- PLANS & PROJECTS
- Hand Tool Skills
- Box Joints
- Butt Joints
- Dovetail Joints
- Frame & Panel
- Lap Joints
- Miter Joints
- Mortise & Tenon Joints
- Pocket-hole Joinery
- Rabbets, Dadoes & Grooves
- Making Furniture
- Assembly & Glue-Up
- Fixing Mistakes
- Blades, Bits & Accessories
- Drill Bits
- Router Bits
- Tablesaw Blades
- Hand Tools
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How to Choose the Right Joint for the Job
By Mario Rodriguez
For a beginner, one of the most daunting aspects of building a piece of furniture is deciding what joints to use. Choosing the wrong joint can complicate construction, conflict with the design, undermine its integrity, and maybe even cause premature failure of a piece. A good place to begin when faced with the task of choosing a joint for a certain application is to identify and study the most widely used joints; there literally are hundreds of them in various configurations. Then consider the joints traditionally used in a particular type of furniture and evaluate your ability to execute them. Traditional joints all have withstood the test of time-we know they work. In this article I highlight some of the most standard joints and their common applications. They all can be executed by hand or by machine.
A butt joint simply is where the long-grain edges of two pieces meet to form a seam. It is used to increase the overall width of a panel. The strength of this joint relies on the straightness of the edges (not necessarily the squareness). With modern adhesives, this joint can work very well and be as strong as the
wood itself. When a butt joint is used to join the end of a board to the face of
another board, glue alone isn't sufficient; biscuits or dowels are necessary to add strength. One advantage of the butt joint is speed.
Another simple joint is the rabbet, in which boards are joined by removing a
portion of one board's thickness to accommodate another board. A rabbet
joint often is employed to set back boards onto the rear of a case piece. The back boards sit flush with the back of the case in the rabbet. Sometimes on simple cabinets the drawer sides are joined to a drawer face with a rabbet
joint and nails.
Another joint that is easy to make, attractive, and functional is the dado. Put simply, a dado is cut across the grain of one board to receive the end of another board. It's great for locating partitions inside cabinets or for supporting shelves on bookcase units. It can be cut across the full width or stopped.
A plow is similar to a dado, except it runs in the same direction as the grain. You
can use it in the construction of frame-and-panel doors and for setting in drawer bottoms.
If you were building a cabinet or sideboard with a face frame that intersects at various points, you might use a half-lap joint. On this joint you remove the full width of each intersecting member but only half of the thickness. Several half-lap joints on a cabinet face frame will ensure that it is rigid and long-lasting.
Tongue-and-groove joints provide a mechanical means of registering and joining the edges of narrow boards when forming a wider panel. Along one edge
of a board a tongue is cut, usually centered on the thickness of the material.
On the other board, a corresponding groove is cut. One advantage is that the edges are registered, requiring little planing or cleaning up. This is particularly helpful when gluing up long boards without the aid of cauls to keep them flat. Another advantage is the increased glue surface. Disadvantages are that the joint is visible from the end of the panel and the joint requires precise milling to ensure that all parts fit correctly.
The finger joint, sometimes called a box joint, interlocks two boards at a corner similar to a dovetail. However, instead of angled tails and pins like on the dovetail, the fingers are straight. This joint has a clean, utilitarian look that makes it perfect for kitchen, office, or shop containers. In my shop, I have
several small toolboxes put together with finger joints.
Anyone who has ogled a painting or stared into a mirror is familiar with the miter. This joint is used on small boxes and decorative frames of all kinds. The first hurdle is to cut each half of the joint to 45 degrees; then you have to figure out a way to glue them together without one half slipping past the other. The neatest way to align a miter is with a spline set into a slot cut on each side of the miter. The spline, in some cases, also provides a nice accent.
One of the most basic and widely used joints in furniture making is the mortise-and-tenon. This joint can be used to join the rails and stiles on frame-and-panel doors, the aprons to the legs of tables, and the rails to the posts or legs of chairs. Because of the deep penetration of the tenon into the mortise, wood parts can be supported securely, even without the benefit of glue. There are many variations to the mortise-and-tenon. The tenon can be stopped or continue through a board, and it can be reinforced with pins or wedges.
Considered one of the strongest and certainly the most beautiful of joints, the dovetail exacts a stiff price in terms of skill for the strength and good looks it provides. This is probably the strongest method for joining two pieces with the
grain going in the same direction. There are baSically two types: through and halfblind. Through-dovetails are used to join carcases, blanket chests, and small boxes. Half-blind dovetails are most commonly used to join drawer sides to drawer fronts, but occasionally you'll find the joint employed in the construction of carcases. Today, there are jigs that enable a woodworker to cut dovetails by machine, but the end result looks mass-produced. The best-looking dovetails always have been cut by hand.
Sliding dovetail joint
This joint consists of a dovetail-shaped tenon that slides into a corresponding groove or plow. It can be used like a dado for supporting shelves on a bookcase while offering extra strength to keep the sides of the bookcase from bowing outward. If you were building a Shaker candle stand, the sliding dovetail would be the strongest way to attach the legs to the column. In this instance, the dovetail-shaped joint keeps the legs tightly attached to the column.
Keep it simple-- Sometimes the simplest joint can do the job . There's no
need to complicate things, and sometimes overdoing It can be detrimental. For instance, you don't have to pin every mortise-and-tenon Joint; glue usually is sufficient to ensure a strong bond.
Stick with what has worked historically--In woodworking, there's often a good reason why things have been done a particular way for hundreds of years. Woodworkers sometimes struggle to reinvent a joint by exaggerating
a part of it. For instance, when cutting dovetails, more is not necessarily better. Crowding the joint with pins can leave too little material on the tail board to support the joint. Study well-regarded pieces to follow as examples. The surest way to build successful furniture is to copy what has worked.
Make sure it fits properly--If you've bothered to make it, then make sure it fits well. Sloppy joints will come apart prematurely when the glue fails. Take your time, test-fit your pieces, and replace anything that's loose or cracked.
Make sure the work is clean--I have one paramount rule regarding anything I build: Every piece should represent the best I was capable of building at the time. You shouldn't look at your work and think you could have done better. Sloppy work and shortcuts will haunt and trouble you forever.
Show off the joint if it's appropriate--Nothing looks better than eye-popping dovetails or a tight, pinned mortise-and-tenon. When the Joint fits the style of
the piece, show It off.
Four Criteria for Choosing a Joint
1. The joint should contribute to the strength and Integrity of the piece.
2. The joint should allow the wood to move as ambient conditions change.
3. The joint must allow for additional operations, such as grooving, rabbeting, moldings, or screws.
4. The joint should contribute to and not interfere with the appearance of the piece.
Drawings by Mario Rodriguez
This article originally appeared in the November/ December 2003 issue of Fine Woodworking.