Startling at the Least, Injury- Causing at Worst, Kickback Can Happen on A

Kicking Kickback tartling at the least, injury- causing at worst, kickback Scan happen on a variety of tools when a fast-spinning cutter grabs the workpiece and throws it back at the operator. Understand- ing why it happens is the first step in preventing damage to your tools, project parts, and body parts. Then by tuning and using your tools properly, you can prevent it. In this article, we’ll look at four tools prone to kickback: tablesaw, router, mitersaw, and jointer. Regardless of the tool, always keep blades and bits sharp and clean to reduce friction. That keeps the cutter moving easily through the wood instead of grabbing at it, and contributing to kickback. 46 WOOD magazine Dec/Jan 2012/2013 Tame the tablesaw hen mentioning kickback, wood- knife or splitter prevents both the cutoff Wworkers often think of the tablesaw and the keeper from wandering into the Give kickback first because it can turn small or large blade’s rear teeth. During a ripcut, these the cold shoulder workpieces into powerful projectiles. devices keep the kerf open as the board Some saw blades and router bits have a How it happens: At the rear of the passes the rear of the blade. built-in shoulder in front of each cutting blade, the spinning teeth trace an upward The blade you choose can also make a edge to reduce kickback. The shoulder arc as they emerge from below the table. difference. See Give kickback the cold limits the depth of the cut, as shown in the A warped board, a misaligned rip fence, shoulder at right for details. photo and drawings below. operator error, or internal stresses in a If you hear a telltale “zing” at the On tablesaw blades with more than 50 teeth, the close spacing of the teeth workpiece can push the workpiece into completion of a cut, that indicates a mis- precludes the need for shoulders. the path of these teeth. This action lifts aligned blade. Adjust both the blade and and pulls the workpiece further into the the rip fence parallel to the miter-gauge teeth, accelerating the workpiece up and slot. (Refer to your owner’s manual and back toward the operator. More Resources on page 50 for help with Antikickback shoulder How to prevent it: Use a riving knife this process.) With these three parallel, or splitter to prevent boards from con- boards won’t pinch between the fence tacting the teeth at the rear of the blade and blade during ripcuts, and when The shoulder behind each tooth on this [Photo A]. With crosscuts, the riving crosscutting, the material contacts teeth 24-tooth rip blade limits how deeply the next only at the front of the blade. tooth will cut. Even with a well-tuned saw, much still COVER YOUR BLADE’S BACKSIDE STANDARD BIT ANTIKICKBACK BIT rests on your technique. During ripcuts, use featherboards or hold-downs when- Rotat io n n ever possible to press pieces against the o i t a fence and table just ahead of the blade. t Riving knife o Choose a pushblock that provides stable R downward pressure while gripping the workpiece firmly to provide the greatest control [Photo B]. Uncontrolled cut Depth of cut limited to 1.1mm (.043") When crosscutting, never use the rip fence as a stop;STANDARD the offcut, BIT trapped ANTIKICKBACK BIT between the blade and fence, will be Rotat io n n thrown back at you. Instead, make an o i t a L-shaped standoff block and clamp it to t o the rip fence in front of the blade [Photo R C]. This allows you to cut multiple pieces A During ripcuts, a riving knife prevents the to the same length and creates space so workpiece from moving away from the fence and the cutoffs stayUncontrolled safely away cut from the Depth of cut limited to 1.1mm (.043") contacting the rising teeth that cause kickback. back of the blade. MAKE A PUSHBLOCK FROM SCRAP GIVE ME WIDE OPEN SPACES Pushblock hooks L-block behind the workpiece. 