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."

Comments

Good product

[dave-tx]

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.

always two sides to every story

[Anonymous Coward]

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.

This has been around for years

[RembrandtX]

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.]

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 .. 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.

Destroying the blade of course. which .. at $50+ a pop .. kinda hurts.

Another reason this hasn't been adopted yet is that pressure treated wood also tends to cause the brakes to fire off ..

This has been out for *years*.

[Chirs]

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.

Safety aside.....

[Sergeant Beavis]

Its actually a pretty damn good saw. I've used the SawStop cabinet saw at a couple of demos and I've been impressed with it. Losing a digit is always a concern, but anyone with a healthy respect for their tools will come away with fingers intact. Kickback is a much more dangerous situation because it can happen even when you are being careful. The SawStop has a self adjusting Riving Knife that prevents wood from binding against the rear of the blade and thus being thrown back at the end user. I've been into woodworking since I was 5. I've gone to many church and house rasing to help others and still volunteer my skills to Habitat for Humanity. In that time, I've been fortunate to keep my digits, but I've experienced the pain of kickback once. I was lucky to have gotten away with just a bruise. Kickback can flat out kill a person. Riving knives are very common on European built table saws, but are rare in the American market. We usually get a splitter with kick back cawls that should catch the wood as it gets kicked back. Normally it works well but a Riving knife prevents kickback in the first place. I can't think of one other US manufacturer that offers it on a cabinet or contractor saw. Saw Stop includes it on all of their saws.

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.