I’m going to dive right in here and assume you have no idea what I’m talking about, yet. If you are an experienced woodworker, you really have no use for my blog, other than to correct careless errors in my work (which is all good, just please be tactful! haha). This blog is meant to provide a one-stop-shop for rookies and green-horns who are trying to find the same answers that I did over the past few years. I try to give situation-based challenges and provide all the relevant information that I need to help solve the problem. Sometimes it’s really harder than it needs to be to find a simple answer, like lighting theory for example, such a pain to get actual relevant information and solid “theory” about the topic of lighting from which to build a solution in my head. I want to spare you that frustration. To that end, I bring you a primer on joinery, with a little inspiration from our friends over at Wikipedia.
I often associate carpentry with framing work, like building houses, sheds or garages. You use hammers, nails and don’t need all of your work to be skin-friction-tight. If you under-cut a board by a 1/16th of an inch, you don’t necessarily discard the piece and grab a new length of lumber. In woodworking, you often have no choice. Many or most of the woodworking projects that I can imagine can be completed without any metal fasteners at all, though I don’t always recommend this. That said, depending how you go about it, classical/traditional joinery is often so much better/stronger/cleaner/cooler than screws that it’s hard to imagine. Let’s dive in.
Without any particular rhyme or reason to my order, I’m going to discuss about twenty different types, in small categories to make it easiest to associate them without complex/compound tables and that’s just the basic array. You could spend a lifetime exploring cultural practices like Japanese joinery, or the category of log cabin work. I will be discussing 5 distinct categories that helped me learn the techniques: Simple Joinery, Integrated Joinery, Metal Fasteners, Wooden Fasteners and Chemical Fasteners.
When you lodge one board next to another, with end-grain against long-grain (left), you are butt-jointing. To fasten boards long-grain to long-grain you are edge-jointing. To join two boards at an angle, that requires (often equally) angled cuts, you are making a mitre, hence mitre saw, and if you can fasten two short end-to-end to make a longer board. You can do compound stuff, but I don’t want either of our heads to hurt today.
These can be done using mechanical fasteners, or an integral fastener such as dowels, pocket holes, splines, biscuits, dominos, glue, epoxy, mortise and tenons, etc, described later in this article. This has more to do with wood placement than HOW it is joined together. However you connect the wood together, it’ll probably either be either one of these three methods. Each has it’s advantages and disadvantages, and you don’t always have an option between any of the three for a given situation. I’ll explain…
Dovetail, Box-joint, Bridal Joint, Half-Lap, Butterfly Joint, Dado, Rabbet, Mortise and Tenon
Let’s go from top left, to top right, and straight to the bottom. Number one is a Butt-Joint, just one piece butted against another. Fast, dirty, but terribly weak if adhesive (wood glue, epoxy, etc) is used or if fasteners (wooden or metal) are selected. Not even remotely fun to make.
Then you have a Bridal Joint in the upper right; think of the wood holding hands. By cutting a “rabbet” in the wood, you are both increasing the surface area of the wood and functionally eliminating edge-grain from the joint, which will make it much weaker. This is a very strong joint, but you are reducing the overall width of the board where you slimmed them down for the joint to match the thickness of the original boards, and will be a weak spot.
Next is what some people call a Rabbet Joint. Rabbet comes from the french word for Rebate, or to take/give back. You pare away some wood on ONE side of the joint equal to the thickness of the wood not modified. It’s a half-way measure between Bridal and Butt.
Next is my favorite, the Dovetail Joint. It’s just a work of art. By cutting a tail (the fan-shaped piece) and two pins, you are effectively making a wedge that resists being drawn out in one direction, and can be removed by pulling in the opposite direction. Fantastic for nearly all applications, but requires the most skill to complete and requires some planning when assembling the joint. You wouldn’t want it to be in a drawer and the drawer-face be the board with the tails, it’ll just pull apart. Cut pins into the front and back of your drawer and the more you pull, the tighter the joint becomes
Not sure why number 5 is also a butt-joint, but I’ll show you a box-joint (right) in it’s place. Box Joints are lovely and crazy-strong. They are like many bridal joints made over and over again, and (typically) glued into place. Because of the nature of rotation, in order to pull the boards apart, the square teeth resist the moment (rotation-force) and the wood board usually breaks before the joint does.
Sixth type in the image above is the Mitre Joint, you’ve probably seen this little guy most often in picture frames. Quite easily reinforced using splines, biscuits, dominos or tenons, (all detailed later in Wooden Fasteners) they are most-often glued. Appropriate here, too, because I would never, ever perform one without something more complex to reinforce it, the contrast to other forms of joinery helps the logic along.
Bottom left is a Mortise and Tenon joint (a supplemental picture can be seen to the left). Frequently performed with a Butt-Joint, but a sufficiently skilled and creative craftsman can use this technique just about anywhere. (Floating Tenons to be discussed in Wooden Fasteners section) The idea, once again, is like a bridal joint and box joint, where you elongate part of the joint to increase gluing surface area. This is different from a box joint in that the tenon need not go all the way through the receiving piece with the Mortise (otherwise known as a through-tenon) and if it extends all the way to the end of the board, it becomes a different kind of joint entirely, a bridal.
Finally, the lower right corner of our collage is a Tongue and Groove Joint. Very common in commercially available products, like plywood or wallboard, it is like a very shallow bridal. One board’s tongue slides smoothly into the groove of another board and not only provides strength but also can function as a sliding method for drawers and other methods. T&G Joints, like several others above (Can you deduce which ones) also provide a great deal of strength for their alignment properties, to ensure that the boards don’t slop around when glued.
