Dado Blade BASICS Dead-On Dadoes, Grooves, and Rabbets Are Easy to Cut When You Know Which Type of Dado Blades to Buy and How to Use Them

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Dado Blade BASICS Dead-on dadoes, grooves, and rabbets are easy to cut when you know which type of dado blades to buy and how to use them. WOBBLE DADO A single blade riding on a hub. hile one of the most One downside of a wobble It adjusts for different widths. useful tools for cut- blade is that it may leave a cut Wting joints is a dado with a concave bottom. This can blade, selecting which type to be reduced by using a V-blade. It’s buy can be a little bit confusing. still a wobble-style, but instead it To simplify it, all you need to has two blades mounted on a hub. know is that dado blades fall into Adjusting the hub pushes the three distinct categories: “wob- blades apart at one edge, creating V-BLADE DADO ble” blades, “V-blades,” and a “V” that cuts a wide kerf. “stack” sets. Okay, now let’s get to my Two blades riding on a center Wobble blades have a single favorite:a stack dado set.It’s made hub, also adjustable. 1 blade that rides on a hub. The up of two /8"-thick outer blades hub has a couple of wedge- (trimmers) with additional chip- shaped adjusters in it. As you per blades that can be sand- adjust the position of the wedges, wiched between the trimmers to the blade actually tilts at an angle make wider cuts. to the saw’s arbor.And, when you Stack sets take a little more turn the saw on, the blade “wob- care in setting up, but the dadoes STACK DADO bles” back and forth to make a and grooves they cut will have wide cut — a dado, groove, or clean, flat bottoms with little Outer blades with chipper rabbet. chipout. If there’s a downside, it’s blades in between. I know this sounds a little the cost.They’re more expensive, strange, but it works. And by but if you want quality dadoes, I changing the amount of tilt, you prefer a good 8" carbide-tipped can vary the width of the cut. stack set.

Tip Tip trims trims side of .005-.03" !/8" !/16" side of dado thick dado cleanly. cleanly.

LEFT-SIDE RIGHT-SIDE TRIMMER TRIMMER SHIM CHIPPERS

TRIMMERS AND CHIPPERS mer blade. As long as you get the that’s the standard finished thickness To get the best performance from a two trimmer blades oriented this for 1" hardwood — sometimes stack set, it’s important to understand way (and the blades are usually called 4/4 or “four-quarter.”) how each part of the set works. marked “This Side Out”), the teeth The job of the trimmer blades is will cut crisp, square corners. INSTALLING A STACK DADO SET to create the sides of the dadoes or Placed between the two trim- There are a number of things to grooves.You’ll notice in the drawing mers are the chippers. Depending know about installing a stack set. above that these blades look pretty on the manufacturer, these blades First, when the blades are in place in much like standard table saw blades. have two or four teeth each. Their the saw, the carbide teeth of one 1 Each cuts a /8"-wide kerf. That job is simply to clear away the waste blade shouldn’t touch the teeth of means if you put both trimmers on left between the trimmer blades. the blade next to it. Not only is this the saw at once, and make a cut, All stack sets come with multiple hard on the teeth, but the plates of 1 you’ll end up with a /4"-wide dado. chippers. You can put in just the the blade won’t fit together tightly. Now take a close look at the inset number you need to get the desired This means the chippers should drawings above. Notice that most or width dado. If, for example, you be staggered around in relation to 1 all of the trimmer blade’s teeth are stack four /8" chippers, and one each other as shown above.And the 1 1 bevel ground with the bevels slant- /16" chipper with the two /8" out- teeth on the chippers should be 13 ing toward each other. That means side trimmers, you can cut a /16"- positioned next to the gullets (area there’s a right- and a left-side trim- wide dado. (Not so coincidentally, between the teeth) on the trimmers. MICRO-ADJUST USING SHIMS When using a stack dado set you can Recently, I’ve bought some shims get close to the width you want to cut that are precision manufactured for 1 (within /16"), but that may not be thickness. quite precise enough. One way to They come in two styles. Plastic Paper Plastic increase it just a hair is by slipping one shims are color-coded for thickness, or more shims in between the trimmer with a slot cut out that allows you to fit and chipper blades. it on the saw arbor without completely For years, I’ve made my own shims removing the blades from the saw. by cutting up playing cards, business Magnetic shims stick to the blades Magnetic cards, thin poster board, or kraft paper so they won’t fall into the saw or (upper left in photo). between the threads on the arbor.

