Not the showiest or most complex of woodworking joints, rabbets, dadoes and grooves are, nonetheless, three of the most practical and versatile joints you'll ever cut. Best suited to cabinet and furniture carcass construction using plywood, MDF and similar sheet goods, all three joints are also good for some solid-wood applications, such as building simple boxes and drawers.

Overlap rabbet

Whatever an overlapping rabbet lacks in strength is more than made up for by how easy it is to make: A tongue cut on the end or edge of one part laps over the mating part (Photo 1).  Only one part is cut, so each joint is quickly made. Overlap rabbets are great for joining drawer boxes, as the end grain of the sides won't show on the assembled drawer (a separate front piece covers up the front of the drawer, and the rear is only seen when the drawer is removed).

The proportions of this rabbet joint depend on both the thickness of the workpieces and the application of the joint. For example, if you're using an overlap rabbet to join the corners of a drawer or box, the tongue should be cut about half to a third as thick as the drawer/box side, and the same length as the thickness of the mating part. When cut from plywood, the resulting joint can be simply glued together, forming a serviceable drawer or box. If the joint is cut in solid wood, it's best to add dowels or other reinforcements to the joint, as side-to-end-grain gluing produces very little strength (Photo 2)

In addition to building boxes and drawers, an overlap rabbet is also great for creating a recess on the inside edges of a picture frame for the glass and backing, or for attaching a cabinet back (Photo 3).  The tongue cut on the inside edge of the cabinet parts houses the cabinet back and not only creates a mechanical connection that keeps the assembled cabinet from racking, but also hides the unsightly edge of a plywood or veneered MDF back panel. In this application, cut the tongue about half the thickness of the cabinet sides and at least as long as the back is thick. For example, for a cabinet built from 3/4 in. plywood with a 1/4 in. back, the tongue would be about 3/8 in. thick and at least 1/4 in. long. If the cabinet is to be "scribed" to the wall when installed (the back edges trimmed to conform to an uneven wall or tile surface) then the tongue should extend at least 1/2 in. or more beyond the back.

Double rabbet

This joint interlocks the ends (or edges) of the mating parts with identical rabbets cut on the ends of both parts (Photo 4). A double rabbet forms a mechanical joint with more surface area than a simpler overlap rabbet, which makes for better gluing strength, especially when plywood is used. Although they aren't commonly seen in furniture or cabinet construction, double rabbets are reasonably attractive and strong and could be used in all manner of carcass, chest, box, drawer and tray construction. The mating parts of each joint must both be cut, but the rabbet on each is identical, so that setup time is minimal. You can also use double rabbets to join the sides of a chest or box made from solid wood, and the joints help keep parts aligned during glue-up (Photo 5).  If the chest/box will see heavy use, it's prudent to reinforce the corners with dowels, dovetail keys or other means.

Blind rabbet

Sometimes called a dado rabbet, a blind rabbet joint requires a rabbet cut in the end of one part that fits into a dado cut on the other part (Photo 6).  This configuration does add some mechanical strength to the joint and makes glue-up easier, as parts positively lock into each other and don't slide around. However, when used with solid wood parts, the short grain lip formed outboard of the dado is prone to breaking off. For better strength, it's best to cut the dado a short distance from the end. This joint is often used to join the back of drawers to the sides.

Cutting rabbets

Overlap, double and blind rabbet joints can be cut with hand tools, including the eponymous rabbet plane. But most woodworkers will find these joints a lot easier to cut with a tablesaw or router. For table saw rabbets, you have a choice: use a regular blade and cut the tongues required for any of the three rabbet joint variations in two passes, or mount a dado blade and cut each tongue in a single pass.

For the regular saw blade method, the first cut passes the piece vertically over the blade (a limitation if you have long workpieces). I make this cut using a sliding carriage that's guided by the rip fence (Photo 7).  Alternatively, you can use a commercially made tenoning jig that slides in the saw's miter slot. Set the blade's depth of cut to the desired tongue length, and the jig's side-to-side position to yield the desired tongue thickness. Next, use the saw's sliding miter gauge to cut the shoulder of the joint with the stock laying flat on the saw table (Photo 8).  Reset the blade height to match the height of the tongue's shoulder, so that this cut meets with the previous cut. To assure consistent tongue length on multiple workpieces, you can use a miter gauge with a fence and stop system, or set up a stop on the saw table. Just make sure the stop doesn't trap the scrap that's cut off, as the blade can snag the scrap and launch it dangerously back at you.

The dado method (Photo 9) requires you to swap your regular saw blade for a dado set, but it can save you time as rabbet tongue is cut in only one pass. First, mount a dado stack that's slightly wider than the desired tongue length. Next, clamp an auxiliary face (a strip of scrap MDF or plywood) to your rip fence and set it so it overlaps the dado blade. Now slowly raise the spinning blade into the face (not the fence itself!) until it's high enough to create the desired tongue in your stock. Now reposition the rip fence to expose the right amount of dado blade to make the desired width of the tongue.

