Popular Woodworking 2008-10 № 171, страница 33

past the Made. the wood will start to encounter a forward vccror of force (hat in turn will cause (he wood (o reac( by moving in (he direction of (he rotating blade or toward the operator (the ac(ion of kickback will be explained in my next arrick). To countcr these forces, engineers have built in "control" as a way (o manage (be undesirable effects of the wood when it comacts (he Made. The table itself, the fence, a miter gauge, standard guarding, specialty devices such as push sticks, feather-boards and hold-down devices, arc all grear ways (o control (he s(ock as i( meets the point of contact on a rotating blade. A well-designed machine provides or has available some type of"control" (o couiucr (he kicking and grabbing forces that nauirally take-place with routing cutters and provides the user with a clcar range of motion through the cnorc process.

Three Kinds of Exposure

Going back ro Winters' explanation of hazard and exposure, he says (hat by reducing (he exposure, you will reduce the danger level. Less exposure means less danger: more exposure means more danger. It almost doesn't ge( easier than (hat - and tha( should be (he golden ruk' of operating all power equipment in (he shop safely. Exposure at a table saw can have three meanings: blade height when (here is no guard being used, blade height with the guard and repetitive ness. (For the sake of argument let's just say that these rules apply to all blade types.)

Blade Height when No Guard is Used

Let's face it: No mat(cr what rules we establish for the tabk saw- when i( comes (o using your guard. mos( woodworkers. bo(h professional and novice, will a( souk- time remove (be guard(s) (o make certain types of cuts. Nothing good comes by removing a guard. If you violate my rules about never running a (able saw without a

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guard, (hen you must set some kind of rule as to how much blade exposure you will allow. Widi unguarded and exposed (hrough curs the best rule to use is "minimize, not maximize." Like the late Dr. Roger Clitic used ro say. "How high the blade should be above your work is a definition of terms: die difference between amputation and lac-eration." And if the Made is unguarded you might as well plan on boch kickback and Made coiuaa as a part of your fu(ure.

It is recommended tha( when you are making unguarded (hrough-cu(s (ha( (he Made be set about '/»* to '/■»" above the stock. However, keep this in mind: A( a lower blade sorting (here arc a considerable number of teeth in the cut that are moving in a substantially forward direction. Kickback forces can be transferred into the wood most efficiently with j low blade, and with a lower blade there is a greater distance between the rear of the blade and the splitter. Plus more teeth means more friction, which in turn heats (he blade and increases (he risk of burning (he wood.

Let's just make this whole issue simple: Always find a way to guard the blade: never use a tabk saw without the guard. The point of (he two photos above righ( is (o demonstrate that at the low blade exposure, (he blade will have three (cc(h in (he work a( (he rear of (he blade. A( full exposure, only two rear teeth are in the work. The trajecrory ar the low setting will have the teeth of the Made leaning 60° ort" vertkal. directed at the operator while at full exposure, the trajectory of the teeth is only 30® otf vertical.

Blade Height when Guard is Used

This may take you by surprise but a higher blade height helps the Made to run cooler. At (Ik* same time, it helps (he motor (o run more efficiently whik using less power. I've been (old (ha( if (he saw is adjus(cd jusi right, you will also gc( a cleaner cut wi(h a higher blade. This is why a( trade shows you always see (he "pi(ch man" running (he blade as high as possible when demonstrating his blades. Why don't they use their guards - bunch of dummies!?!

Think of this as well: Wi(h fewer

Tooth trajectory, hi the top plioto you tan easily ttt the trajectory of the blade's teeth and the (kveneSS cf the blade to the tphttcr. /Ifvtr, the teeth trajectory if fotuurd, tou\tn1 the opcrMiH .utJ tlte distance betuveti rite blade and the splitter lus widened.

teeth in the cut. (he transfer of forward energy is less efficieiu and a higher blade presents less ofa gap between itself and the splitter. All of a sudden. i( sounds like I'm recommending (ha( you run your blade as high as pos-sibk. but that's not (he case. Keep in mind (ha( a higher blade sorting produces more exposure and a greater danger level - only if the guard is no( in place. And (his discussion is abou( blade height with (he guards in place. With a guard acting like a barrier, the likelihood of the Made contacting your hand{s) from any direction, except straight in. is low. No pivoted or aftcrmarkct guard can prevent you from sliding your hand straight into the blade. So what's (he answer? The answer is (ha( a well-guarded blade can be set slighdv higher (han an unguarded blade.

Repetitiveness

The second type of exposure is in terms of repetitiveness. Each time you

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