With the tablesaw, you can rip and crosscut lumber to size, cut straight edges on boards that have none, and also cut many types of joinery.

Advertisement
DB_0648.jpg

For many of us, the tablesaw proves to be the cornerstone of building most projects. With this machine, you can rip and crosscut lumber to size, cut straight edges on boards that have none, and also cut many types of joinery. In this article, we show four joints you can easily create on your saw using a miter gauge and rip fence (and a few other accessories: See Sources, at end of article.)

For all of the joints in this article, always make test cuts in scrap stock to perfect the setups before machining your project parts. And in most cases, using a zero-clearance throat insert on your tablesaw will produce cleaner and safer cuts.

Half-lap

DB_0644.jpg

Best uses: any type of frame (picture, door, face frame)

A half-lap, shown above, consists of rabbets, dadoes, or grooves cut to half the thickness of mating workpieces. This joint lacks mechanical strength, but gets its strength from long-grain to long-grain bonding with glue. You can cut a half-lap joint in two ways on a tablesaw.

Using a single blade

You can cut half-laps best with a 40-tooth general-purpose or 50-tooth combination blade. This method cuts cleaner, smoother cheeks for stronger glue joints.

DB_0634.jpg
Cut the shoulder first, using the rip fence as a stop.
DB_0636.jpg

Using a dado set

Start by installing a stacked dado set; in most cases, the wider the better, because you can remove more material with each pass. Install an auxiliary fence on a miter gauge to combat tear-out where the blade exits the workpiece.

DP_0638.jpg
Raise the dado blade to about half the workpiece thickness, and then cut away a short section on one face of each of the mating workpieces.
DB_0640.jpg
Test the fit, adjust the dado height, if necessary, and repeat until each board is precisely half the thickness (for a perfect fit).
DP-0641.jpg
Using the rip fence as a stop, make the shoulder cut. Lift the workpiece, retract the miter gauge, and reposition the workpiece to cut away the remaining material between the two cuts with one or two passes.
DB-0643.jpg
A dado blade leaves a semi-rough cheek, a good, but not great, gluing surface.

Tongue and groove

Best uses: edge-glued panels (tabletops, door panels, etc.), carcase backs, frame-and-panel doors

A well-made tongue-and-groove joint maximizes linear-edge glue surface while also providing goof-proof alignment of the mating workpieces. As with a half-lap, you can cut a tongue-and-groove joint with either a dado set or a single blade. In both cases, cut the groove first, and then cut the tongue to fit snugly.

DB_0652.jpg

Using a dado set

Install a stacked dado set equal to or slightly narrower than the width of the groove you want to cut. Be sure to use a zero-clearance insert—you'll need workpiece support on each side of the blade.

DB_0647.jpg
DB-0648.jpg

This hybrid tongue and groove is an open-and-shut case

DP-1630.jpg

Stub-tenon-and-groove joints find use primarily in doors and similar frame-and-panel construction in lieu of using cope-and-stick router bits. Cut this joint in the same manner as a regular tongue-and-groove joint, but with the tongue on the ends of a workpiece, usually the horizontal rails. Cut the groove first, sizing it to fit the door's panel. Then, size the tongue to fit the groove.

Using a single blade

Blade kerf (thickness) doesn't affect the quality of the cut, but thin-kerf blades might require more passes than a full-kerf blade.

DB_1327.jpg
Rip a groove to one side of center, then rotate the board end for end, and rip again. Adjust the fence, if needed, and rip both sides of the groove again to get the desired width.
DB_1342.jpg
Without changing blade height, reposition the fence to cut each side of the tongue.
DB_1350.jpg
With a handsaw, trim the tongue-board corners so you can test the tongue's fit in the groove. Adjust the fence and shave both sides of the tongue until it fits snugly.
DB_1355.jpg
Lower the blade until it just grazes the tongue of the tongue board, and then lower it slightly.
DB_1361.jpg
Set the fence so the blade intersects precisely with the tongue cuts to form the shoulder. Repeat for the other side.

Box joints

Best uses: small boxes, drawers, chests, tool boxes

DB-0627.jpg
QR267_3boxjointsvid.jpg

A box joint provides lots of glue surface for a strong joint. Use contrasting wood species to add pizzazz to its otherwise purely functional appearance.

