What’s the difference between a dado, a rabbet and a groove? It sounds like the start to a convoluted joke, but really, it’s a topic that bears discussing. Beyond the butt joint, these types of cuts form the simplest joints possible in woodworking. They’re traditional, they’re easy and they’re all fairly similar — with slight differences. Mastering these three types of cuts allows you versatility in your routing without much variation in technique, allowing you to join nearly anything your heart desires.
What’s a Groove?
A groove is a square or rectangular slot that runs parallel to the grain of the wood. Drawer bottoms are a great example of where to find a groove. Grooves can run the full width of a board, can stop at one end or can be stopped at both ends of the project — the last of which is also called a mortise.
Typical grooves are cut approximately a third of the thickness of the board, no more. Any deeper, and you run the risk of not having enough support under the joint to hold whatever’s going above it — imagine a weak bookshelf collapsing or a drawer that can’t even hold a sweater. The width of a groove is about the same as the material housed in the slot — so for a bookshelf bottom that’s joined with a groove, you’d make the width of it as wide as the sides of the bookshelf.
What’s a Dado?
A dado is similar to a groove, but instead of running parallel to the grain of the wood, it runs perpendicular or across the grain. Like grooves, dados can run the full length, stop at one end or be stopped at both ends — it’s still called a mortise when a dado cut is used.
Dados follow similar load bearing rules as grooves — no deeper cut than a third of the thickness of the board or you’ll risk a weak project that can’t bear weight. The width of a dado groove should follow the same rules as that for groove slots — the same as the material housed in it.
What’s a Rabbet?
Rabbets are two sided notches cut into the edge or at the end of a board. They can be cut with or across the grain and the sides form a 90 degree angle to one another. These simple cuts allow you to fit two pieces together where strength isn’t critical — a cabinet corner, for example, or to hide the back of a bookshelf or cabinet.
Size is cut with the board that it receives in mind. The width of the back of a cabinet, for example, determines how deep of a rabbet on the side of a cabinet.
Cutting Rabbets, Dados and Grooves
Routing creates a uniform cut across a project or across a run of projects. When you’re routing and creating rabbets, dados and grooves, they’ll be somewhat standardized. There’s a number of ways to achieve rabbets, dados and grooves on routers. Jigs are an asset for dados and grooves – a T-square jig, for example, enables you to cut grooves and dados with ease. Router bits for creating rabbets exist and can be used to achieve a uniform result across a project. With a rabbet bit, you can create different sized rabbets by attaching different bearings to it.
What’s your favorite among the three: rabbet, dado or groove? Why?