Metal-cutting bandsaw machines fall into two basic categories: vertical machines (Figure 7-2) and horizontal machines (Figure 7-3). Band saws use a continuous saw blade. Chip removal is rapid, because each tooth is a precision cutting tool and accuracy can be held to close tolerances eliminating or minimizing many secondary machining operations.
VERTICAL BANDSAWING MACHINE
The metal-cutting vertical band sawing machine, also called a contour machine, is made in a variety of sizes and models by several manufacturers. The size of a contour machine is determined by the throat depth, which is the distance from the saw band to the column. Figure 7-2 shows a typical contour machine and identifies its main parts, which are discussed below.
Figure 7-2 Vertical band sawing machine.
VARIABLE SPEED UNIT
The variable speed unit is located within the base of the machine. This unit consists of two V-type pulleys which are mounted on a common bearing tube. A belt on one pulley is driven by the transmission, while the belt on the other pulley drives the saw band drive wheel. The two outside cones of the pulleys are fixed, but the middle cone is shifted when the speed change wheel is turned. A shift in the middle cone causes the diameter of one pulley to increase and the diameter of the other pulley to decrease. This slowly changes the ratio between the two pulleys and permits a gradual increase or decrease in the speed of the machine.
HORIZONTAL BANDSAW MACHINE
The horizontal band sawing machine does the same job as the power hacksaw but does it more efficiently. The blade of the handsaw is actually a continuous band which revolves around a drive wheel and idler wheel in the band support frame. Two band guides use rollers to twist the band so that the teeth are in the proper cutting position. The guides are adjustable and should be adjusted so that they are just slightly further apart than the width of the material to be cut. This will give maximum support to the saw band and help assure a straight cut.
The vise on the horizontal bandsaw is much like the one on the power hacksaw. However, the horizontal bandsaw has a much greater capacity for large stock than does the power hacksaw. The stationary jaw can be set at several angles. The movable jaw adjusts automatically to whatever position the stationary jaw is in when the vise handwheel is tightened.
The horizontal bandsaw is operated hydraulically by controls on a control box, which is located on the front side of the machine. A motor and pump assembly supplies hydraulic fluid from a reservoir in the base to a cylinder, which raises and lowers the support arm and also controls the feed pressure and band tension. A speed and feed chart is sometimes provided on the machine, but when it is not, consult the operator's manual for the proper settings for sawing.
Figure 7-3. Horizontal bandsaw.
A coolant pump is located in one of the legs of the base, which serves as a coolant reservoir. The coolant cools the saw band and also washes away chips from the cut before they can clog the band.
- Milling Set-Up
- Machine Kits
- Granite CNC Kits
- Machining Handbook - adapted from the US Army's Handbook "Fundamentals of Machine Tools"
- Chapter 1. Introduction to the Machine Shop
- Chapter 2. Properties, Identification and Heat Treatment of Metals
- Chapter 3. Lathes
- Chapter 4. Milling Operations
- Chapter 5. Milling, Drilling And Slotting Attachments
- Chapter 6. Drilling Machines
- Chapter 7. Sawing Machines
- Chapter 8. Portable Machine Tools