Bosch has officially entered the limb-saving table saw market with the rollout of its Reaxx table saw, nationally available June 1 ($1,500). This portable 4-hp, 10-inch contractor's sits on a rolling stand and comes equipped with technology that stops the blade when it comes into with your finger or hand.
We wanted to see this flesh-saving tool in the flesh, and so Bosch representatives recently brought Reaxx with them to the PM office. It was an amazing experience. We wheeled the saw into the building's carpenter shop on the first floor, and after setup, we deliberately tripped the machine twice to judge its effectiveness.
For the first test we cut a soaking wet piece of pressure-treated lumber, the idea here being to find out whether the saw's flesh-sensing capacitive circuit interprets the moist lumber the same as it would a human limb. About midway through the cut, when the blade moved from the wood's dry exterior into the moist interior, there was a loud bang, about equivalent to firing a .22 caliber long rifle inside a closed room. The blade vanished. The saw reacts so quickly that your eye can't see the blade plummet down into the saw body. Bosch doesn't say how quickly the Reaxx reacts. All I can say is that it's faster than your eye can capture.
Next up was the famous hot dog test, a bit of engineering showmanship pioneered by the inventor of this technology, SawStop. The demonstrator slowly and gently feeds a hot dog into the blade and bang, the same result. The blade disappears and won't tear apart the meat.
This time our building carpenter, Bob Lucchesi and Bosch's Jim Bohn and Jim Stevens examined the frank. There was only the faintest evidence of , not even a cut. You could have put that hot dog on the grill and no one would have known that moments before it had made with a table saw blade spinning at 3,650 rpm.
How It Works
Bosch's saw establishes a low-voltage capacitive circuit between the user and a sensing device next to the blade. Flesh coming into with the blade shorts the circuit and trips the chemical firing mechanism of a cartridge housed next to the blade. The loud bang we heard was created by the cartridge as it fires a stopped pin forward; the pin knocks out a clasp that holds the spinning blade in position on a drop arm assembly. Once the clasp is knocked out, the spinning blade assembly free-falls into the cavity below the table, its journey accelerated by the blade's torque.
Once the cartridge fires, it's permanently disabled because the outward projecting pin prevents the saw from operating. To put the saw back into service, you disconnect it from its power source, depress a lever and lift the blade into position. The blade locks itself in at full height—all you do is lift.
From there, you unscrew the electrical cap above the cartridge's chamber and unplug the electrical lead to the cartridge. Since the cartridges come in pairs, all you do is lift the cartridge out, flip it, install the fresh cartridge into the chamber and reconnect the electrical lead. Screw the electrical cap back down finger-tight and turn it the last eighth of a turn with a small specialized wrench that comes with the saw. Once the cap makes firm metal-to-metal , you're almost good to go. Reset the riving knife to the correct height, reset the saw's "On" switch, and you're back to sawing lumber. There's no damage to the blade, and other than flipping the cartridge, there's not much to replace.
Bosch estimates that this process should take a minute. I would say that the first time you accidentally trip the blade (say, with a piece of wet lumber or by hitting a metal staple) it'll take you a couple of minutes to get everything sorted out and get the saw running. Either way it beats sawing into your thumb.
The Shadow of Litigation
Even if the Reaxx didn't have the injury-preventing mechanism, it would still be an impressive tool. Bob Lucchesi plowed through some rip cuts in red oak stair tread as I snapped photos, and the saw hummed through it, producing a glue-line quality cut (Photo 6). With outfeed extension support, soft start, on-board push stick storage, and a robust rip fence that Bosch calls Squarelock, you have a great saw. Put all of that on a gravity-rise stand and you've got a machine that can handle anything on a construction site and most of what you'll need for finish carpentry. With some practice, I'm sure you could do cabinet level work on the saw. (By the way, the Reaxx mechanism also works with any standard (non-wobble) dado blade, for people leaning in the direction of finish carpentry and small furniture.)
Having said that, the shadow of litigation hangs over the saw's announcement. SawStop sued Bosch last July, bringing its complaints to the US International Trade Commission and the U.S. District Court in Tualatin, OR. The company alleges patent infringement. (By way of full disclosure, we've actually presented awards to both companies. Bosch has received Editor's Choice awards from us at the National Hardware Show, and its table saws (and other products) have consistently done well in our tests. It also received our Breakthrough Award for miter saw innovation. In 2006 we awarded SawStop's contractor saw our Breakthrough Award for nobly bringing its technology to smaller saws used on construction sites and into a price range a hobbyist can afford.)
Basically, the Bosch tool uses a sensing circuit that's similar to the one SawStop patented years ago, but not identical. Where SawStop's technology jammed the saw by running a piece of aluminum into it, wrecking the blade, Bosch's cartridge system can save the saw blade. Whether Bosch's design is too similar is a matter for the courts. There's no way to know for now how the case will play out. What we can tell you is that testing a saw that won't cut through your finger is a pretty amazing experience.