A Circular Table Saw That Won't Cut Off Your Fingers



(Video Link)

Pretty clever:

The blade carries a small electrical charge. This charge is continuously monitored by a digital signal processor. When contact is made, the human body absorbs some of the charge, causing the voltage to drop. The drop in voltage triggers a quick release aluminum brake. A heavy duty spring forces the brake into the teeth of the spinning blade. The teeth dig into the aluminum, stopping the blade cold. The blade's momentum forces it to retract below the table, and the motor is automatically shut off.

Via Geekologie


I'd like to know how they stop it from triggering on a large piece of high moisture-content wood.
Clever, though, even if it does need a new part once triggered.
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They are very expensive, but if I used a saw for a living I might want to have one. I know a guy who just took three fingers off in his saw. He had seen a SawStop demo just a couple of months ago and you can bet he wishes now that he'd had one.
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ha ha they have a lot of confidence in their product using suasages to demonstrate it!! I want to see what happens when you use a real finger!!! That tiny nick in the sausage could still cause a lot of bleeding!!

Maybe an experiment for Jackass to try out??
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This technology has been around for a long time. Companies did not want to license any technology that still aloud the user to get hurt (the nick in the sausage) even though you will not lose your finger companies didn't want use any technology that would open them up for more lawsuits. I believe the inventor of this technology had to start his own company.
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Having sliced a reasonable percentage of my thumb off with a tables saw I can see the immediate benefits of this. Wish they were around when I was working on them...
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Actually, they can't stop it from triggering. One of the problems with the system is that it can be triggered on wet woods- or any time the high frequency signal has been 'absorbed' or grounded from the blade.

An explosive charge fires a chunk of aluminum into the blade and destroys the blade in the process. The force of the blade stopping is what rotates it out of the way.

Blades run about 100$, the charge is expensive and the cost of the sawstop runs 500$ to each tablesaw. The inventor has been trying to lobby congress to pass a law that every saw sold has to carry his invention- which is why a number of home shop people do not enjoy the idea of this product.

Yes, I'd like one in the house. No, it will not be from him.
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Nice tool, but it is NOT a circular saw, it is a table saw (the original article misnames it).

Also, the inventor may have made a useful thing, but he is a greedy #%^@#$*: He wanted $1000 per saw to license his technology (more than doubling the price of entry-level tools). When no manufacturers wanted to screw their customers that much, he went to congress to lobby them to force them to buy it. I wouldn't mind having one, but not at that price, and not to enrich him unfairly.
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@Ray: high moisture content notwithstanding, wood in general is an aggregation of tiny airspaces, distinct cells and grain patterns and is a poor conductor overall. Especially compared to the electrolytic and contiguous blood and saline solutions flooding our fingers.

Plus, there isn't uch of a path to ground through a moist piece of wood (which registers perhaps 15-20% on a meter) on what I'm guessing is a ground insulated saw table.
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And oh yeah! - the mandatory safety law crap is straight up hucksterism. As a one time proctor in a teaching shop and a 20 year veteran as a journeyman carpenter, on the whole, IMO, it's better anyways to keep an alert and healthy respect for the power and demands of a table saw; something this cognitive bandaid and childproofing will dull and mitigate actually. After all, running your finger into the blade is only one of many dangers of running a table saw or any shop equipment, for that matter.
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The link reminds me a lot of this one:
http://www.neatorama.com/2007/02/04/the-worlds-safest-table-saw/

deja vu....

Neat idea, but pricey. Might be worthwhile for shop classes with lots of new saw users. That said, anybody who lobbies Congress for laws to MANDATE their product is a scumbag. Mandated safety in general sucks. It's a big reason why we drive very expensive overly heavy gas sucking cars. If not for the efforts of the Insurance Institute for Highway Safety, small 4 passenger cars would be available in the U.S. that didn't weigh 3200# and cost $25K. Give people choice, whether it be for tablesaws, vehicles or whatever. The public will value safety features by how deeply they dig into their pockets. Don't force us into anything...
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I think the damage done to a finger in the precess of this safety mechanism engaging would still be pretty severe. At least a trip to the emergency room though better than losing a digit or limb.
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This presents an interesting dilemma for, say, high school shop classes:
Replace expensive (~$600?) parts everytime some fool puts a finger/hotdog to the blade, or just let social darwinism run amok?

I guess the question is 'how much is a finger worth?'
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In reply to Cr--mp-nts and Gail, take a look at the video, there is a sizeable chunk taken out of the hot dog. If I were a product demo'r of this saw I wouldn't use my finger either.