Rabbet CLASSIC JOINTS MADE WITH A

Dado or groove DADO BLADE

Tongues

DADO JOINT Top and bottom Back panel of case fit fits into into rabbets. rabbets.

The next thing to consider is how it frustrating that most saws don’t many blades will safely fit on the saw. come with a metal dado blade insert. RABBET JOINT When you put all seven blades on at It’s an optional accessory you have to once, you have a lot of heavy steel buy, so I usually end up making my flying around. So you want to make own. But that’s not all bad since you sure everthing is secure. can make an insert that will fit tight To fit all the blades on your saw’s around the dado blades you’re using. arbor, you may have to remove the large washer. Even with it removed, ONE BLADE, LOTS OF JOINTS the arbors on some small saws may Okay,once you have the dado blade still be too short. So for safety rea- set up, what can you do with it? Cut sons, I never use a stack set unless I dadoes, grooves, and rabbets, right? LAP JOINT can get the entire nut onto the arbor. Maybe I should back up a minute Adjusting the exact width that and explain the difference between you want the stack set to cut can be a these terms. Both dadoes and grooves challenge. You can add (or remove) are channels cut out of a workpiece. one chipper at a time, but since the The difference between them is that a 1 thinnest chipper is usually /16" dado runs across the grain. And a (.0625") thick, that only gets you into groove runs with the grain. the ballpark. To fine-tune the dado If the cut falls right at the end or width, you’ll need to use shims. See edge, it’s called a rabbet. the box at the bottom of page 2. Now,take a look at the photos at BOX JOINT Adjusting the width of the dado right. These joints are all variations is only half the battle.You’re usually of a dado, a groove, or a rabbet and also concerned with the depth of were cut with a dado blade. cut. I like to start with the blade set Finally, take a look at the a little low.Then I sneak up on the exploded view drawing above. It’s a final height, making a test cut in a typical bookcase or cabinet with piece of scrap. dadoes, tongues, and rabbets.They’re There’s one last thing to consider all made with a dado blade. — the throat insert. I’ve always found TENON (MORTISE AND TENON)

From Workbench Magazine page 3 ©2002 August Home Publishing. One copy permitted for personal use. Other copies prohibited. All rights reserved. MAKING THE CUTS GROOVE Each different cut made with a dado blade requires a little different setup — and a slightly different technique. Rip fence GROOVE: Probably the simplest cut is a groove. It runs the length of a board as shown at left. The critical Set rip fence thing here is that the rip fence be set correct distance the correct distance from the blade. Dado blade from blade. Also, when cutting a groove be To keep the groove a consistent sure you’re working with flat stock depth, hold the workpiece and the workpiece is held down tight down tight to the table. Rip fence Dado blade to the table. Otherwise the groove will be an inconsistent depth. DADO: A dado is cut across the DADO 1 Auxiliary fence DADO 2 grain of a board using the miter on miter gauge Use rip fence gauge.An auxiliary miter gauge fence as a stop. screwed to the front of the miter gauge helps support the board and prevents chipout. I use a couple of different meth- Layout lines ods to get the dado located in the Extra-deep Layout lines correct position. One way is to raise notch the blade to cut an extra-deep notch in the auxiliary fence. Now the notch Dado blade Dado blade can be used to locate the path of the blade in the workpiece (Dado 1). Another method is to use the rip fence as a stop.To do this,lock down the fence so the layout lines align RABBET BOX JOINT with the blade (Dado 2). RABBET: Cutting a rabbet (or rabbets to produce a tongue) on the Auxiliary edge of a board requires using the rip Fence Auxiliary fence on fence (see drawing).To prevent dam- Indexing aging my rip fence, I usually clamp an key miter gauge auxiliary fence, made from a piece of scrap, to “bury” part of the blade.The Dado blade amount of blade that sticks out deter- Clamp auxiliary Dado blade mines the width of the rabbet. fence to rip fence BOX JOINT: To produce a box and bury blade in it. joint, the workpiece is stood on end and passed over a dado blade (see drawing). (Note: Never cut with a TENON: Cheek TENON: Edge workpiece standing on end unless it’s Auxiliary fence supported with a box joint jig or a tall miter gauge fence.) Use rip fence TENON: One way to cut tenons as a stop. for mortise and tenon joints is with a dado blade, using the rip fence as a Stand workpiece stop (Tenon: Cheek). A long tenon on edge. requires a couple passes, moving the workpiece laterally between each. After cutting the tenon faces Dado blade (cheeks), the workpiece can be turned on edge and the two remain- ing shoulders cut (Tenon:Edge).

