Are Safer Power Tools In The Future?
Added 2024-04-09 18:25:51 +0000 UTCPending legislation might change the landscape of power tools in the near future. Is it time we moved shop tools into the 21st century?
Comments
A significant part of the cost of each SawStop system is not the detection (which is actually really cheap), but the mechanism to arrest the blade before it does any significant damage (about 5 milliseconds). This is accomplished by deploying a block of aluminum into the blade; part of the inertial of the spinning blade is then used to also retract the blade below the table. Note that the braking cartridge is a one-time-use device, and often the blade is damaged beyond economical repair also. The sensing is done by measuring the capacitance of the isolated blade relative to ground (the cast-iron table, and everything else in the metal body of the saw). When a large, wet bag of meat (the user) contacts the blade, the capacitance suddenly goes way up, whether or not the user is in contact with ground. It's this rapid change in capacitance that triggers the system, rather than requiring any path to ground. The circuitry to do this is really simple, and can be made quite reliable against false triggering with quite simple software filtering. A camera, although also pretty cheap now days, is still a lot more costly than a simple analog circuit, and the processing requirements are much greater too.
Mark Moulding
2024-04-12 22:02:45 +0000 UTCI believe that meat saws (basically band saws used in a butcher shop) have the kind of optical safety technology Fran is describing. The operator wears blue gloves and if anything blue comes near the blade it stops. As a second line of defense, if anything grounded touches the blade it stops (this would happen only if the glove gets breached and the operator's hand touches the saw blade).
Ike Armela
2024-04-12 16:46:00 +0000 UTCThat AI system should probably also be made to detect things like rings, bracelets and hair getting too close.
Maarten Daalder
2024-04-11 14:07:07 +0000 UTCBosch also produces a similar system, but were sued by SawStop and no longer sell it in the United States as a result. Even if SawStop does release public license to all necessary patents, the cost to implement technology on a table saw would drastically change the availability of this tool. SawStop table saws are among the most expensive you can buy. This is partially because they are unarguably a very high quality tool, but it's also because of the cost of the blade stopping technology. It's estimated that, even given the economies of scale which would result from wide-spread adoption, the technology would add $100 to $150 to the *cost* of each saw made; this number would be doubled or even tripled by the time the saw arrived at retail sale. This would completely wipe out the market for $300-$500 consumer-grade table saws, and would also hamstring specialty manufacturers like ShopSmith. Table saws have two major dangers, of which the SawStop technology only addresses one - it does not prevent kickback, which is the other most common source of injury. Often, it's the kickback that causes a hand to be drawn into the blade, but kickback alone can cause serious injuries such broken bones and eye damage or loss, as well as less life-changing but still severe bruising (which very often goes unreported). It turns out that a good solution to both of these problems (blade cuts and kickback) is one which already exists on nearly every new saw sold, and which costs very little to implement or even retrofit: the blade guard. It's included on every saw sold, and most tools now include a riving knife; even those which don't include at least a splitter. Usually, there are also anti-kickback pawls in the blade guard. There are a few cuts in which the guard cannot be used, but these are usually non-through cuts (such as a dado) which don't expose the blade anyway. Also, the anti-kickback pawls aren't 100% effective, but their effectiveness is probably better than 90% depending upon the material being cut. With the guard properly in place, there's very little chance of accidentally contacting the spinning blade. So why isn't this enough? I believe the answer is education, and possibly some much less expensive modifications to the existing guards. The culture of table saw usage seems strongly against the use of the guard, because: "It gets in the way"; "It takes too long to put on after a dado cut"; or the worst "All the YouTube videos show it removed". In addition, often the guards really are poorly designed, so that they are in the way or are difficult to remove and re-install. If these relatively minor design problems were addressed (one need look no further than SawStop's own implementation on their CTS for an excellent model), the overwhelming majority of table saw injuries could be prevented. This opinion is not solely my own. Jim Hamilton (of the excellent "Stumpy Nubs" woodworking YouTube channel) says essentially the same thing in one of his videos, and in generally he's an avid supporter of SawStop. I have no doubt that the number of table saw injuries will (eventually) drop significantly if the legislation passes, but that may be in no small part because table saws are being kept out of reach of a large number of potential buyers. In short, I believe nearly the same gains in safety could be achieved at far lower financial impact with better guards and better education (although I don't know the best way to achieve the latter...).
Mark Moulding
2024-04-11 04:00:26 +0000 UTCMy initial humorous--IMHO--take on this topic is: Using AI to keep you from losing fingers to a table saw?! Have you seen how AI art depicts human hands--most images are rendered with at least six fingers or more on each hand. What would a system like that do when it sees a 5-fingered hand approaching a whirling saw blade? Why would it care about how many fingers you have after using a table saw if it doesn't know how many you had in the first place? More seriously there should be a better way to produce safer power tools than SawStop as well as one that doesn't grant a monopoly to the only company that is authorized to sell a product mandated by law.
Mark Hesse
2024-04-10 14:57:50 +0000 UTCI've been going back and forth about selling my Delta table saw and buying a SawStop. I worry every time I use the tool... When I was in High School I was helping my dad with a woodworking project and I saw him cut off the tips of his left hand. I wish there was more than just the one option.
C Genco
2024-04-10 13:06:09 +0000 UTCThe Altendorf system that uses camera sensing is a very good example of a very expensive system.
Michael F Barushok
2024-04-10 03:14:23 +0000 UTCYour idea seems like a much better one than the conductivity trigger. Both sound like they'd make machinery a lot more expensive... but I guess it's worth it to keep one's fingers attached. π I wish you'd left the camera fall in! π
Motten
2024-04-09 20:52:52 +0000 UTCAlways interesting Fran. I'd never heard of saw stop, but it seems that table saws so equipped are now available in the UK.
Bob Pockney
2024-04-09 18:50:27 +0000 UTC
