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Skin Sensing Table Saw
killabrew writes "Check out this article from Design News about a new skin sensing table saw technology that is on the verge of becoming a mandatory piece of hardware on every table saw. For years inventor Stephen Gass persevered in the face of legal, corporate and technical foes, he is forcing society to rethink its acceptance of saw blade accidents."
http://science.slashdot.org/article.pl?sid=04/06/3 0/131241
Which was probably duped again earlier.
Quick, go steal some +5 comments from that one!
http://science.slashdot.org/article.pl?sid=04/06/3 0/131241
Here is a writeup of the saw's debut at the International Woodworking Machinery & Furniture Supply Fair (2000). I remember reading this back in 2000 thinking "great idea, but I wonder if it'll ever get adopted". Glad to see it's gaining traction - the table saw is the only piece of equipment in my shop that I'm nervous around.
Now if they can solve kick-back, I'll be a tablesaw fiend.
>> "What would the robut do? Frame someone!"
As someone who was involved in evaluating this technology for a major US manufacturer of power tools, there are a number of issues which prevented early adoption. First and foremost was the inventor's demands for unreasonable royalties (including a percentage of the gross sales of table saws from preceding years!). I heard the director of the power tools group say that if the royalty had been reduced by 50%, it would have been a no-brainer. As it was, the proposed royalty structure was just unsupportable for a saw that sold for $500.
The second issue was that the product had great difficulty distinguishing the change in capacitance due to human flesh from that due to very wet lumber. This has undoubtedly been improved over the past few years, but people would have been somewhat unhappy to have false triggers that required them to a) replace the safety cartridge and b) their saw blade, which is consumed when the system triggers. Not to mention having the bejeesus scared out them when the system fires in error.
To talk about the inventor persevering in the face of corporate pressure is silly. This isn't a David vs. Goliath story. The inventor was a patent attorney that tried to bludgeon power tool companies with a 250+ page patent, and he could have sold his concept on day one if he hadn't been quite as greedy. There was no shortage of companies looking for competitive advantage in the power tool industry, which has been pretty stagnant of late.
I forgot the link to the SawStop site
http://www.sawstop.com
If you think it's expensive to hire a professional to do the job, wait until you hire an amateur. --Red Adair
No Problem.. Get your $3,000 ready and go here
http://www.sawstop.com/
If you think it's expensive to hire a professional to do the job, wait until you hire an amateur. --Red Adair
Its been around for years, and has been shopped to the major power tool manufacturs [one of the largest, I used to work for, so i'm not talking out of my butt here.]
.. the guy whipped a raw hot dog at the blade as fast as he could, and there was only maybe 1-2mm of damage to the hotdog before the blade dropped down into the brakes.
.. at $50+ a pop .. kinda hurts.
..
All of them turned it down due to legal implications, as well as adding to the cost per unit price.
Leagally, if a power tool manufacturer added this to their existing line of table saws, it *COULD* be taken as an admission of guilt that their previous models were not safe, any accident cases (no matter how stupid) would then have another chance at a successful suit.
Also, the inventor has been lobbying for *YEARS* to get his invention as a required component of table saws. He hasn't even had success in California - the most liberal state for passing stuff like this - let alone elsewhere.
I'm not knocking his invention, I've seen it pitched first hand
Destroying the blade of course. which
Another reason this hasn't been adopted yet is that pressure treated wood also tends to cause the brakes to fire off
--Ne auderis delere orbem rigidum meum, non erravi pernicose!
Well our bodies give off an electical charge (which is very close to a hotdog) and the blade being metal. So when it hits our skin a low level electic charge is shot across the blade into a chip that determins if it is the same electical change as a human hand. If it is then it fires a stopping pin that breaks the saw very fast, and allowing it to only scratch the finger, mind you it will be a deep scratch, and will hurt like hell but it will heal in time and with a banage you can continue with work that day.
As for the slasher movies, I am sure they can just take out the breaking pin, and they will be all set. Heck it allows for 1 more minute of the movie to expand it plot.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
For the non-woodworkers in the audience, this tech has been available for several years, and information on it was available for at least a year before the saw itself.
The "Sawstop" modifies the electrical potential of the blade, and can thus detect when skin hits the blade. Of course it also triggers if you cut metal, so it has a disable switch. Apparently wet wood doesn't trigger it.
When it detects flesh, it has an explosive charge that rams a chunk of aluminum into the blade stopping it within ~3ms. I saw it demoed in person at a wood show. The demonstrator slid a hot dog into the blade at a fair speed and there was a large bang. The hot dog had been cut into maybe 1/32" or so (a bit under a millimetre).