Screws & Nails
You can reinforce just about anything with screws or nails. Brackets can be useful in every case, but are more the real of carpenters who need a job done quickly. Unless you’re a Quaker, you probably aren’t going to be using complex or traditional joinery on larger projects or ones that you need done yesterday. These are often selected over more permanent alternatives such as glue or epoxy’d traditional joinery is if it needs to be disassembled. One very effective way to hide metal fasteners is with pocket holes. Though often used in butt-jointing, it can be functionally used anywhere, and wooden dowel “plugs” can be used to cover up unsightly holes. Kreg(r) makes the blue jig to the right, and are available in many places; click the link to see what Lee Valley offers. Definitely a fast-and-dirty solution to holding boards together, and pocket-hole screws have the advantage of gripping multiple layers of fibre at one time, where wood only relies on skin-adhesion, depending on it’s penetration. Nails are also an alternative, like pneumatic pin-nailers or hammer-driven finishing nails. They can be unsightly and can make sanding/planing a pain later on.
Dowels, Loose Tenons, Biscuits, Dominoes, Splines
So you’ve butted one board against the other, cut your box joints in the ends and interlocked. You now want a stronger form of joinery without using glue or epoxy (chemical fasteners, next section), why not use a dowel? Once it’s all said and done, fitted and sanded, shaped and conformed to a texture you like, drill a hole through the whole joint, top to bottom. Then run a wooden dowel through the whole thing, like a pin in a door hinge. Point-of-fact, if you loose-fit the box joint and round over one side on each of the boards, you can make a lovely hinge using this technique.
Dowels (often combined with chemical fasteners) can frequently replace metallic fasteners entirely, and make sanding/smoothing much simpler. I love these little guys and there are even techniques available to make your own quite simply and amazingly controlled thicknesses.
Loose tenons come in three basic types, one is simply called a Loose Tenon, another is Biscuits and a third is a Domino. Dowels are just cylindrical variations of this theme. Tenons are usually solid wood, long-grain oriented, with rounded edges (but not always) and parallel sides for easier preparation of the Mortise (the hole it fits into). All kinds of gadgets have been produced to make this job a little easier, and Matthius Wandel of WoodGears.ca is one of the kings of jigs, especially his hand-made slot mortiser. Biscuits and Dominoes, though there are varients, are mostly used to align boards, and lack the inherent strength of a tenon or a dowel. Each has their place, of course, and each will add strength to a joint, so it’s sometimes a matter of preference.
Now splines are one of my favorites, they are sort of the lovechild of floating/loose tenons and bridal joints. Frequently used to reinforce mitre joints, they are a sliver of wood you slide into a slot that is cut away all the way through to each side (like a dado) and is slid into place (like a loose-tenon) but extends right to the ends (like a bridal) and is glued into place. You could easily make this little guy more like a floating/loose tenon by not extending it right to the edge, and can go in either direction shone. Using contrasting woods can add a stunning appeal to a typically boring joint.
Yellow Wood Glue, Cyanoacrylate and Epoxy, among others
There are three types of chemical fasteners that are virtually indispensible for a woodworking shop, that’s conventional yellow wood glue (typically Titebond or some variant), Cyanoacrylate (superglue) and the solution of epoxy resin and hardener agents. I’m sure there are others, but I’m sure this is boring enough already.
Yellow Wood Glue strives for the synthetic equivalent of Lignin, which is the chemical bond that holds all the parallel wood fibres together to make cellulose wood fibre so strong and cohesive. When you properly apply yellow wood glue you are functionally replicating the original material that keeps wood so strong, and prevents it tumbling apart like a bundle of straws that falls from it’s container, or a tumbled bag of spaghetti noodles. One of the market leaders in this area is Titebond, and has three variants creatively named I, II, and III (generally considered regular indoor, water resistant indoor, and waterproof outdoor respectively). It’s good stuff and I feel naked in my shop without some around.
Cyanoacrylate, or CA glue, is best known for it’s capacity to stick your own fingers together better than anything else. It’s a simple adhesive frequently used as a first-aid supply for it’s ability to stick a wound together while being non-toxic, and hardens into a hard, plastic, resin coating very quickly. I’ve seen this used as a coating for wood-turned pens after sanding and staining in this video by Alex Harris of This Woodwork. Great stuff, super-duper cheap at dollar stores, and pretty chemically inert once it hardens.
Finally we have Epoxy. A critical component that is painfully familiar to anyone with experience in fibre-glassing, it’s basically liquid plastic. It will stick virtually any two objects together, where they be wood, plastic, metal, animal, vegetable or mineral. It’s great stuff and really fills-in the functionality gap where yellow glue falls short, it will bond metal to wood. You don’t need much of it, but you need to be fast, it hardens and thickens super quick, so be sure to have everything ready. It’s also a binary liquid, meaning that the epoxy and the resin hardener are both stable in and of themselves, but only harden when mixed. Very safe and has a long shelf-life. Spending a hundred bucks on a couple of gallons (~4x for litres) of epoxy and a few quarts (~equal to a litre) of hardener could last a woodworker for years. It’s pretty harsh stuff, though, so use in a well-ventilated area and use respirator equipment.
That’s just a taste of the vast world of woodworking techniques involving connecting two (or more!) pieces of wood together, now JOIN the club! Try it yourself! Hopefully your first try will work out better than mine; the poor dovetail never knew what hit it! Be sure to post some shots of your own work in the discussions below, and remark as to your favorite joinery style, why you like it, or any I missed! It’s not like I Could list everyone one of them.
I’m particular interested in some of the Asian joinery methods, some of those are simply stunning!