The band saw consists of a continuous, thin steel blade that travels on two wheels. The blade is exposed where it passes through the table, or point of opera- tion. The table tilts for beveling. Blade guides posi- tion and control the blade above and below the table. The upper set of guides is on the guidepost above your work. The guidepost is mounted to the upper frame and typically includes a shroud to reduce the exposure to the blade. The post adjusts for different material thicknesses, is set 1/4″ (6 mm) above the material, and held by a lock knob. Most band saws have two wheels. The bottom wheel drives the blade. The top wheel turns freely and can be adjusted to control blade tension and alignment. Proper tension ensures the blade does not stray from the line of cut. With correct alignment, the blade tracks in the center of the wheels. The wheels have rubber tires to prevent damage to the blade’s teeth. The throat is the distance from the blade to the side frame. Refer again to Figure 23-41. This depth determines the widest cut that can be made. The throat depth is usually determined by the diameter of the wheels. See Figure 23-42A. There are band saws that have three wheels. They offer a large throat depth, but use smaller wheels. These machines are noted by their frame shape. Delta International Machinery Corp. Figure 23-41. Features of the band saw. Belt enclosure Upper blade guide Guidepost Blade Table Lower wheel guard Upper wheel guard Arm Changing Saw Blades The procedure for changing blades is as follows: 1. With the switch off, disconnect power and lock out the machine. 2. Remove the table insert. Back off the blade guides and thrust bearing above and below the table. 3. Remove or swing aside the upper and lower wheel guards. See Figure 23-42A. 4. Release the blade tension by turning the tension control knob. See Figure 23-42B. 5. Remove the old blade from the wheels and guides, and then slip it through the slot in the table. 6. Uncoil the replacement blade and install it on the machine. Be sure the teeth are facing the front of the machine and pointed downward toward the table. 7. Slide the replacement blade through the table slot, between the guides, and onto the wheels. 8. Reset the blade tension. Most machines have a scale to show the correct tension for various blade widths. See Figure 23-42C. 9. Turn the upper wheel by hand, three or four turns, to ensure that the blade is tracking in the center of the wheels. 10. Replace the wheel guards and throat plate. 11. Reconnect power to the machine. 12. Start the machine. Allow it to reach full speed, and then turn it off. Stop the machine with the foot brake if there is one. 13. Check that the blade location is correct for the saw being used. Refer to the operating instruc- tions. If not, adjust the tracking control knob that tilts the upper wheel slightly to bring the blade back into alignment. See Figure 23-43. When you are confident the blade is tracking properly, let the machine run 30 to 60 seconds so it can find its final resting place. 14. Adjust the blade guides, Figure 23-44. The front edge of the side guides should be even with or slightly in back of the tooth gullets. They should never touch the teeth. The rear guide (thrust bearing) should be 0.004″ (0.1 mm) away from the blade. Procedure Chapter 23 Sawing with Stationary Power Machines 391 Copyright Goodheart-Willcox Co., Inc.