The main problem is that the inventor wanted huge royalties from existing tool companies, and tried to force through legislation making it mandatory to include the device on *all* table saws in the US. As you can imagine, people were less than impressed about having it rammed down their throats. Even now, the saw that incorporates this is a very nice saw, but they still charge about 30% more than for other comparable saws.
Not only that, but if for some reason the device acidentally trips, you're out a whole lot of cash replacing the blade, brake shoe and no telling what else. For someone who can afford a $2000 cabinet saw, this may not be that large of an expense, but for the average person doing this as a hobby, we tend to pinch every penny. Heck, I've been doing this as a hobby going on 10 years, and I can't justify to SWMBO why I need a dado stack for my saw. If I had to buy a new saw with this technology, I'd have to give it up, given the cost of the saw and repairs. Plus, a little common sense would almost reduce the need for this completely. Use a push stick when ripping narrow stock. Use feather boards where appropriate. Use a miter sled when cross cutting. If possible, leave the blade guard on (not easy...my previous saw was safer without the guard due to a crappy splitter on the guard). If you have to, paint a red line in front of the blade on the saw table showing where the blade is. Paint a perpendicular one showing where the throat plate starts. Don't stand in front of the blade if you don't have to. And, if you don't think it is safe to do the operation, then DON'T DO IT. And yes, before I am asked, I've not followed all the rules myself. I did get a very bad scare about 3 years ago. I was cross cutting something, and felt a really strange vibration on the tip of a finger. I looked, and somehow I had gotten the tip of a finger past the teeth on the blade, and my fingertip was resting on the side of the blade while spinning. Fortunately for me, I was not injured, and since then I have tried my best to make sure that I never have that situation again. I have found a great resource for all sorts of shop info, including safety. BT3Central.com has several forums. The forum was created for owners of the Ryobi BT3x00 saws, but anyone is welcome. I have gotten lots of advice and inspiration from there. We all pretty much agree that the idea behind the sawstop is a good idea, but not that practical given its cost. Like I mentioned earlier, most of us would have to give up our hobby if we had to buy one.
"It's a dog eat dog world out there, and I'm wearing Milk-Bone underwear."- Norm (from Cheers)
All they have to do is turn the key on the side of the unit that "disables" the safety feature.
It comes standard on the saw.
Some friends of mine own a Scene Shop that makes sets for Stage Productions and they bought a pair of these a couple of years ago.
Being a Scene Shop, they don't just use the saws to cut wood, they also cut Acrylic and Aluminum.
They HAVE to disable the safety feature to cut Acrylic and Aluminum or it triggers a False Positive and that quick cut ends up costing $150 to replace the blade and the soft aluminum block that slams into the blade to stop it so fast.
so far ALL the replacements have had to be done because the employee forgot to DISABLE the safety system when they were cutting something other than wood.
I like microcars
In the US a safety that could be disabled by wedging cardboard in it wouldn't get past OSHA. They have thought of that and require the buttons to cycle, so you cannot just wedge it. I believe that in Europe, light curtains are also used. They are used in the US too, but not by themselves, because OSHA has very high standards for a light curtain system.
r elpath=/pages/content/en_US/setonalerts/articles/0 904/0904_mach_safeguard.jsp
This is a good summary of the issues: http://www.seton.com/seton/internalHtmlAction.do?
I've actually seen a demonstration where the president of the company used his own hand. Quite a show of faith in your product, I have to say, and very impressive as a selling tool.
Slashdot needs a "-1, Wrong" moderation option.
The Urban Hippie
We actually have one of those saws (Sawstop - I assume that's what we're talking about, the link times out for me) at work. It's $65 for the "cartridge" and the cost of the blade. So about $150 - $200. Seems cheap insurance compared to the $35,000 lawsuit some guy brought against us a few years ago for cutting his hand up in a regular 10" tablesaw, which was entirely his fault anyway. And it's a hell of a lot less than "a new tablesaw", which for a good one (not even a Sawstop brand) will cost you $1000 - $2000. Not trying to be a dick or anything, but they've come down a LOT in the last couple of years.
That said, personally, I'd rather take your suggestion of "it's dangerous, be careful". There are plenty of safety devices for tablesaws that work, most notably a pushstick and a bladeguard with a vacuum attachment. They jury's still out on splitters, though, I run into about 50/50 when I ask people their opinion on them. I can't say as I've ever used a saw that actually had one on it, though, so maybe that's saying something.
