When choosing a band saw blade for performing curved cut on your workpieces, you must understand the relationship between the width of the blade and the minimum radius of the curves. The minimum cutting radius of a band saw blade is the smallest radius of a curve that can be followed by that saw blade without causing the blade to break or begin to drift away from the curves of the workpiece. The minimum cutting radius of a band saw blade is dependent upon the width of that saw blade; narrow saw blades has smaller minimum cutting radii than wider saw blades.
Thus, narrow saw blades can perform curved cuts that have small radii to their curves, while wider saw blades cannot follow curves that have small radii. One method of allowing wider saw blades to perform curved cuts is the use of relief cuts. The saw blade creates relief cuts by making a series of straight cuts along the edge of the workpiece into the portion of the workpiece that is to be removed (the waste area of the workpiece).
How to Choose a Band Saw Blade for Curved Cuts
Relief cuts work because the removal of small wedge of wood from the workpiece allows the saw blade to turn along smaller radii of the workpiece rather than along the long radius of the curved workpiece. By utilizing relief cuts, the radius of the curves created by the saw blade are within the minimum cutting radius of that blade. Thus, relief cuts allow saw blades to remain wider and reduce the number of time that the saw blade must be changed.
Another phenomenon to understand about band saw blades is the concept of blade drift. Blade drift is the phenomenon of a band saw blade that does not follow a perfectly straight line in the wood; instead, the saw blade may drift at an angle. The angle of the teeth of the saw blade or the alignment of the saws wheels may cause drift.
You can correct blade drift by simply making a test cut to determine the angle of drift of the saw blade. By measuring this angle with a bevel gauge, the fence of the saw can be adjusted to that angle. By adjusting the fence to the angle of drift of the saw blade, the blade will follow the saw table correct during both straight and curved saw cuts.
The rate at which the wood is fed into the band saw blade is referred to as the feed rate. Feed rate must be adjusted when cutting curves. When performing straight saw cuts, the feed rate can be maintained at a steady rate.
However, when cutting curves, feed rate must be slower. Feed rate must be slower when cutting curves to allow the teeth of the saw blade to clear any wood chips that may accumulate during the saw cut. Additionally, slower feed rate reduce the amount of heat generated by the saw blade; excessive heat may cause the teeth of the saw blade to scorch the wood.
The diameter of the saw saw wheels also has an impact upon the way in which the band saw blade perform its saw cuts. Small saw wheels force the band saw blade to bend more sharply during each revolution of the saw blade, and, therefore, small saw wheels are best used with narrow band saw blades. Wide saw wheels allow the saw blade to bend less sharply during each revolution, allowing the saw blade to utilize wider saw blades.
Each of these component must work within the same physical constraints of one another to allow the saw blade to function properly on the bandsaw. In selecting a band saw blade for a project that contains curved cuts, the saw blade that is selected should be one that can follow the tightest radius of the project. By first determining the radius of the tightest curve of the project, you can select the saw blade according to that radius.
By ensuring that a band saw blade is chosen that can follow the radius of the tightest curve, the saw blade will not break and the wood will not be ruined. Additionally, relief cuts can be used for projects that include both straight and curved cuts. Each of these steps will ensure that the saw blade track correctly and creates clean edges on the wood workpieces.
