Splines are used in joining pieces of wood together. For joinery purposes, there are two aspects of wood. Grab a piece of wood and look at it: assuming a normal board shape, there are six sides, four of which have side grain and two of which have edge grain.

If you take two pieces of wood and slather some glue on the side grain of one and clamp it to the side grain on the other, the resulting joint is as strong as or even stronger than the wood. Thus you can take several boards, lay them edge to edge, and glue them into a table top. A darned strong table top.

But if you slap glue on the end grain of one piece and clamp it to the end grain or to the side grain of another piece, the resulting joint is extremely weak. It's weakest when it is end grain to end grain. It's frequently necessary to make a joint like this. The flag box I am building for you is one example. At the top corner it has two pieces of wood cut at a 45 degree angle, with the angled tips glued together. That's end grain to end grain. That joint won't stay together well. So what I do is cut a slit in each of the two beveled edges, about halfway through the wood. I then cut a thin slat of wood that fits into the kerf (the technical name for the slit. This greatly strengthens the joint. That thin piece of wood is called a spline. Watch episode 317 of the Lucille Ball Show, the one where she is making wooden boxes for Ethel to sell some crafts in. Ricky comes home and sees the boxes, which are falling apart because of the weak glue joints. At the top of his lungs he yells at her: "Looocy, you got some splinin' to do."

There are two primary uses for chisels: cutting holes in wood (primarily mortices) and for smoothing some aspect of a piece of wood, usually the end grain after a saw cut. For hole cutting we use chisels with a cutting blade that's perpendicular to the length of the blade. This gives us a flat bottom to the hole.

For smoothing end grain, I will lay the chisel flat on the wood and push across the grain to trim the end flat and smooth. The chisel cuts the wood better if you hold the cutting edge at an angle, because it is sawing the end grain rather than chopping it. Woodworkers frequently grind these cutting edges at an angle (a bevel) other than 90 degrees so they can lay the back of the chisel on the wood while doing the smoothing. This helps ensure a good flat surface, since more of the chisel is indexed on the wood. As we used to sing in Sunday school, "What a friend we have in chisels."


TEd