Proper Cutting Direction for Side Grain Projects
Over the next few months we will be covering proper cutting techniques for a variety of different types of turning projects. This month we will begin by taking a look at one of the most popular types of projects...side grain turning such as bowls and platters.
With side grain turning projects, the grain of the wood runs perpendicular to the bed of the lathe, as shown in the photo above. What many turners do not realize is that they may or may not be cutting the wood in the proper direction in order to improve the quality of the wood's surface which they produce using their tool of choice. Let's take a look at how it should be done.
The most important thing to remember is that wood fibers need to be supported from behind in order for them to be cut cleanly, rather than broken off. When cutting the outside of a bowl, the tool should begin its cut at the smallest diameter, and end at the piece's largest diameter. The inset red circle shows an example of what the wood fibers would look like if greatly enlarged. By cutting in the direction indicated by the orange arrow, each wood fiber is supported by another longer fiber directly behind it. This will produce a smooth cut. If the cut is made in the opposite direction, then each wood fiber is not supported by another fiber directly behind it, causing the fibers to be broken or torn, resulting in a much rougher surface.
When cutting the inside of a bowl, the tool should begin its cut at the largest diameter, and end at the piece's smallest diameter. Again, by cutting in the direction indicated by the orange arrow, each wood fiber is supported by another longer fiber directly behind it. This will produce a smooth cut. If the cut is made in the opposite direction, then each wood fiber is not supported by another fiber directly behind it, causing the fibers to be broken or torn, resulting in a much rougher surface.
Heavily curved surfaces present a more unique set of challenges. In the photo above, the proper cutting direction is represented by the arrows. The same principles apply in this situation, but require a bit more thought. Just keep in mind that each cut on the outside will move from the smallest diameter to the largest, and that each cut on the inside will move from the largest diameter to the smallest.
Learning to cut wood properly, by making cuts where each wood fiber is supported to facilitate cutting rather than tearing or breaking, will greatly improve the quality of your wood's finish directly from the tool and reduce the time you'll spend later in sanding. Over the next few months we will be covering the proper methods for turning spindle projects, hollow forms (both end and side grain), and will also cover more advanced techniques for heavily figured and/or twisted grain patterns (special case situations).