And can someone change the title of this posting? I agree with BrianD - it's a "table" saw not a "circular" saw. Big difference - I came to this article because I thought SawStop came out with a product for circular saws (users of which, from my amateur carpentry background, are much more vulnerable to fingers getting cut than table saw users.)
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Let'see:

1 It's only $50 to $75 to replace the sawstop cartridge after it has fired.
2 The blades are not always destroyed and sometimes can be repaired.
3 If the brake is fired and it was actually a "save" and not a person putting a hotdog or edge of the miter into it, Sawstop will replace the brake cartridge for free when you send in the discharged cartridge for analysis.
4 There is a quick and easy method for testing of a material may set off the Sawstop brake. If saw says that it may fire the brake, a bypass can be entered with a key to override the protective circuits.
5 The sawstop is more expensive than a non-sawstop table saw. The Sawstop has many features and is regarded as one of the best quality saws made right now.

I don't own a sawstop, and I don't want anything mandated on me by the government, however, I If I had the money I would be using one right now.
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I work at a university. We purchased one of the first of these saws that they produced - we had to wait over six months or so for it. The company does not charge too much of a premium in price over the price of a high quality standard table saw. For workplace safety, this saw is well worth the cost. We haven't had anyone cut themself with the saw but we have triggered the mechanism with the following: wet wood glue, staples and carpenter bees. If you know you've got any of that stuff in the wood, then you can put the saw in bypass mode while you make your cut(s). The cartridges are around $75.00 each. The blade generally is not damaged by the mechanism. Our carpentry shop has used this saw extensively over the past three or so years. It is very well built. We haven't had any problems with it. Hopefully, the company has not decided to start cutting corners since they rolled out their first production models.
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Alright before you get all crazy about how good this saw is...and before you claim I don't know what I am talking about, I am a carpenter and have used really expensive industrial sliding panel saws, and cheap 100 dollar skil table saws with plastic bodies that wobble, even on level ground...

People who lose their fingers to a table saw do not know how to use it properly. There are either too many distractions, or they take stupid chances. I know a guy who was ripping a piece of wood, and while ripping decided to look at the clock above the door to his shop to check the time, and the next thing he knew, his finger was on the floor, and blood was everywhere. What's so hard about finishing the cut (takes less than 5 minutes) then checking the time?

I know another carpenter who almost lost a finger because he was ripping small pieces. The piece, when finished being ripped didn't fall off the table, and he decided to try and lift it out, instead of turning off the saw, then removing the piece.

If you are going to buy a table saw (this goes to all those who think by going to the home depot, or working a summer with a carpenter when 16, they think they can do any renovation or form of woodworking), I highly suggest you read the manual, get a book on the machine, and if the option is available, take a class of some sort on safety and power tools.

I have an uncle who worked in a lumber mill, and a table saw operator who didn't listen, and wanted to rush production ended up dieing because the piece of wood kicked back on him and ended up piercing through his abdomen. Of course, it was an industrial saw for milling lumber which the average joe cannot afford, but even the cheap table saws are powerful enough to make you feel like you've been shot in the stomach.

I agree with safety features such as a transparent guard (not translucent), anti-kickback fingers, a splitter, and a riving knife. But a safety feature like this basically means you will be less careful, and "lose respect" as I say, for the machine.

Oh, and for the price for one of these (3000-5000), you're better off investing in something else in terms of a good quality table saw. For 3000 dollars you can get an entry level full sheet sliding panel saw, which is in the end a safer, more powerful, and better quality saw.
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It really is one of those things that you wish you had before something bad happened.

If only they could do it with circular saw and miter saw since it's far easier to chop off your fingers with those tools rather than a table saw.
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these things can still kick back. last year a girl in my construction class made the rip fence too close to her piece and wasn't pushing the side that was between the rip fence and saw. the thing flew like a bullet and made a dent on one of the steel support beams in the class.

and when the saw stop kicks in, you wont realize it until a minute passes by. it just slams down and disappears while you think your still cutting. i somehow set it off because of the miter gauge just touching the blade by just a millimeter
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Or you could pay attention to what you are doing and get the same result. Actually, paying attention to what you are doing will not usually result in nicked hotdogs. Usually.
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To Roadnate;
Dude after cutting thousands upon thousands of the same size pieces of wood per day you tend to get lulled into a bit of a fall sense of security. It's not always that easy to pay attention to what you're doing when your boss is on your back demanding you go faster...
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I've just looked at their website and see that they've posted some photos of fingers and thumbs that have triggered the saw. They've got a pretty good nick but nothing compared to losing part of your body. My friend's father just cut part of his thumb off with a table saw. I do agree with those who say that this should not be mandated by the government.
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