The biggest challenge in building something with wood is figuring out how to make two boards come together. Of course, in woodworking terms, this is called a wood joint. Now there are a lot of different types of wood joints — some joints are fairly easy to make, while other joints are much more involved and complex. So how do we decide which type of joint to use? The best way to answer that question is to first think about:
- What type of project you are building
- The tools you own
- The skills you have
First let’s take a look at the type of project you might have in mind. For example, building fine furniture for the home, like a desk, a cabinet, or a bookcase — usually requires some fairly sophisticated wood joinery:
- half lap joints
- cross-lap joints
- dados and grooves
- rabbet joints
- mortise and tenon joints
Also, these kinds of wood joints require some fairly sophisticated shop tools:
- Table Saw
- Dado Blade Set
- Router Table
- Drill Press
Now as much as I admire the quality and craftsmanship that goes into building projects like this, I think this level of woodworking might be out of reach for a lot of people. The tools can get very expensive, and it takes some time to learn how to use them. That’s why I’m always looking for alternative joints that can be made with fewer (and less expensive) shop tools — and joints that don’t require the skills of a master craftsman. Two of my favorite examples are:
Pocket Hole Joints
At first glance, a pocket hole joint resembles a simple butt joint – that is, two pieces of wood stuck together end to end. However, a butt joint by itself is relatively weak, and usually requires some complicated joinery or extra hardware to help hold the boards together. That’s where pocket hole joints come to the rescue. Now to make a pocket hole joint, you’ll need a pocket hole jig — a special tool that helps you drill a pilot hole (at 15 degrees) for driving pocket hole screws into an adjoining board. This creates such a remarkably strong joint that in most cases, you won’t even need to use glue.
Pocket hole joints are perfect for building things like:
- Carcass (the inner skeleton of a cabinet)
- Face frames (that you attach to a cabinet)
- Solid Wood Box
The best part about pocket hole joints is that you can build fairly complex furniture without spending a fortune on tools. All you need are a circular saw, a combination drill & driver, a pocket hole jig, and few hand clamps from around your shop. And once you get the hang of making pocket hole joints, your project ideas are limited only by your imagination.
Now let’s take a look at another type of simple and easy joinery that I call the “sandwich” joint. A sandwich joint very similar to a conventional half-lap joint, which is one of the most widely-used types of joinery in woodworking. And for good reason. Half lap joints are incredibly strong and durable. And that’s because of the extra gluing surface it provides. Now remember that the more gluing surface in a joint, the stronger the bond.
The only problem with conventional half lap joints is that they require some of the more expensive woodworking tools I mentioned earlier; tools that might also be difficult for beginners to use. That’s why I like the sandwich joint. It takes full advantage of the strength of a conventional half-lap, but is simpler, easier, and less expensive to make. The basic idea is to attach one board to the top of another, while leaving a wide overhang at the end. The overhang creates a “step” or a “lap” on to which another sandwiched board can be mounted. Bringing all four boards together in this fashion creates an incredibly strong joint, which can be just as strong as a conventional half-lap joint.
How it Works
- Create the Lap
The first task at hand in setting up a sandwich half lap is to figure out where to attach board #1 to board #2 (see illustration). Keep in mind that the “lap” we’re creating here should provide a perfectly-matched resting place for another “sandwiched” board that we’ll be attaching later. That means the size of the gap should match the width of the boards we’re using in the joint.
- Make the Sandwich
Once you’ve determined where to position the boards on top of each other, it’s time to make the sandwich. First I like to spread a thin layer of glue between the two adjoining boards, then secure them with a couple wood clamps or a few finish nails. If I’m using traditional woodworking glue (like Elmer’s), I like to let things dry overnight before moving on to the next step.
- Create the Joint
After the sandwiched boards are glued, dried and ready to go, it’s time to create the joint itself. I like to start by doing what woodworkers call “a dry assembly” — which means before I bring out the glue and woodscrews, I place the boards together just to see how they fit. If everything looks good, I can proceed with completing the joint.
There are several ways to go about completing a joint like this. Some builders like to use woodscrews or nails exclusively, while others avoid fasteners entirely, bringing half-lap joints together with nothing more than a few clamps and some glue. However, keep in mind that the glue-and-clamp method (no fasteners) requires a nearly perfect mesh between the two boards for the joint to work. That means starting with a surface that is super flat, straight, and square. That’s not so much a problem in a well-equipped woodworking shop, where less-than-perfect boards from a home center can be machined down to perfection with planers and jointers. For those of us who use boards as-is from the big-box store, we’re better off using some type of fastener in the joint.
Common woodscrews seem to work really well with the sandwich half-lap joint I’ve been talking about here. Of course the size of screws you’ll want to buy depends on the type of lumber you are using. You can download a free chart from my website that matches the correct size fastener to a particular board thickness. Get download here. The number of screws you’ll need also depends on the size of board you are using. For example, when building projects with 1x lumber (1x6s, 1x10s, 1x12s), I try to space my fasteners about 4 inches apart. That usually means driving three screws along the edge of the board.
To make sure my woodscrews are spaced evenly, I like to use a pilot hole guide (template) to mark where I’ll drill my pilot holes. This makes the whole process extremely quick and easy, and helps eliminate any chance of driving the woodscrews too close to the edge of a board.
Ideal Projects for Using Sandwich Half Laps
I’ve found the sandwich-half-lap method perfect for creating a basic frame (or “carcass”) for any number of different projects, like cabinets, tables, and simple boxes. Sandwich half laps are especially useful for building a simple shop workbench. By doubling up 2x4s to serve as legs, rails, and stretchers, you can create an amazingly strong and durable bench that will last a lifetime. You can find out more about building a workbench like this here.