodworking, not to working carpenters or cabinetmakers. (Having used circular wood saws, I am all in favor of blade-stop devices.) [1] https://www.govtrack.us/congress/bills/118/hr8181/text https://www.govtrack.us/congress/bills/118/hr8181/text [2] https://www.woodworkcenter.com/why-do-woodworkers-hate-the-inventor-of-sawstop/ https://www.woodworkcenter.com/why-do-woodworkers-hate-the-i...
  - bawolff 2y ago
    > "Many woodworkers argue that the implementation of SawStop technology has disrupted traditional woodworking practices. Some feel that it has altered the craft in a negative way by making it less reliant on skill and attentiveness, instead placing an emphasis on technology to prevent accidents. This shift in focus is seen as a departure from the fundamental principles and values of woodworking." Wow. This is basically: real men enjoy getting their fingers cut off.
    - duskwuff 2y ago
      Ideologically speaking, it's the same sort of people that opposed seat belt laws in the 1980s on the grounds that they'd encourage risky behavior by drivers. (They don't.)
RajT88 2y ago
> Does making tools more expensive really benefit anyone other than the companies which own the patents which make them more expensive? 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.
- PaulDavisThe1st 2y ago
  > I would pay thousands to avoid losing part of my hand. I cut off the distal segment of my right thumb on a table saw in 1995. The initial bill, before I disputed it and received a "professional courtesy discount", was $25k. So, you can pay a relatively small price to avoid losing part of your hand, or you can gamble that it will never happen, and then pay a high price for losing part of your hand. Pretty simple choice to me. ps. Doctor: what do want to do with the rest of your life? Me: well, I'm a programmer right now, but I'd rather be farmer Doctor: I know a lot of farmers with less digits than you still have, and you'll still be able to hit the space bar as-is.
  - atmavatar 2y ago
    In effect, a SawStop system is like a one-time health insurance payment that prevents you from getting injured in the first place, only without jacking up the price because you used the tool in someone else's garage.
  - numbsafari 2y ago
    Good thing you and the doc weren’t on opposite sides of the tabs v spaces discussion. Ed: The fact that you can hit the space bar with either hand, whereas the tab would require changing your keyboard layout is not a consideration I had previously considered in this debate.
    - PaulDavisThe1st 2y ago
      You might say that the doc and I were aligned over the tabs vs spaces discussion. That is: tabs to indent, spaces to align.
wat10000 2y ago
Are you suggesting that injuries don’t count if the operator’s actions contributed to them and they’re not worth preventing?
- WillAdams 2y ago
  I'm suggesting that people should have a sense of personal responsibility when operating potentially dangerous equipment, and that a person should not be required to pay extra for a business or hobby just because some well-to-do patent lawyer has come up with a business model which has an end-game of requiring that patents from his company be required in products.
  - Spooky23 2y ago
    Your way of thinking is why things like safety glass, headrests, and seatbelts were kept of of cars for so long. It’s a fine principled argument, but stay the hell away from product management.
  - lazide 2y ago
    Just wait until you hear about building codes requiring mandatory AFCI and GCFI breakers.
  - wat10000 2y ago
    You can’t control what sense of personal responsibility people will or will not have. So saying that they “should” have it means absolutely fuck all. A requirement for this safety feature would be enacted in order to prevent a large number of accidental mutilations. It might make money for certain people and they might push it for that reason, but that’s not the main purpose for enacting it. I look forward to your complaint that you’re forced to spend money on seat belts you don’t need.
  - danparsonson 2y ago
    > personal responsibility Ah personal responsibility! The magic bullet that mitigates all accidents. All of your personal responsibility will vanish the instant you injure yourself horribly - then you'll be wholly reliant upon numerous other people who will have to deal with the horror of what you've done to yourself, or else be delayed in receiving their own care because of it.
onlypassingthru 2y ago
> Does making tools more expensive really benefit anyone other than the companies which own the patents which make them more expensive? 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)
bagels 2y ago
Why have airbags in your car? All you have to do is not crash.
ckozlowski 2y ago
This is Stumpy Nubs argument (YouTube: https://www.youtube.com/watch?v=nxKkuDduYLk); https://www.youtube.com/watch?v=nxKkuDduYLk); that patience, forethought, and use of a blade guard and other tools would prevent most injuries. I'm in agreement. 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.

andrewflnr 2y ago

Usually those fancy 3D displays are miserable on my phone, but the ones on this page pretty much just work. Lovely surprise.

zo1 2y ago
Ironically, previous ones worked beautifully for me but this one fails on my desktop Firefox. Couldn't even select text on the page to copy paste, utter failure.
- andrewflnr 2y ago
  Just checked. It was indeed a lot worse on my more powerful linux desktop than my android phone. Firefox in both cases. Computers are stupid. :D

chewbacha 2y ago

Wait, so is it a one time function? Can the wire be reset?

