On Wood Joints – On the House

On Wood Joints

By on August 17, 2015

Although we’ve made our living as builders for nearly a quarter century, our interest in construction began when we were just little tykes. Our dad had an old fashioned workshop that was filled with everything an inquisitive kid (or adult, for that matter) could dream of. Known simply as “the shop”, it boasted a bench grinder, a table saw, a drill press, a pipe vise and a bench vise.

There were also plenty of tools – power and hand tools. Who could forget the shiny chrome cased drill and sander or the drawer full of screwdrivers in every shape, size and configuration. There were also cans of this and pails of that and lots of scrap wood from past projects saved for future endeavors.

The concrete floor was a canvas splattered with paint from virtually every color of the rainbow. The wood top of the work bench was peppered with notches, cuts, gouges and dried glue, each of which could be traced to a previous project such as fixing a chair, building a bookcase or mending a window screen.

We attribute a good part of our interest in construction to our fascination with the shop and how our dad could miraculously transform an old stack of wood into a thing of beauty that mom inevitably found useful as a home for dishes, books, clothing or nick-knacks.

We learned early that a saw, some nails or screws, glue and a few sticks of wood along with some time and energy could produce very powerful results. We also learned that not all wood joints are alike. We discovered that the means by which two boards were attached had a lot to do with the appearance of what we were making and how well the joint held up. The two are often mutually exclusive. A “miter joint”, for example, is one of the cleanest looking joints, but is also one of the weakest.

A miter joint is used to hide the end grain of a board. Miter joints are traditionally used to make picture frames and for trim around windows and doors. Our earliest miters were made with a handsaw and a miter box that we made out of three pieces of wood screwed together. We used a carpenter’s square to cut a 45-degree angled slot into the miter box and we were off and running. With each use, the angles would become successively less accurate. Eventually, we traded up to a hand miter saw and table and now make all of our miter cuts on an electric miter saw.

Before we began making miter joints, we started with the easiest and most common of joints – the “butt joint.” We thought that it was called this kind of joint because we usually landed on our fannies with fatigue. This was hard work for little guys.

All kidding aside, a butt joint is made when joining the end of one board to the side or end of another. Butt joints are used pervasively in carpentry, but not nearly as often in woodworking or cabinet making. The key to making a strong butt joint is to use both fasteners (nails, screws, dowels) and glue. You can also use metal brackets if appearance will allow.

A variation of a butt joint that uses dowels for reinforcement is appropriately called a “dowel joint.” The wood must be carefully drilled, the boards perfectly aligned, and the dowels coated with glue to render the most professional results.

If you’ve ever made furniture or cabinets, chance are good that you’ve used a “lap joint.” There are several variations of this type of joint – half lap, full lap, end or corner lap, middle lap, cross lap and dovetail lap. The half lap is used to join wood of the same thickness. The two pieces of wood are notched half their thickness to make the connection. In contrast, a full lap is used to join boards of different thickness. For example, when joining a 1 by 4 to a 2 by 4, the 2 by 4 is notched ¾” (the thickness of a 1 by 4) to accept the 1 by 4. End, middle, cross and dovetail laps are variations of the half and full lap according to location and style.

A “rabbet joint” is most often used to assemble corners in drawers, cabinets, bookcases and the like. This particular joint is created by cutting a recess – called a “rabbet” – in the end of one piece to accommodated the second piece that is to be joined.

If you have ever had occasion to build a bookshelf with fixed shelves – the ends of which were recessed into the sides – the joint that you created is referred to as a “dado joint.” Cutting a groove or recess across the grain of one board into which a second board is inserted makes a dado joint. It is an attractive and strong means of joining two boards.

A sharp saw, a good carpenter’s square, a handful of fasteners, some glue and plenty of patience can good joints make. And remember, there is no substitute for safety. Always wear safety goggles and use tools (hand and power) in strict accordance with manufactures instructions and for the purpose designed.

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