Have you ever tried to build a campfire using logs from a freshly cut down tree? It doesn’t work very well does it? But if you build a campfire from logs from a tree that had been cut down a couple years before, it burns easily. You may also notice that the log from the freshly cut tree is a lot heavier then the log that was cut a couple years ago. That’s because a tree draws moisture from the ground in order to live. When you cut it down, that moisture is still trapped within the wood, but over time it evaporates out. So a log from a freshly cut tree will weigh more than one that’s been down for a while because of the weight of the water.

So why’s this important? Well, we know that the wood is going to dry over time. As it drys, its shape changes and it can even start to twist, bow, and even crack. We don’t want to start working with it only to have it twist or crack on us, so we wait until the wood is dry before working with it. This may take a couple years to dry to the point that we can start working with it, so lumber yards will use Wood Kilns to dry the wood faster. Figure 1 shows an industrial wood kiln. A wood kiln circulates hot air around the boards in order to dry them quicker. Notice that the boards are stacked on top of each other with a space between them. That way all the board’s surfaces are exposed to the circulating hot air allowing the board to dry quicker as well as dry evenly.

The lumber yard doesn’t completely dry the board. There’s still some moisture left in the wood. We call this the wood’s moisture content. This is a percentage of the amount of moisture left in the board. This is calculated as the weight before drying minus the weight after drying divided by the weight after drying, then multiplying that times 100 in order to get a percent as follows :

Didn’t know we were going to have to do math did you? Well you really don’t. We use moisture meters to determine the wood’s moisture content. Figure 2 shows a Pin Style Moisture Meter. It has two pins that you press against the grain of the board. Figure 3 shows a Contactless Moisture Meter. All you have to do with this style is lay it on the board.

Normally wood that you purchase from a lumber yard will have a moisture content between 7%-19%. Woods for interior projects you’ll want between 6%-8% moisture content and exterior projects are usually 9%-15% moisture content. Why’s this important? The lumber will absorb or evaporate moisture depending on the humidity of the environment that it’s in. Indoors the humidity is relatively low and pretty consistent. Outdoors the humidity can vary and in many cases it can be high. Depending on the humidity the wood will reach moisture content equilibrium, or a point at which it will no longer gain or loose moisture. Woodworkers use the term acclimate. You want to acclimate your wood for the environment that it’s going to be in before starting to work with it. Meaning that you’ll let it adjust to that environment (humidity level). Otherwise the wood could twist or crack once you move it into its intended environment. If you’re working on a project that’s going to remain indoors, you’ll want to work on it in a shop with a controlled environment. Meaning that the shops temperature and humidity is roughly the same as that of a normal house.

In some cases, like with music instruments, we’ll want an even lower moisture content (5%-6%), so they’ll have a small kiln in the shop. Once the wood is at the level of moisture they want, they’ll start woodworking it. Many times they’ll seal it afterwards in order to maintain the wood at that level of moisture content.

So, prior to starting your next woodworking project, you’ll want to know what environment you plan on using it in (indoors vs outdoors). Then establish the required moisture content you’ll need your wood at. This will save you the headache of having your project twist and crack on you.

In order to do woodworking, we need some wood, some lumber. I’m sure you’ve probably figured out by now that the lumber we purchase from Chelsea Lumber or any store comes from trees. The trees are harvested and brought to a lumber yard where they will be cut into boards. Figure 1 shows logs that have been cut to length and ready to be cut length wise into boards on a saw mill.

Figure 2 shows a log being cut on a sawmill. The lines drawn on the end of the log shows how the log will be cut. The pattern on the end will change depending on the size of board and type of cut that you want.

Depending on the orientation of how you cut the board you’ll get a different type of wood cuts. There are four typical types of wood cuts as shown in Figure 3: Plain Sawn, Quarter Sawn, Rift Sawn, and Live Sawn. As you can see in Figure 3, the grain appearance will change depending on the type of wood cut. Notice Quarter and Rift Sawn are similar. The difference is in the angle between the cut and the grain. The angle for Quarter Sawn is between 60 and 90 degrees, where the angle for Rift Sawn is between 30 and 60 degrees.

Figure 4 shows a stack of lumber similar to the lumber that you’d buy at a lumber yard. So you purchase some lumber and bring it to your wood shop to start making your project. However the wood is rough and it may be twisted and cupped. We need to smooth and flatten all four sides of the board. This is called S4S, surface four sides. We start this process off using a Wood Jointer to smooth and flatten two sides and in the process making them perpendicular to each other. Which means that they are square or form a 90 degree angle with each other.

Nate Harris, the owner of Harris Design, will demonstrate how to use a Wood Jointer in this short video.

You may be wondering why it’s called a jointer. The jointer creates smooth flat surfaces, which is necessary for jointing two pieces of wood together by gluing or bonding them. This is necessary to make larger boards. If you look at your kitchen table, it’s far too big to be just one board. It’s made up of multiple boards glued together. Figure 5 is an example of three boards glued together. The jointer makes the surfaces smooth and flat to ensure that there will be a good bond between the mating surfaces.

In conclusion, we use the Wood Jointer to smooth and flatten the side and edge of the board, which covers two of the four sides (S4S). Next time we’ll cover the Wood Planer, which will work the third side.