Good woodworking features many different kinds of joints, but one of the most broadly useful is the finger joint. This is a method of joining two pieces of wood together using matching rectangular cuts and glue. It’s also called a “box,” “comb,” or “box-pin” joint.
To get an idea of what a proper finger joint looks like, bring your hands together at right angles to each other with your fingers open and interlaced. This should make it clear why it’s called a finger joint! Finger jointing makes a stronger connection than an ordinary lap or butt joint, and a well-crafted finger joint adds aesthetic appeal to the work.
Good workmanship and accurate cutting are essential for a proper finger joint. The goal is to craft a set of “fingers” on each piece that come together seamlessly, free of gaps. Adding glue to the joint creates a very tough, permanent bond. Some of the woodworking tasks that regularly call for box joints are cabinetry, cupboard building, and making delicate furnishings like jewellery boxes.
The history of the finger joint stretches back for decades, but they are becoming more popular than ever lately. This is likely due to a sad decrease in the quality of of woodworking materials and an increased appreciation for fine craftsmanship. Building a proper joint that will stand up to plenty of punishment requires precision, properly-cured wood, and carefully controlled application of glue.
From a carpenter’s point of view, the main advantages of using a finger joint is that it keeps lumber straight and offers terrific dimensional stability. Shorter pieces of wood can be knit together into larger, longer beams with finger jointing. This process avoids the twisting, racking, and warping that’s all too common with large-dimension lumber. A skilled woodworker can even excise lumber defects using finger joints to produce a composite piece with greater strength and load-bearing capacity.
In summary, these are the main advantages of finger joints:
Pieces which have been joined with finger joints are at least as strong as dimensional lumber, if not stronger.
Bows, crooks, and other directional irregularities are eliminated in the finger jointing process.
Lumber that has been finger jointed is less susceptible to twisting and warping.
Studs that have been finger jointed are easier to nail because their edges don’t display wane (dimensional inconsistencies).
Finger-jointed wood displays fewer unpleasant defects like discoloration and wane.
Finger joints are carefully evaluated to confirm that strength, water resistance, and appearance all meet the highest standards.
Reduced Ecological Impact
Using finger joints is a great way to make use of small pieces of high quality wood that might otherwise turn into waste. This means more utility is derived from each tree that’s turned into lumber.
Here is a quick video from Steve Ramsey on how to make easy finger joints without any special tools. Enjoy!