Wood Furniture - Woods and Joints
There are different kinds of wood that furniture can be constructed from. And there are different joints that can be used to hold the parts of the furniture together. Here's an overview of what you might be working with.
There are three basic types of wood you can work with-hardwood, softwood, and plywood. (A lot of furniture you see today is made with particle board or pressboard as well. This type of wood is very difficult to saw or cut and is not suitable for work at home.)
Hardwoods come from trees with broad leaves or at least without needles such as cherry, mahogany, maple, and oak. As the name implies, these woods usually (though not always) have a hard surface. This can make them a little more difficult to work with for cutting, carving, and detail work. But it also makes them stronger and more stable.
Softwoods come from needle-bearing trees such as pine, spruce, and cedar. Being softer, they are easier to cut, carve, and do other detail work on. However, the soft surface also means that they're more likely to show dings and scratches. And for flat, horizontal surfaces, especially those that will be sat on, they'll need more support to keep them from sagging.
Plywood is put together with thin sheets of wood material and glue or some other bonding. Typically these sheets consist of 5-ply or 7-ply boards that offer greater strength, stability, and durability than a similarly thick piece of wood. This makes plywood especially useful for strengthening non-visible portions of furniture.
You can use several different joints to put the wood together. Here are some of the common options.
Mortise and Tenon
One of the pieces of wood has a notch (mortise) cut into it. The other piece is cut to have a projection (tenon) that fits into that notch. The fit should be as tight as possible, and the joint should be glued for added support.
Both of the pieces has two round holes drilled or bored into them where they are going to be joined. Two dowels that fit the holes are inserted in both and the pieces are pushed together so the dowels are not visible. Glue is helpful in keeping this joint together.
You may be most familiar with this kind of joint from the extra leaf in your dining room table. Like mortise and tenon, tongue-in-groove involves a notch in one piece and a projection in the other. But the two pieces are not joined at an angle. Rather the one piece is an extension of the other. This joint is not designed to support weight.
A dovetail joint has notches cut in both pieces so they fit together like a puzzle. This joint is often used in drawers.
Two boards are cut at an angle so they join together at a perfect 90 degrees. The joint is held together with screws, nails, or dowels.
Triangular wood blocks are cut to fit the corners and glued or screwed in place. They can further secure weight-bearing joints in chairs and other places.