Chipout on the face of the workpiece 1. Be sure blade is sharp. 1 when cutting across the grain 2. Make a light ( /32" deep) scoring pass first, then raise blade for full cut. 3. Check that trimmers are facing the correct direction. 4. Use zero-clearance insert. 5. Place masking tape over layout lines before cutting. 6. Use a stack set, not a wobble blade.

Chipout on the edge of the workpiece 1. Back up cut with an auxiliary fence attached to the miter gauge.

Depth of dado/groove is inconsistent 1. Hold workpiece down tight on top of dado blade with push stick when cutting. from one end of cut to the other 2. Use a featherboard on top of workpiece. 3. Be sure workpiece is flat, not warped. 4. Support long boards with infeed and outfeed tables.

Dado doesn’t have a flat bottom 1. Use a stack set, not a wobble blade. 2. Sharpen all blades of a stack set at the same time to maintain consistent size.

Dado is wider than all blades of a 1. Be sure teeth of one blade don’t touch teeth of blade next to it. stack set put together should yield 2. If using thin shims, check if they have fallen between the threads on the saw arbor (or use magnetic shims).

Dado is slightly narrower than needed 1. If using stack set, add shims (see page 2). 2. If using wobble blade, readjust.

Dado blade grabs workpiece and pulls 1. If using radial arm saw, push saw through workpiece, don’t pull it. it (especially when using a radial arm 2. Switch to a dado blade with a negative tooth angle. saw) 3. Switch to a special “safety” blade with anti-kickback ridges behind each tooth.

Burning occurs when cutting dadoes 1. Be sure blade is clean and sharp. 2. Check that rip fence is parallel to the saw blade. 3. Cut is too deep. Make repeat passes raising blade between passes. 4. Feed rate is too slow.

A TALE OF TWO BLADES While I was testing the grain of plywood. But with a slow ments with most stack sets).This is great stack dado blades, I feed rate, it was acceptable. Order it (No. for cutting dadoes to accept hardwood came across a cou- 141037) from Woodcraft Supply at (800) plywood that’s often a little undersized. ple of sets that were 225-1153 or at www.Woodcraft.com. The Jesada 108-240 Joint-Master is a little unusual.The I’ve been using the $179 Jesada 8" available from www.Amazon.com or first one (left) only stack set (right) for some time now and it directly from Jesada Tools at cost $54.99. cuts very cleanly and leaves a dado or (800) 531-5559 or How can they groove with a perfectly flat bottom. www.Jesada.com. even make a seven-piece carbide-tipped One of the things I really like about set (with shims) at this price? The answer this set is that it comes with six chippers is with fairly thin carbide tips and lower instead of five. The extra 3 quality brazing. /32" chipper allows you to cut Okay, but how does it cut? Actually, I dadoes without shims in 1 was surprised how cleanly it cut in hard increments of /32" (as maple — as long as I didn’t feed the work opposed to the more 1 too quickly. It chipped out some across common /16" incre-