GiorgioG 2y ago
IIRC you need to replace the brake cartridge and the blade.
isatty 2y ago
AFAIK all sawstop catridges are one time use only and also destroys the disk. This is not really a bug.
- lazide 2y ago
  Yeah, reliably stopping a heavy very fast spinning object in just a few degrees of rotation is necessarily violent.
  - DannyBee 2y ago
    Actually not. My handguard saw will do as well as the sawstop non-destructively (independently tested and verified, so you don't have to take their word for it). They do it (basically) by predicting whether your hand will touch the blade, rather than waiting until it does touch the blade. If you wait until someone actually touches the blade, then yes, you have to operate very very fast. That is unavoidable due to physics, as you say. But if you can gain 100ms or 250ms by proving a 100% probability that the hand will touch the blade before the person can stop it, you now have a lot more time to stop the blade.
    - lazide 2y ago
      How is that going to work reliably with sawdust and the like everywhere? Some kind of radar?
      - Snoozus 2y ago

fasthands9 2y ago

Mostly unrelated, but I don't think SawStop is releasing its patent anytime soon like the article states. That SawStop press release was the CEO saying they would do so if the CPSC rule was passed, but the rule wasn't voted on. And even then they were only releasing one of their hundreds of patents.

voisin 2y ago
I recall reading that the majority of their patents were expiring in the next few years and the one that they’ve offered to not enforce (rather than release) is the important one that doesn’t expire until the 2030s.
- dpkirchner 2y ago
  Yup -- Planet Money did a podcast about the sawstop and talked about the patents and controversy: https://www.npr.org/2024/09/20/1200551215/sawstop-steve-gass-patent-cost https://www.npr.org/2024/09/20/1200551215/sawstop-steve-gass...
fastball 2y ago
It says that at the end of the article. > 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.
- fasthands9 2y ago
  My comment is pointing out that the regulations will never go into effect. The scheduled vote on the regulations was postponed this year, and it seems unlikely it would pass once it becomes Republican majority next year.
DannyBee 2y ago
They've pretty explicitly been willing to release all of the relevant patents. The truth is it was always a red herring for their competitors. The major players all have systems that don't rely on these patents. 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.

jdprgm 2y ago

Off topic but I wonder how broadly the idea of very expensive failure scenarios but human damage is avoided could be applied to industry at large...

bluGill 2y ago
Depends on the system. This would be my second to last choice as an engineer. First choice should always be design the system so you can't get hurt in the first place - but nobody has any ideas on how to do that to a table say (or we have ideas but it no longer can do the job of a table saw and so must reject them). Second is to put guards in places - we have been doing that since at least the 1980s (probably before, but I'm not old enough to remember), but guards are not perfect and so people still can lose a finger even with guards used correctly (cheap guards often limit the functionality of the table saw by enough that everyone just removes them, but even good guards are not perfect). Only after the above would I look at stopping the system when a problem is detected. Last, but only if all of the above fails - is you put warning stickers on. 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]
mikey_p 2y ago
An example might be railroads putting a derailer at the bottom of a hill to protect industry or businesses. The derailer is removed when servicing the line, but put back to protect the end of the line industry from run-away cars. Conclusion: they'd rather have run-away cars de-rail and have to recover them, then letting them damage a factory or business.

jchw 2y ago

I would be glad to see better table saw safety mechanisms, though I'm skeptical that 1. This will actually happen 2. That patent is the only one that will wind up mattering. I can't help but wonder if a big part of the reason the number of incidents is so high is because we're intentionally hyperbolic about risks when it comes to warning labels, for liability reasons. As an example, many appliances will warn that you can never operate them with the covers off and doing so can cause death or serious injury. Okay fine, sure, it's not necessarily safe, and perhaps you could indeed kill yourself by accident doing so. However, in practice it's bullshit. People do this all the time, and you pretty much have to sometimes. How the hell are you even supposed to troubleshoot without being able to see what's wrong? Just guess? So sometimes when it comes to warnings it's easy to empathize with the person who didn't take them very seriously, as we're pretty much conditioned to take warnings like this with a grain of salt. Though honestly, when it comes to using a table saw, the thing I'm actually afraid of is kickback. Amputation risk is still very serious of course, but I feel safe enough with the many layers of mitigations I already use. I don't want to fall into complacency, but I also don't think I'm going to lose sleep over not having a SawStop table saw either. (I am not using my table saw often enough for it to be a terrible concern anyways.)

