In a recent post, I talked about four simple woodworking joints . Here I am going to go into some more complicated joinery, starting with locked joints, where the wood itself makes up part of the strength of the joint.
Photos via wooden-box-maker.com
The most famous locked joint is the dovetail. They are elegant and strong and are great for joining corners in solid wood. Because of the way the pins and tails are formed, the joint “locks” in one direction, but not the other. The pins can pull clear of the tails but not the other way around. You can see in the photo which way the strength goes. You can pull the vertical board out but not down. It’s good to keep the orientation in mind when deciding which board gets the tails and pins.
Dovetails are considered the hallmark of fine woodworking, especially hand-cut dovetails . They are used in fine woodworking, and also in production (especially drawers). The main disadvantage to dovetails is that they are difficult and time consuming to make.
A box joint is another strong and nice-looking joint. It is used in the same manner as dovetails, although it doesn’t have the same reputation.
Making them requires a precise jig that can be fussy to set up. Once you have the jig, you can make a consistent, strong joint.
Locking joints can also be made with a router or table saw, creating interlocking pieces that will hold together in various ways. Dedicated router bits can make the joints for you, or you can set up various combinations of straight bits to make your own.
Mortise and tenon
Mortise and tenon joinery works well for joining wood where the grain of the abutting woods are perpendicular to one another. A mortise on one board is fit into a tenon on the other. It is often used to attach table legs to an apron and with doors to make the stiles and rails. It is also the joint for making “bread board ends” on table tops. Make sure you leave room for wood movement when cutting mortise and tenons.
A half lap is great for joining thin stock, especially in the middle of two pieces of wood. I often use it for drawer dividers . It can also be used to join two pieces of wood along the same grain direction. If you need to “lengthen” a board, for instance.
A dado is a simple groove cut in the center of a board so that another piece of wood can sit within it. To make it stronger a stub tenon can be cut, or stronger still, use a sliding dovetail. Pay attention to wood movement when gluing a board into a dado.
Variations on a theme
For each of these joints you can rearrange them to suit your specific purpose. For example: round over box joints and then drill through them to create a hinge.
Use "faux dovetails" instead of splines to strengthen your miters .
Use a sliding dovetail as your tenon for super strong joint.
Mix several types of joinery to make a complicated joint. The example below has miters, a locked joint and a dado.
It's fun to make up your own. After all, if it holds the wood together it's a good woodworking joint.