You can use a stacked-dado set, but a dedicated box-joint blade set [Sources] yields cleaner, square-cornered cuts. Install the blade set to the desired finger width. You'll build a simple, inexpensive jig (explained in the coming steps) that attaches to a regular miter gauge. When machining the fingers, cut them slightly long so they'll be about 164 " proud when assembled. (Blade height should equal the workpiece thickness plus 164 ".) Then you can trim the joints flush when assembled.

When cutting box joints, separate the box sides into opposing pairs. For the purpose of this article, we'll refer to them as sides and front/back. Cut these pairs identically to create symmetrical joints.

To get started, cut a test side and a test front/back equal in thickness and width to the actual box parts. Then follow these steps to make the box-joint jig.

Tip!

Rather than trying to cut boards to the precise width needed for a specific set of box joints, leave the boards a little wider than you think you'll need. You'll end up with a partial finger/notch on each, but you can quickly rip the boards to width before assembly.

Once you have a good fit, secure the plywood to the miter gauge with screws (or double-faced tape), cut both ends of the box sides in the first manner, then cut the front and back in the second manner. Glue the box together, clamp, and allow to dry. Trim the proud fingers with a block plane or flush-trim router bit.

DB_0604.jpg
DP-1642 copy.jpg
DB-0606.jpg
DB_0608.jpg
Fit the just-cut notch onto the spacer and cut another notch. Continue this step-and-repeat cutting across the width of the board.
DB-0613.jpg
Place the test side's first-cut notch onto the spacer and butt a front/back test piece against its edge. Hold both pieces tight and cut a notch in the test front/back.
DB_0618.jpg
Slide the test front/back's notch over the spacer and cut another notch. Then step-and-repeat across its width. Test the fit of the joint: It should slide together by hand using moderate strength. If you have to use a mallet, the fit is too tight.
DB-0626.jpg

Splined miters

Best uses: small boxes, picture/mirror/door frames

DB_0630.jpg
Install a rip blade and set its height to prevent cutting through the inside of the box. The deeper the cut, the longer the spline will appear on the outside of the box.
DB_1446.jpg

Miter joints look nice because they hide end grain, but they lack strength because glue doesn't bond well to the quartered end grain. Adding splines across a miter increases its strength substantially. (Cut spline slots with the blade at 90° as shown, or tilt the blade 5–7° for more pizzazz and strength.)

DB_0656.jpg
Avoid glue squeeze-out inside a mitered box by applying glue to only the outer two-thirds of the miter.

Tip!

For perfectly square-cornered spline slots, use a rip blade, which has flat-tipped teeth. A blade with alternate-bevel tips will leave tiny "bat ears" in the corners that a spline won't fill.

To cut the slots, you'll need to build a rip-fence saddle jig, shown below, to cradle the mitered box. Your jig should slide back and forth easily on the fence but without side-to-side slop. But before tackling the splines, you'll need to build your mitered box and sand it smooth.

100599737.jpg
DB_0631.jpgHold the box in the saddle jig, and slide it along the fence to cut a slot. Lift the box from the jig before sliding the jig back across the blade. Repeat for all corners.
Hold the box in the saddle jig, and slide it along the fence to cut a slot. Lift the box from the jig before sliding the jig back across the blade. Repeat for all corners.
DB_0632.jpg
For symmetrical splines, flip the box and cut slots in all corners again without moving the rip fence. To cut additional slots, reposition the rip fence as needed.
DB_0721.jpg
Cut splines from a blank at least 10" long. Use a thin-strip ripping jig [Sources or woodmagazine.com/thinrip] to set the spline thickness. Reposition the fence each time to rip another strip.
DB_0723.jpg
Test the spline fit in the slots until snug, and then cut short splines for each slot. Glue them in place, and trim flush when dry.

Add support with deep splines

For an integrated tray support in a splined-miter box, cut the center slots deep enough to penetrate the inside of the box at least 14 ". You'll need to make wider splines for this, but they will provide an almost-hidden built-in support.

34826.jpg
34830.jpg

Sources:
Matchfit dovetail clamps (2-pack), MicroJig, 855-747-7233, microjig.com. 8" box-joint blade set (14 " and 38 "), no. FJ08242, Forrest Saw Blades, 800-733-7111, forrestblades.com. Thin-strip ripping jig, no. 36833, Rockler Woodworking & Hardware, 800-279-4441, rockler.com.