Tune-Up Your Tablesaw

When your car acts up, you know it's time to open the hood and make some adjustments. Likewise, if you don't keep your power tools in tune, the quality of your woodworking will almost certainly suffer. Or worse yet, you may be setting the stage for a nasty accident. To prevent such occurrences, and to maximize precision performance from your tools, we've developed a trustworthy guide to keep your tablesaw in tip-top shape.

You probably already have all or most of the basic tune-up tools: 8" and 12" plastic drafting triangles, a 4' level or aluminum rule, a set of SAE or metric wrenches (depending on the type of screws and bolts used on your machine), spring or C-clamps, a few shingle shims, and several pieces of scrap stock. You'll also need a set of feeler gauges for checking clearances. You can buy these pocket-size sets of thin metal blades in .001" increments at auto-parts stores and some hardware stores. These sets cost only a few dollars each, so it's a good idea to have an extra set or two for use as precision shims, too.

That's the low-tech list. For greater precision, consider investing in a dial indicator, such as the A-Line-It. A dial indicator measures dimensional differences as small as .001"-about one-third the thickness of a human hair. Accessories that come with the A-Line-It let you configure the indicator to perform many different tasks on several machines.

For tuning up a tablesaw, or any other saw that uses a 10" circular blade, you also might want to purchase a calibration plate. These are precision-ground blades with no teeth to get in the way of your measurements. A calibration plate also doubles as a disc sander.

Before you tune up any machine, examine its belts, pulleys, and bearings. Check belts for cracks, fraying, and wear. If the top of a belt is more than ¹⁄₈ " below the edge of the pulley, replace it. Even if the belt looks okay, remove it and inspect the pulleys. Look for a shallow groove on the pulley's inside bevel, where the belt makes contact. If you can feel a ridge between this groove and the portion of the pulley that does not contact the belt, replace the pulley. Worn pulleys shorten the life of your belts and bearings, and sometimes cause annoying vibration as well.

Finally, before you reinstall the belt, spin all bearings. They should turn smoothly and silently, with no detectable back-and-forth movement. A dial indicator can tell you the precise amount of movement. It should be 0. Up to .001" is acceptable, but keep an eye on them because any play at all causes bearings to wear faster.A few opening procedures

Begin your tune-up by unplugging the saw. Remove the blade so the blade, arbor flange, blade washer, and arbor threads can be thoroughly cleaned and inspected. Now, rub the blade washer and nut lightly across a sheet of 320-grit abrasive mounted to a flat surface such as a piece of plate glass. Any burrs or high spots will show up as bright, shiny areas. These should be flattened with emery cloth or a whetstone. Also check the blade's arbor hole, using a finger to feel for burrs. Remove any you find with a small whetstone. The same goes for any nicks or burrs you detect on the arbor flange. Finally, if yours is a contractor's saw, check and tighten all of the stand's nuts and bolts. Snug them up for rattle-free performance.

Now you're ready to get that saw in tune. Because each of these adjustments depends on the one that goes before it, make them in the order described here.

If you have a direct-drive saw, you obviously can skip this step. Multi-belt cabinet saws rarely go out of alignment, either. But contractor and hybrid models are prone to vibration that transmits directly to the blade.

First, check the motor's pivoting base. Its job is to tension the belt, and the pivot should only be free enough to let the motor swing downward as the blade lowers and upward as it rises. Now, if space permits, lay a straightedge against the outer edges of the arbor pulley and motor pulley as shown in the drawing below. If both sides of each pulley touch the straightedge, the pulleys are in alignment. If one or more points of the pulleys don't make contact with the straightedge, adjust the motor or pulleys until the straightedge lies flush against both pulleys.

If you can't maneuver a straightedge into your saw, you'll have to align the pulleys by eye. Crouch behind the saw so you can sight along the belt and pulleys with your dominant eye. (Close the other one.) Once they're aligned properly, be sure to tighten up the pulleys or motor mount.

Now check that the table insert fits flush with the tabletop. Most inserts have four leveling screws at the corners. Turning these screws raises or lowers the insert. If your saw's insert doesn't have leveling screws, you may have to file the underside of the insert to lower it, or use layers of masking tape to raise it.

Use an 8" drafting triangle to determine if the insert is flush. With a triangle, stand it on edge at 90° to the miter slot. First, bridge the insert at the front edge, and raise or lower the insert until it touches the triangle. Move the triangle to the rear and do the same. Finally, slide the triangle over the entire insert. If you feel it catch, lower the insert some more.

For accurate cuts and controlled handling of large workpieces, your tablesaw's extension wings should be perfectly flush with the table. Check this with a 4' level as shown below. If they're not flush, you'll need the level, a fine file or 220-grit sandpaper, a spring or C-clamp, and a set of feeler gauges you can use for shims. Begin by removing the wings and, with the file or sandpaper, gently radiusing the top edges of the saw table and wings. This removes sharp edges and burrs. Also sand off any paint on the mating edges of the wings.

Now, bolt the wings back on the saw, but don't tighten the bolts all the way. Let the wings sag, with a ¹⁄₁₆ " gap at the top where the wings meet the table. Place the level across the front edge of one wing and the tabletop. Clamp the level to the extension wing at the outer edge. Pushing the level flat against the table aligns the wing. Slowly tighten the front mounting bolt, keeping a close eye on the bottom of the level. If it lifts from the table as you tighten the bolt, the bottom edge of the wing needs shimming; if a gap appears at the center of the level, you need to shim the top edge. Check at a minimum of three points along each table edge. You need to do this because wings can bow along their length (even cast-iron ones). By shimming at three locations you can remove most, if not all, of any bow.

