Woodworker's Journal 2008-32-3, страница 74

Today's SHOP

The SawStop also includes a riving knife, to be used when you can't use The SawStop's blade is completely surrounded by a dust shroud, with the blade guard. It prevents wood from pinching in on the blade behind a hose going straight from the shroud to a port on the back of the cabinet, the cut. The riving knife maintains the distance from blade to knife. preventing you from filling the cabinet with dust.

The T-square style fence is solid and includes a nice feature called T-Glide. On many T-square style fences, the fence position changes slightly as you lock the fence, due to wiggle room between the lock and the fence rail. The T-Glide feature minimizes the gap between the fence and the rail. As a result, once you

locate the fence's cursor on the ruler and lock the fence, it stays put on the cursor location.

Will the Brake Break It?

Some woodworkers I talk to are concerned about potential negative effects of activating the brake, wondering if the sudden stop will

affect the saw's accuracy. The folks at SawStop told me, "In testing, we've repeatedly activated the brake mechanism on a number of our saws and haven't seen any negative effect on the saws' accuracy." Remember that these folks are pushing a hotdog into the blade many times a day at their demos,

How the

SawStop Stops

M hotdog, simulating a finger, is pushed into a spinning table saw blade on the SawStop machine.

As the hotdog touches the blade, the blade instantly disappears from view and comes to a complete stop.

The result is a nick that barely penetrates the casing of the hotdog.Total time from contact with the blade to the blade retracting and stopping is about 5 milliseconds, faster than the blink of an eye. If you've never seen the demo, you can now catch a video of it at the Journal's web site.

Here's how the SawStop technology does what it does.The human body is like a big capacitor, and is capable of absorbing electricity. A small electrical signal is put onto the saw blade on the SawStop saws. If you touch the blade, some electricity drains from the

blade to you, though not enough for you to feel any shock. A microprocessor built into the saw constantly monitors the signal on the blade and recognizes the voltage drop. Once the microprocessor sees the voltage drop, it activates the brake system. The brake consists of a heavy spring and an aluminum brake pad.The spring is held in compression by a fuse wire. When contact is made with the blade and the microprocessor does its thing, the fuse burns through, allowing the spring to push the aluminum pad into the spinning

If your hand ever comes in contact with the saw blade during use, a microprocessor senses a drop in voltage from the blade to your body and activates the saw's brake in approximately 5 milliseconds.

blade.This, of course, causes the blade to stop.The momentum of the blade suddenly coming to a stop causes it to retract below the table. At the same time, the power to the motor is shut off.

Removing the now all-in-one brake and blade combo can be a little difficult,

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June 2008 Woodworker's Journal