2" B C A long notch in one edge of a scrap creates a hook that helps you push the Clamp a 2"-long L-block to the rip fence; then set the fence to account for workpiece down, forward, and against the fence. the 2". Butt the workpiece end against the L-block before starting the cut. woodmagazine.com 47 Don’t wrestle your router ver feel like you’ve gone three rounds fastest safe speed (Router-Bit Speed Chart, from the bit. Rest the workpiece against Ewith your handheld or table- below) that provides good results on your the starter pin or the end of the scrap and mounted router? That unruly behavior workpiece. Also, rout large profiles or slowly pivot the board into the spinning results primarily from poor operator deep cuts in several passes, increasing bit, so the depth of the cut increases technique —and that’s an easy fix. the bit’s exposure by 1⁄8" with each pass. gradually and controllably. After the How it happens with a handheld How it happens on the router table: workpiece contacts the bearing, you can router: Trying to remove too much Starting a freehand cut with a bearing- pivot the piece away from the starter pin material bogs down the router, slowing guided bit [Photo D] is a surefire recipe and continue routing. the bit. With reduced momentum, the for kickback. As the cutters bite into the As with a handheld router, foreign cutter hammers rather than slices the wood, the bearing doesn’t yet contact objects, knots, or spots where the grain wood, and kicks the router away from the edge. Because the workpiece lacks changes direction can also cause kick- the material. The same thing can occur any support, the bit can dig in deeper back. In addition to using antikickback when the bit encounters a knot or a for- than intended and kick the workpiece bits at their fastest safe speed, and rout- eign object, such as a screw or nail. back. The greater the area of the exposed ing deep cuts in several passes, mount How to prevent it: As shown on the cutters, the greater the potential force of featherboards as hold-ins and hold- previous page, antikickback bits greatly the kickback. downs [Photo F]. These minimize the reduce the problem by controlling the How to prevent it: Install a starter pin chances and effects of kickback, giving amount of bite the bit can take. To fur- [Photo E] or, if your table insert doesn’t you more control and a better routed ther reduce kickback, run bits at the accept one, clamp a narrow scrap about 2" surface on the workpiece. DON’T DO THIS! FINGERS AND WORKPIECE IN DANGER A STARTER PIN PROVIDES LEVERAGE ! Starter pin D E With no way to control the workpiece or cutting depth once the wood contacts Until the workpiece contacts the bearing on the bit, the starter pin serves as a the cutters, the rotation of the bit will jerk the workpiece violently. fulcrum, allowing you to control how quickly the depth of cut increases. FEATHERBOARDS DO THE JOB ROUTER-BIT SPEED CHART Featherboards Bit diameter Maximum speed* (in rpm) up to 1" 24,000 11⁄8–21⁄2" 16,000–18,000 2 5⁄8–3" 12,000–14,000 3 1⁄8" or larger 10,000–12,000 F A featherboard’s slanted fingers resist any backward forces, helping you *Manufacturer’s recommendations take precedence over these guidelines. maintain control of a workpiece even if kickback occurs. 48 WOOD magazine Dec/Jan 2012/2013 Master the mitersaw revent kickback on your mitersaw by it from shifting. Because the cutoff has housing fully forward, above and in Pequipping it properly and polishing no hold-down, it will move safely away front of the workpiece. Start the saw; your technique. from the blade if it twists or bows. When then push the blade down and back to How it happens: Internal stresses using a stopblock to help cut pieces to make the cut. This pushes the blade into released during a cut, or a workpiece not consistent length, hold on to the piece the workpiece against the rotation of the held firmly against the fence or table between the blade and stopblock, or blade. Don’t pull the blade forward dur- during the cut, can cause a kerf to close secure it with a hold-down. ing a cut; it will want to accelerate across around the blade, pinching the blade. Using the right type of blade also low- the workpiece back toward you, like a Because the blade rotates toward the ers kickback chances. Choose a blade lugged tire digging into dirt. fence and the head of the saw pivots up with 60 or more teeth to reduce the bite Sliders can also make simple plunge and down, kickback throws the head each tooth takes. Specialized mitersaw cuts, like a regular mitersaw, without the upward. The board may also bounce blades also have a near vertical, or even blade traveling along the bars. Before back at you. Short cutoffs can jam negative, tooth-hook angle to prevent making a plunge cut, push the head between the blade and fence, or be the teeth from grabbing the work like a back fully, and lock it in position on the thrown through the gap in the fence. claw [Drawing]. Allow the blade to come bars to prevent any forward motion dur- How to prevent it: First, support the up to full speed before lowering it into ing the cut.

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