How many corner joint methods are there? How many have you built? What’s your favorite one, your go-to choice when building something in your woodworking shop?
There are many ways to join two pieces of wood together, and the method of joinery you choose depends often on the project. A picture frame, for instance, is likely to have mitered corners.
But what about a bureau or chest of drawers for your bedroom? Or a jewelry box? The strength and durability of those corner joints is important for structural integrity, and a mitered corner just wouldn’t do.
What Are Common Corner Joints?
There are many corner joinery methods used in woodworking, and to some extent, the ones you choose for your projects have to do with your skill set and woodworking experience. Some choices also are dictated by the project itself – how much weight will the joint support or what use the workpiece will be put to that might strain the joints.
Among the common corner joints:
Mortise and tenon joint
It’s been used for thousands of years to join two pieces of wood together at a 90-degree angle (a corner). A mortise hole is cut into one piece of the wood, and a tenon tongue on the other is glued and inserted into the mortise. Many consider it to be the strongest joint in woodworking.
It’s a flush-fitting joint that uses the strength of the wood itself, the tongue (tenon) inserted into the hole (mortise), and lots of surface for glue to grab hold tightly. It’s a simple design, and with good workmanship, it is aesthetically pleasing to the eye.
In today’s woodworking shop, we have the Festool Domino, a tool perfectly designed for a “mortise and tenon” joint that has removed the need to cut a tenon. The tool creates a mortise with a single plunge in each of the two pieces of wood being joined, and dominoes (ridged pieces of wood that fit within the mortise) are glued up and used to join the two pieces of wood tightly.
A groove or dado is cut on one end of pieces of wood to create a “lip.” These lips are then glued up and joined to form a 90-degree angle. It’s a simple design, and with the right power tools is easy to construct. The dado blade can do all of the work for you on your table saw to create the lip(s) in your workpieces, and glue does the rest. Perhaps for extra strength, a brad or two into the joint can enhance durability, too.
It is considered a strong joint.
Dovetail joints have trapezoidal profile cuts that are slid together to join two pieces of wood at a 90-degree angle. The profile cuts give the appearance of a dove’s tail, and thus the name for the joint. They are very common in furniture-making and are considered to be very strong joints, and some consider it to be the strongest.
Dovetail joints require very precise cuts in the wood with a handsaw and chisel. If they are poorly made, the joint will be weak and eventually fail. They do not require mechanical fasteners to strengthen them like other joinery methods do. They use the pin-and-tail interlocking dynamic where the pin of one piece locks into the tail of the other and, with a little glue, hold tightly and snugly to each other. So, no nails or screws are needed.
The dovetail joint, though, is among the most difficult joints to make. Again, precision cuts are essential to create the strong joining of the work pieces. You can cut dovetails with a router and a dovetail jig, but for smaller pins, you will need hand tools. Saws, chisels, and knives are the common hand tools used to create dovetails.
Japanese hand saws are particularly good for this job; the dozuki is a great hand saw to have handy for this task. A coping saw might come in handy, also, to remove any wood waste from the cuts, and then follow that with a sharp chisel to smooth out the cut.
It may sound difficult, but once you’ve cut one or two dovetails, you realize it’s just a saw cut and chisel cleaning, and in that sense is a little different from other cuts and chisel cleaning tasks you’ve done on other projects.
We’ve written about dovetail joints in the past, and you’ll find one of those pieces here.
This is a basic joinery method to create 90-degree corners with some strength. Offset profiles are cut in two pieces of wood, and the “pins” thus created are then slid and interlocked together. They are cut straight and parallel, so sliding them together is simply a matter of lining the two pieces up to each other and sliding them directly into each other.
Box joints are, often referred to as finger joints, are a cousin of the dovetail in that two pieces of wood are interlocked to form a corner. Instead of the angled pins and tails, though, the box joint uses straight cuts to form the pins that then interlock with the cuts in the second piece of wood.
The number of pin cuts in each work piece will determine the total surface area that is available for gluing. The more gluing surface, the stronger the joint will be.
This distinguishes box joints from dovetail joints in that the pins and tails of the dovetail are angled and grip each other once joined. They can be interlocked in only one way (the joining way) and can not be pulled apart as the angles work against each other to form that tight grip. The box joint, on the other hand, is made of straight pins and cuts; they can be interlocked from any direction as the two pieces of wood are joined.
These joints are the easiest, quickest, and weakest of the joints. Two pieces of wood are simply joined at a 90-degree angle without any special shaping or cutting as in the mortise and tenon, rabbet, dovetail, or box joints. The pieces are joined at right angles end-to-end, and the joint is usually reinforced. This is because, on its own, the joint is not especially strong.
Are Dovetail Joints Stronger Than Box Joints?
The answer to this question depends on who you ask. In woodworking, we all have our favorite ways to join wood in our projects. Some depend on our level of experience; some are simply a preference.
Most will argue that the dovetail joint is inherently stronger than a box joint because the pins and tails are angled, making them difficult to pull apart. The pulling pressure puts the angles against each other in energy, and if the cuts are precision-made, that pull is hard to break the joint.
In box joints, the pins and cuts are straight, and sliding them in and out of each other is multi-directional, rather than the single way a dovetail joint can be interlocked.
This is another point on which woodworkers disagree. Some argue that the straight-cut pins of a box joint workpiece will provide a greater gluing surface, resulting in a stronger joint.
Others will argue that it depends on the number of pins and tails cut in a dovetail joint. The more pins and tails, the greater the gluing surface, as the argument goes.
The through dovetail will have a greater angle and thus a greater gluing surface; the half-blind dovetail will have even more due to having 4 surfaces rather than the 3 of a through joint.
However, with regard to box joints, the number of fingers can be greater because the cuts are straight rather than angular and can offer better proportional measurements on smaller projects like a jewelry box.
In other words, glue surface is a lesser argument to support a contention that a joint is stronger than another joint.
Uses of Box Joints and Dovetail Joints
While box joints are quite common due to their ease of cutting, dovetail joints are held onto tightly by old-school woodworkers and high-end furniture makers.
Each is suitable for:
- Cabinet carcasses, bookshelf carcasses, and chests of drawers
- General box construction
Many times, it comes down to appearance. The dovetail joint, especially when joining two different types of woods with different color profiles, is quite beautiful and classy. It is also a sign of great care, having been shown to the joinery, the cutting, and chiseling to create the tight fit of the pins and tails.
This is not to say a well-formed box joint is ugly. Again, the joining of two different types of woods with different color profiles in a box joint can also be quite handsome. The degree of difficulty to create it, though, is less than that of a dovetail joint.
Although it’s a video from 2012, the dovetail joint hasn’t changed since then or even over the centuries during which it’s been used. It shows how to make a dovetail box in only 12 minutes.
For tips on making box joints, we offer this video with some helpful ideas.
Each joinery method creates an aesthetically pleasing corner in your box, drawer, or carcass. Make a dovetail joint at least once in your woodworking career, and use hand tools to make it. The box joint is more easily made, and power tools are the best choice for them.
Then make up your own mind as between the two – for ease, for appearance, and for strength.