To make shims, insert feeler gauge blades one at a time directly above or below the bolt. Tighten and check the alignment. It may take some trial and error to find the right thickness. Once you do, cut enough ¹⁄₄ "-long pieces of the blade to fit above or below all the wing bolts. Repeat this process with the other wing.

For a saw to accurately crosscut and rip, its blade must precisely parallel the miter slots. A misaligned blade will force work into or away from the blade, causing burning or kickbacks.

To check your blade's alignment, remove the guard and splitter, and install your best blade or a calibration plate. Raise the blade or calibration plate to the top of its travel, then lower it slightly. (We've tuned many saws that slightly skew the blade at its topmost setting, which can throw off your settings.) Next, adjust the miter gauge to 90°, and set it into the slot on the arbor nut side of the blade. If your miter gauge fits sloppy in the slot, use feeler gauges to shim it snugly against the side of the slot nearest the blade.

Mark a reference point on the blade just below the teeth or gullets, and rotate the mark to the front of the table. Now, stand an 8" drafting triangle against the miter gauge, with the point lined up with the mark on your blade. Lock the miter gauge in place, slip a .010" feeler gauge between the triangle's point and the blade, take up all play, and clamp the triangle to the miter gauge. The feeler gauge should slide in and out without deflecting the blade. Remove the feeler gauge and rotate the blade mark to the rear. Slide the miter gauge to the rear-again lining up the point of the triangle with the mark on the blade-and lock the miter gauge in place. The same feeler gauge should fit. If it doesn't, try others until you determine how far your blade alignment is off. If it's more than .002", determine which direction the back of the blade needs to go.

The illustration, below, shows a "high-tech" way of checking blade alignment with a dial indicator.

Exactly how you get the blade into alignment varies somewhat, depending on the type of saw you have.

With cabinet saws, the trunnions and table are independently bolted to the cabinet, making adjustments easy. With these, loosen three of the table-mounting bolts as shown below, and tap the table into alignment with a mallet or hammer and a block of wood.

Direct-drive and contractor saws have a pair of trunnions bolted to the bottom of the table. To align these, you loosen the trunnions and shift them to one side or the other as shown below. We find it easier to move the rear trunnion assembly. Leave one of the front bolts semi-tightened and use it as a pivot. Using a piece of stock and a hammer, gently tap the trunnion in the direction you want to move it. For greater control over this adjustment, you also can shift the trunnions with an L-bracket trunnion adjuster like the one shown below. When the same feeler gauge can be inserted at the front and rear of the blade, the blade is parallel and the bolts can be tightened. After tightening them, check one more time to make sure the trunnion didn't move.

Built-in stops govern a tablesaw's 90° and 45° bevel settings. Check your owner's manual to find out where these stops are located, then use an 8" triangle to learn if they're accurately set.

First, raise the blade or calibration plate just shy of its highest position. Check the 90° setting by positioning the triangle on the table with one leg of the 90° angle on the table and the other against the body of the blade, taking care to avoid the teeth. If you see a gap at the top or bottom of the triangle, use the tilt wheel to move the blade until the gap disappears. Unlock the 90° stop, bring it into contact with its matching point on either the trunnion or lead screw nut, and relock the stop. With the triangle, double-check that the blade remains at exactly 90° to the table.

Set the 45° bevel stop in the same way, tilting the blade to the 45° position and placing the triangle with its 45° leg against the body of the blade. Again, check after you relock the stop to be sure it hasn't shifted.face, use the 90° settings.

To do its job properly, the splitter must remain parallel with the saw blade, in the middle of the kerf. To set the splitter, cut a thin piece of cardboard or plywood in half, place the pieces against both sides of the blade or calibration plate, and center the splitter.

For accurate cuts, check your miter gauge often. Place it on a flat surface, such as your saw's table, and use the 90° angle of a triangle to determine if the gauge is square, as shown below. To set the 45° left and right angles, use the 45° edge of the triangle to establish and lock in your miter settings.

Kickbacks, excessive sawdust, burnt cuts, and crisscross saw marks are all symptoms of an improperly aligned fence. But properly aligned, you might be surprised to learn, doesn't always mean that the fence should be set precisely parallel to the blade. Some woodworkers prefer to setting their fences .015" to .030" open at the rear. This helps prevents the workpiece from binding between the blade and the fence if the wood warps as you rip it. The big trick to aligning a fence is keeping it that way, which means you should probably realign it before every major cutting project. To make this an easy adjustment now and in the future, rip a 4"-long, ³⁄₄ "-thick hardwood block to the width of your miter slot. Then, cut this piece in half to get two 2"-long blocks.

To align the fence, fit these blocks into the miter slot at the front and rear edges of the table. Loosen the bolts that adjust parallelism, drop the blade beneath the table, and slide the fence against both blocks. (If you want to set your fence open at the back, at the rear, start with a .015" feeler gauge between the fence and block.) With the fence pushed firmly against the block at the front and the block (and feeler gauge, if setting it open) at the rear, lock the fence head. Retighten the alignment bolts on the fence.

Now remove the blocks, plug in the saw, and rip a test cut. Inspect the fence side of the ripped edge for burns and crisscross saw marks. If you find any, add a little more space between the fence and blade. If you need to add .030" or more space, replace the blade and recheck.