Types of Wood
|The materials for most projects will fall into three categories: softwood, hardwood and manufactured panels such as plywood.
What you use for any given project depends on various factors: strength, hardness, grain characteristics, cost, stability, weight, color, durability and availability. Usually beginning woodworkers start out with a softwood such as pine. It's soft and easy to work so you don't need expensive tools to get good results. It is readily available at local lumberyards and home centers. It has it's limitations in furniture making, it is a soft wood and will damage easily.
Pine and most other softwoods will absorb and lose moisture more than hardwoods so are not as stable. Purchase the lumber at least two weeks before starting your project and keep it indoors. Place stickers (small pieces of scrap wood) between the boards to permit good air circulation around each piece of stock. This will allow the wood to reach an equilibrium with the indoor environment which reduces the likelihood of dramatic wood movement after a project is complete.
You will find that softwoods are sold in standard thickness and widths, for example a 1 X 4 will be 3/4" thick and 3 1/2" wide similar to construction materials. The material will usually be priced per lineal foot and the price will increase accordingly for the wider boards.
Panels made from strips glued together and sold as shelving are also available, these range from 12 to 24 inches wide and 2 to 8 feet in length.
At speciality stores the thickness of hardwood lumber is specified in quarters of an inch, measured when the wood is in a rough state. The thinnest stock is 4/4, representing 1 in., and the thickest usually available is 16/4, representing 4 in. Rather than being milled to specified dimensions, like pine, hardwoods are sold in random widths and lengths.
Hardwoods are sold by the board foot, which is defined as a square foot of rough lumber that is 1 in. thick. If a board is thicker than 1 in., the dealer multiplies the square footage by the thickness to arrive at the sale price. An 8/4 board will therefore cost twice as much as a 4/4 board of the same size.
Working with hardwoods is quite different from working with pine, you cannot drive a screw through hardwood lumber without first boring a pilot hole. Cutting and planing hardwoods requires extremely sharp tools.
Oak and ash, are known as open-grain woods. These species have alternating areas of relatively porous and dense wood, when stained the open-grain areas absorb the color readily while the harder areas are more resistant. This accentuates the grain patterns, creating a dramatic effect.
Plywood and Manufactured Sheets
You will likely be working with either plywood, consisting of an uneven number of alternating layers of wood, or a type of manufactured sheet.
Plywood and manufactured sheets often come in thicknesses that actually measure thinner than standard dimensions, for example a 1/4" router bit will be too wide you will need a 15/64" bit to cut a dado to fit it.
The two most common manufactured sheets goods used in furniture making are MDF (Medium Density Fiberboard) and Particle Board. Both are made from wood particles, combined with glue and bonded under pressure. MDF has finer particles than Particle Board so produces a smoother and stronger finished product.
MDF machines very well and is often used for moulded components on painted furniture. Its main draw back is that it is a very heavy product compared to real wood.
Hardwoods are also commonly used as outer veneers on manufactured sheets. These veneers are extremely thin sheets of wood that are glued to a panel core of plywood or particleboard. Such panels are usually 4'x 8' sheets, but they are available in other sizes, for example Baltic Birch is sold in 5' widths. Their thicknesses range from 1/8 inch to over 1 inch.
Because of their laminated construction, they are extremely stable in all dimensions. Since the veneers on any given panel are usually cut sequentially from the same log, the panel should display a uniform color and grain. Matching the grain pattern of solid wood to the generally uniform grain pattern on the panels can be difficult. But careful planning can yield good matches in the most visible areas of your project.