Technical Information Band SawsBlade Basics (continued) Tooth Set Raker Set These are individually set teeth — first right then left — followed by an unset tooth. The unset tooth (raker tooth) allows for fast chip removal and a straight cutting actions This tooth set is recommended for general purpose cutting applications. Wavy Set Wavy set teeth are set in groups, right and left, in varying degrees. Wavy set teeth are recommended for cutting light metal sections, such as sheet, tubing, and small solid shapes. Alternate Set In an alternate tooth set, every tooth is set — one left, one right — throughout the blade length. This tooth set is primarily used for cutting wood. Variable Set Variable set teeth are set in alternating groups with a single unset tooth (raker tooth). When these are combined with the varying set angles of the teeth, a faster, smoother, quieter cutting actions is achieved. Variable tooth blades perform extremely well on most applications and provide fast cutting on solids, shapes, structural, and piping. Wavy SetRaker SetAlternate SetVariable Set Successful Band Saw Operation and GeometriesGuidelines 21° R12° R7-1/4° R5-7/16° R3-3/4° R2-1/2° R1-7/16° R5/8° R5/16° RInchmm1-1/21-1/413/45/81/23/81/43/163832252016131065Width of Band SawMinimum Radii Cut Chart Blade Width Selection The dimension from tooth tip to back edge of the blade is the blade width. The greater the width, the greater the resistance to deflection while cutting. For straight cutting applications, use the widest blade the machine can accept. For contour cutting use the widest blade that the contour radius will permit, see Minimum Radii Cutting Chart to the right. Radii in this chart are based on manual feeding of one-inch thick milled steel. To cut close tolerance radii the following factors must be considered: • Blade width • Material thickness • Machinability • Feed force • Location of pivot point Teeth Per Inch The pitch of the blade is defined by the number of TPI (Teeth Per Inch). Non-ferrous materials such as brass, bronze, and aluminum require a large chip area. A low TPI, or "course" pitch, prevents the chips from clogging and binding together in the gullets, which can diminish sawing and damage the blade. On thin walled pipe, tubing, and sheet, many teeth per inch are required in order to avoid damaging or breaking the teeth. A low TPI blade is the best blade for cutting large cross- sections. The ability of each tooth to cut into the workpiece is increased because the saw's feed pressure is distributed over fewer teeth. A coarse pitch blade increases productivity and provides large chip clearing gullets. Blade Break-In Set Band Saw machine at the recommended speed for the material to be cut. When cutting easily machined metals, the cutting rate should be set at 1/3 to 1/2 of the recommended rate for the first 50 to 75 square inches. When cutting difficult to machine metals, such as tool steels or workhardened alloys, set the cutting rate at 3/4 of the recommended rate for the first 25 square inches. Gradually increase the feed until you achieve the recommended cutting rate after 50 to 60 square inches. continued on the next page
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