GuB-42 2y ago
My grandfather is 90, he was a woodworker, he lost two fingers to a table saw. Few woodworkers of his age have 10 fingers. Workshops are much safer today and woodworkers can expect to end their career with all their fingers. That SawStop thing is one of the many things that can contribute to it. 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.
- bamboozled 2y ago
  Because as much as we know saw stop works. No one wants to actually find out if works. Disclaimer: cabinet builder.

bawolff 2y ago

What's the story on the patents? If it was invented in 1999, shouldn't they have expired in 2021?

bluGill 2y ago
They refined the invention over the years. Some of the additions are very useful and those patents won't expire for a few more years.

thebigman433 2y ago

Not really related to the actual content of the post, but I use a Lumafield at work constantly and love it! The scan quality and software is amazing. Scanning electronics is so much fun, and so helpful!

hettygreen 2y ago

I bought my sawstop shortly after my partner started working in the medical field, where they'd see saw related injuries or amputations come in weekly. Saw was expensive, yeah.. but they hold their value on the second hand market, if you ever even see them for sale. I had a cabinet maker over last week, after he noticed my sawstop he showed me his 2 partially missing fingers. The company also isn't playing games, the saw is beautiful and a lifetime purchase.

stavros 2y ago
> they hold their value on the second hand market With the topic under discussion, this is an amazing pun.
- xattt 2y ago
  No way of getting a five-finger discount on these.

weinzierl 2y ago

Thanks to the author for not burying the lede. This is how an informative article should look like and it was a joy to read.

beAbU 2y ago
It's Ironic that this is basically an ad. Lumafield is an industrial CT scan provider, and these articles serve as an advertisement of their capabilities. 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.

orbital-decay 2y ago

Is it feasible to stop the blade in comparable time by reversing the motor?

MaxikCZ 2y ago
My guess the stopping will happen in comparable time it takes to start it. So, no?
- orbital-decay 2y ago
  Much faster if you send the peak current, though.
  - beAbU 2y ago
    The start-up current of large table saws are truly massive. As in multiples of it's nominal "peak" operating current. So to bring the blade to a complete standstill, in significantly less time than start-up, is probably not feasible, unless you have a massive bank of capacitors with stored energy so that you can dump all that current in the motor without burning your building's wiring. But that will probably vaporize the motor.
raverbashing 2y ago
No, these motors usually have a very slow spin-up time (probably an induction or a DC brushed motor) 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)
rocqua 2y ago
Generally you want to oull the blade down, more than you want to stop it. Get it away from the finger, rather than stop it so a finger can push into it safely.
grues-dinner 2y ago
A basic consideration of the energy involved should tell 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!

Freak_NL 2y ago

The question that bothers me whenever SawStop comes up: why does it appears as if this isn't much of a thing outside of the US? Or is it and I'm just not seeing it from my Dutch viewpoint? Does anyone know of anyone who has written about this discrepancy with some numbers (emergency room admissions, SawStop sales) backing it?

deleted 2y ago
[deleted]
moooo99 2y ago
> why does it appears as if this isn't much of a thing outside of the US? 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.
- rusteh1 2y ago
  Not true. They are widely available and used in Australia.
- zitsarethecure 2y ago
  Bosch REAXX has a significant advantage, that being it is non-destructive to the saw blade when it activates. All you have to do is press a reset button and you are back to work. Not having the option of buying this tech instead of SawStop's in the US was a net negative for consumers, IMO.
- Blackthorn 2y ago
  > Patents. SawStop does not sell outside the US/NA to my knowledge and they hold all the patents required. I think it's more regulatory. There are regulations in the EU around things like blade stop time that products designed for the USA do not meet.

