Width
Band saw blades come in different standard widths, measured from the back of the blade to the tip of the tooth. Generally, wider blades are used for ripping or making straight cuts, such as resawing. Narrower blades are often used when the part being cut has curves with small radii. (When cutting straight lines with a narrow blade, the blade may have a tendency to wander, causing “blade lead.”)
Pitch
Pitch is measured in “teeth per inch” (T.P.I.) and can be constant or variable. Figure 35 shows blades with different pitches. A fine pitch (more teeth per inch) will cut slower but smoother. A coarse pitch (fewer teeth per inch) will cut rougher but faster.
As a rule of thumb, the thicker the workpiece, the coarser will be the blade pitch. If you have to cut a hard or very brittle material, you will probably want to use a blade with a finer pitch in order to get clean cuts.
Using a blade with too few teeth may cause vibration and a rough cut, while too many teeth may cause the gullets to fill with sawdust and overheat the blade.
As a general rule, use a blade that will have no fewer than 6 and no more than 12 teeth in the workpiece at any given time.
Shape
Figure 36 shows common types of tooth shape. Tooth shape has an effect on cutting rate.
The Regular blade, sometimes called a “raker” blade, has evenly spaced teeth that are the same size as the gullets, and a 0-degree rake angle. These offer precise, clean cuts at slower rates. It is usually a good choice for cutting curves.
The Skip type has fewer teeth and larger gullets, allowing faster cutting rates than the Regular type, with a slightly coarser finish. It is useful for re- sawing and ripping thick stock.
The Hook type blade has larger teeth and gullets and a positive rake angle for more aggressive, faster cutting when re-sawing or ripping thick stock.
Variable-tooth blades combine features of the other styles, and generally produce smooth, quiet cuts.
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Figure 35
Figure 36
