Set
The term “set” refers to the way in which the saw teeth are bent or positioned. Bending the teeth creates a kerf that is wider than the back of the blade.
Set patterns are usually selected depending upon the type of material that needs to be cut. Three common set patterns are shown in Figure 25.
The Regular, or Raker, set is generally furnished on blades which have 2 to 24 teeth per inch. These blades have one tooth set to left, one to right, and one unset tooth called a raker. The raker set is often used for contour cutting.
The Wave set is generally furnished on blades which have 8 to 32 teeth per inch. This set has groups of teeth bent alternately to left and right, which reduces the strain on individual teeth. Blades with a wave set are used where tooth breakage is a problem, such as in cutting thin stock or where a variety of work is cut without changing blades; also when the thickness of the workpiece changes, such as cutting hollow tubing or structurals.
The Straight set has teeth in a consistent, alternating pattern, which is good for fast, basic cuts where a fine finish is not important. This set is also popular for cutting wood and plastics.
Material
Some of the most common blade materials include:
Carbon Steel Blade – widely used because of its general adaptability for all types of work and for its lower cost. Excellent for cutting nonferrous metals and plastics.
High Speed Steel Blade – resists heat generated while cutting to a far greater extent than carbon steel blades. Best suited for cutting nonferrous metals.
Figure 25
Blade Breakage
Band saw blades are subject to high stresses and breakage may sometimes be unavoidable. However, many factors can be controlled to help prevent most blade breakage. Here are some common causes for breakage:
1.Misalignment of the blade guides.
2.Feeding workpiece too quickly.
3.Using a wide blade to cut a short radius curve.
4.Excessive tension.
5.Teeth are dull or improperly set.
6.Upper guides are set too high off the workpiece.
7.Faulty weld on blade.
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