jasode 2y ago

>, I have an altendorf handguard sliding table saw, which will stop as fast as the sawstop, The alternative approaches from other industrial saw manufacturers that are "non-contact non-destructive" are interesting: - cameras and machine learning used by Altendorf "Hand Guard": https://www.altendorfgroup.com/en-us/machines/altendorf-hand-guard/ https://www.altendorfgroup.com/en-us/machines/altendorf-hand... - inductive proximity (same science as Theremin[1]) used by Felder "PCS Preventative Contact System" : https://www.felder-group.com/en-us/pcs https://www.felder-group.com/en-us/pcs - SCM "Blade Off" (not sure of detection method ... looks like inductive proximity) : https://www.scmgroup.com/en_US/scmwood/products/joinery-machines.c884/sliding-table-saws.896/l-invincibile-si-3-blade-off.203887 https://www.scmgroup.com/en_US/scmwood/products/joinery-mach... But I've heard reports from 3rd-parties that Altendorf's camera detection method is unreliable/glitchy and doesn't work as well as Felder's system. Maybe Altendorf fixed the bugs. Also, Altendorf's philosophy of using cameras & ML instead of inductive proximity reminds me of Tesla's philosophy using cameras instead of LIDAR (Waymo). [1] https://en.wikipedia.org/wiki/Theremin https://en.wikipedia.org/wiki/Theremin EDIT ADD: >I'm not sure how comparable these alternatives are when two of them are "request a quote" kind of pricing, and the Altendorf is $7000+ My comment was about "industrial saws" so they're definitely not realistic alternatives to buying a jobsite SawStop for homeowners. I added italics to the adjective "industrial" to clarify this.

miunau 2y ago
I'm not sure how comparable these alternatives are when two of them are "request a quote" kind of pricing, and the Altendorf is $7000+, unless you're considering an entire cabinet. None of them will go on a job site with you, for example. I would love to test the Felder system though.
- Blackthorn 2y ago
  Yeah, they aren't comparable in the least. These companies use it for market segmentation. You'll only get this on the ridiculously expensive table saws. Whereas a Sawstop cabinet saw (the industrial one!), still expensive for an American-style table saw, is a fraction of the price. In the case of Felder, 10% the price!

ejs 2y ago

I love my sawstop, it's a great machine. Often times when a product has some patent-protected feature, the product itself is substandard, but I have not found that case with sawstop. It's one of my highest quality tools. It would be nice if the mechanism wasn't so destructive. I accidentally had an aluminum fence just a fraction of a mm too close, and it touched the blade. I was using a dado stack, and it did a number on the carbide teeth of the blades. Good dado sets are not cheap, nor is the sawstop cartridge.

thelastparadise 2y ago
[flagged]
- manfre 2y ago
  The feature is equivalent to crumple zones on cars. The car destroys itself to lessen the damage to the operator.
hyperbovine 2y ago
I'm struggling to imagine a scenario where dadoing <1mm from the fence was a good idea in the first place. I'm assuming you're talking about a miter/crosscut fence but still...
- icey 2y ago
  Cutting a rabbet? Probably should have used a sacrificial fence, but it's easy to see how this could happen.
- mikey_p 2y ago
  Could be an aluminum extrusion or something in a miter gauge or cross-cut sled.
- mturmon 2y ago
  I've stopped myself just in time from triggering my Sawstop while using an aluminum miter gauge. The scenario is that the gauge was set with reasonable (1cm) clearance at one angle, and then I changed the angle without re-checking the clearance, and the back side of the fence swiveled into the blade path. Pythagorean fail. Or, perhaps with GP comment, used a setup with reasonable clearance for a regular blade, and then put in a wider dado, which ate into the clearance.

aidenn0 2y ago

My shop teacher seemed to think the band saw was more dangerous than the table saw. Was he wrong, or is it just that table saws are used so much more than band saws that they dominate the injuries?

tstrimple 2y ago
Table saws are dramatically more dangerous than band saws. When a band saw blade makes contact with whatever it's cutting, the force is in a single direction. Down at the table which provides material support. Table saws use a rotating blade and often a fence system. Lots of things can go wrong there, but it typically involves binding between the fence and the blade which can lead to kickback which can send chunks of wood through a wall or potentially more dangerous is it can cause the wood to twist violently into the blade risking bringing your hand towards the blade. 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/wcgw_cutting_a_circle_using_a_table_saw/ 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 https://www.youtube.com/watch?v=JlHe9gOphBw
oplav 2y ago
I haven’t used a bandsaw a lot, but I have seen some photos of gnarly lost fingers. 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.
- tonyarkles 2y ago
  > 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. One of the more horrifying things I've witnessed second-hand with kickback was a lucky third scenario. It was high school woodshop and one morning the teacher pulls us all over to the miter saw bench and points at a huge chunk that's missing from it. The bench surface was two or three layers of MDF glued and screwed together. He explained that someone had been cutting something on the table saw 8 feet away from it, had a kickback, the kickback missed but the piece of wood shot into the miter bench and that was the result. Thinking about what that same piece of wood would have done if it had hit a human... yeesh, I definitely treated kickback with a lot more respect after that day.