This is a fantastic saw. I don't know about the skin-detection feature, but it is the first american saw with a riving knife (before PowerMatic), and it has a European style shrowd covering the entire blade. Not to mention the beefy trunion. Even without the safety feature it is a great saw. Now if we could start getting some sliding top saws like they have in Europe...
https://www.accountkiller.com/removal-requested
As someone who was involved in evaluating this technology for a major US manufacturer of power tools, there are a number of issues which prevented early adoption. First and foremost was the inventor's demands for unreasonable royalties (including a percentage of the gross sales of table saws from preceding years!). I heard the director of the power tools group say that if the royalty had been reduced by 50%, it would have been a no-brainer. As it was, the proposed royalty structure was just unsupportable for a saw that sold for $500.
So, you were involved in evaluating it- but have absolutely no specifics about "the inventor's" demands? How much was the percentage? How many years back? What was the royalty "demand" on products sold with his technology? Do you have any evidence to back up your claims?
The second issue was that the product had great difficulty distinguishing the change in capacitance due to human flesh from that due to very wet lumber. This has undoubtedly been improved over the past few years, but people would have been somewhat unhappy to have false triggers
People don't cut wet lumber. Firstly, you shouldn't use it, unless it is dry, or you'll get problems when it dries out (and/or mold when it gets covered up.) Second, because the blade binds in wet wood.
Please help metamoderate.
My dad once butchered an animal (beef, I think) and left in the barn to cool. He couldn't get to it for a few days and it froze solid (Minnesota winter). He needed to cut it into smaller chunks to be able to carry it inside for cutting up. So he thinks: chainsaw!
:-(
Much of it had to be thrown out due to all the bone chips.
science is a religion
"better make sure the wood you are sawing isn't damp"
An interesting guess but wet wood (which you REALLY shouln'd be curtting) isn't going to have the same electrical properties as wet salty flesh which is MUCH more conductive.
Mmmmm... wet salty flesh...
Need Mercedes parts ?
Outside of those items, the SawStop is also very well balanced, it has almost no vibration, even less that most other Cabinet Saws. The trunions are solid and move the blade into position with little effort from the user. It also has a magnetic cutoff switch positioned right above the users knee for quick shutdown. It also includes a Biesemeyer style fence. Its only real drawback is that it is very expensive at $2800 for the basic saw. Options can run well over $5000. While I still like it, that money could be better spent on a European Combination Machine such as the Laguna or a Delta Unisaw with alot of money left over for other tools.
There is nothing inherently safe about liberty. That's why so many people died protecting it.
You'll have to excuse me if I post anonymously, my department would likely dismiss me were it to appear I represented it in any way.
Good Samaritan laws specifically do not include trained providers. An off-duty Paramedic or off-shift Doctor passing an accident scene who stops to assist, or even asks such an innoculous question as, 'How are you?' - regardless of answer - could be construted as initiating a patient care relationship.
Once that relationship has been established, the provider is now legally liable, and has both the onus and duty to act in accordance with all applicable protocols, laws and standard(s) of care.
Good Samaritan laws protect, with some notable exceptions, John Q. Public from non-, mis- and/or malfeasence in the above protocols, laws and standards of care with respect to rendering care to the sick or injured in a state of emergency.
Example:
A car has been involved in a crash, and an unresponsive driver is slumped over at the wheel.
John Q. Public pulls over, rushes to the vehicle and shakes the driver's shoulder to see if he is concious. Unfortunatly, the driver has sustained a lasting spinal injury - neither the driver nor driver's lawyer would have no claim against John Q. Public, regardless of John Q. Public's actions which may or may not have been proximal to the injury, due to the Good Samaritan law(s).
Same scenario as above, but change it to an off-duty Paramedic. The Paramedic, by virtue of his training, ought to be aware of cervical spine considerations, and precationary measures to be taken when circumstances dictate them likely and prudent. The Paramedic, by acting, now bears the onus and duty to act, has performed an act incorrectly as per the action(s) of other similarily trained providers, an injury resulted, and is arguably proximal to the damaged. By any measure, the off-duty Paramedic bears a significant liability which will certainly be argued in front a judge and/or jury.
The only Good Samaritan exemptions enjoyed by trained providers are those in which either (1) the trained provider does not function to his level (i.e., extraordinary measures - a field C-section), or is not functioning in his realm of expertise (e.g., a Paramedic with no fire fighting experience attempting to supress a fire), or (2) performs all skills correctly and within the accepted standard of care. The legal rigor of 'all' in (2) is extreme, to be generous.
And yes, we spend a tremendous amount of our time continually studying not only new science and medicine, but also medicolegal subject matter to protect ourselves, our departments and our profession.
These things have been available in industry for a few years now. My wife works as a chemist for a major wood products company. They got this table saw last year.
The replacement parts expense isn't nearly as bad as it's been made out to be, either. They accidentally triggered the 'quick stop' feature the other day -- not with a finger, but sawing some wood that was too wet and therefore coincidentally had the right electrical properties. Replacing the blade turned out to be about sixty bucks.
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