Router rabbets

While the table saw provides a relatively quick way to cut a slew of rabbet joints, the router is also a powerful tool for cutting this joint. There are a couple of ways to use a router for rabbetting: One way is to fit the router with a straight bit and mount it in a router table, and cut rabbets in the same way as with the dado table saw method described above. But an even easier method uses a rabbet bit in a freehand router (Photo 10).  A rabbet bit has a bottom-mounted guide bearing that limits the width of the stepped cut the bit takes. With the stock lying flat on the benchtop, the router's depth of cut determines the thickness of the rabbet's tongue, while the bearing size determines its length. You can change tongue length by fitting a different sized guide bearing (Photo 11): Smaller bearings produce a longer tongue; larger ones, a shorter tongue.

When cutting through rabbets on parts such as drawer sides, it's a good idea to clamp scrap blocks on both sides of the part, with their ends flush to the part. This keeps the bearing running straight at the beginning and end of the cut, for a perfect joint every time.

You can also use a router and rabbet bit to form rabbets on the edge of a workpiece, for example, to create a recess for the top or bottom of a box or chest. In this orientation, guide bearing diameter determines tongue thickness and the bit's depth of cut sets tongue length. When routing narrow parts, clamping a scrap strip to the workpiece (as shown in Photo 12) creates a wider edge that helps prevent the router from tipping as you work.

In addition to routing regular through rabbets, rabbet bits provide an ideal way to cut stopped rabbets - where the joint stops short of the end or edges of the parts. With the box shown in the last photo, the rabbetted recess doesn't show on the outside surfaces of the box. However, the bit leaves rounded corners that must be squared up with a chisel if a square bottom or lid is fitted (Photo 13).  Alternately, you can leave the rounded corners alone and radius the corners of the lid or bottom instead.

Dado joints

Cut a groove across the width of a part - a cabinet bottom, drawer side, blanket chest top - and fit another part into the groove and you've created a dado joint. Dadoes are the preferred joints for creating quick, yet strong connections when joining shelves to the sides of a bookcase, bulkheads in a kitchen cabinet or dividers in a chest or drawer. Dadoes are also a handy joint to use when building a rack or open cabinet cubbies, for tools or supplies, or bins for small parts and fasteners (Photo 14).

Creating a dado joint is easy: You can cut the cross-grain (or cross-panel) groove with hand tools (rabbet or plow plane, handsaw & chisel, etc.), with a dado blade in a table saw (the blade's name is a pretty good clue here) or with a straight bit in a router. The table saw is particularly well suited to making through dadoes, where the groove is cut across the full width of the stock (Photo 15). You can use the saw's rip fence to guide wide workpieces for the cut, or use the miter gauge for narrow ones. The dado groove is typically cut to only about 1/3 as deep as the thickness of the workpiece. This keeps the groove from weakening the part. The width of the dado groove corresponds to the thickness of the mating part, so you must adjust the width of the dado stack to create a snug fit. A fine-tuned dado stack is necessary if you're working with sheet goods - plywoods, particle board, etc., that aren't a standard dimension (1/2 in., 3/4 in., etc.). For router-cut dadoes, you can buy special plywood bits that are available in diameters that match true plywood thicknesses: 15/64", 31/64" and 23/32" (Photo 16).

An alternative to fooling around with dado stacks and special router bits is to cut your dadoes to a standard width that's slightly less than the thickness of the mating stock and cut a shoulder on the ends of the mating piece (Photo 17).  This creates what's known as a "shouldered dado" joint, which is very similar to the blind rabbet joint discussed earlier. You can cut the shoulder with either a rabbet router bit (see above) or with a dado blade in the table saw (Photo 18).

Through dadoes are easy to cut, but you don't always want the joint to show at the edges of the assembly. A stopped dado doesn't go all the way through to one (or both) edges of the stock and thus creates a cleaner look more suitable for contemporary style cabinetry and furniture. A router is the perfect tool for cutting stopped dadoes. After chucking a straight bit into the router that's the diameter of the desired dado width, set the router's depth of cut to make the dado as deep as desired. With the workpiece clamped down to the benchtop, clamp a straight wood strip atop the work, to act as a fence that guides the base of the router. Also clamp a block to the bench to stop the router bit's travel short of the edge of the work. (Photo 19). Square up the stopped end of the router cut with a chisel, and trim the front-facing edge of the mating stock to fit the trimmed end of the dado. (Photo 20).

Grooves

Unlike dadoes cut across the grain of the wood (or width of a panel), grooves are cut with the wood's grain (or along the length of a panel). When cut into the face of a part, a groove is useful for securely capturing a cabinet's back panel or the bottom of a chest, box or drawer (Photo 21).  But you can also cut a groove to, say, hold a raised panel in a door or mirror in a frame (Photo 22).  You can also use a groove to create a spline joint to reinforce other joints (miters, butt joints, etc.), or as half of a tongue and groove joint used to connect paneling boards, flooring and more.

You can cut grooves using any of the same methods described for cutting dadoes. If grooves are cut "through" instead of stopped (see dado section, above), I prefer to use a table saw fitted with a dado blade set to the desired groove width. When cutting narrow grooves for thin sheet goods, you can use a regular saw blade and make the cut in two passes, repositioning the rip fence in between cuts (Photo 23).