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April 2002 Tooling the operator can vary the feed rate There is usually enough power avail able to make effective use of high speed steel or tungsten carbide saw blades rather than the high carbon steel blades used on light duty machines Coolant systems are also widely used on power table machines thus allow ing higher cutting speeds and higher feed rates along with longer blade life Many types of fixtures can be used on power table machines particularly when they are used for repetitive op erations A high production automated table machine is shown in Figure 15 5b Accessories Most bandsaws that do not have a coolant system have an air pump that directs a stream of air at the point where the blade is cutting the workpiece This removes the chips letting the operator see the layout lines clearly and provides some cooling If the machine has a fluid coolant system the tank and pump are usually located in the base A separate switch controls the pump Coolant systems are usually found on medium and heavy duty vertical bandsaws Blade welding attachments which are a specialized form of electric butt welding machines are a stan dard accessory on almost all bandsaws The blade welder usually consists of cast copper or bronze blade clamps a grinder a saw thick ness gage and the necessary switches and operating levers Weight operated feed devices can be used on bandsaws not fitted with power feed attachments This reduces operator fatigue and generally results in more uniform feed rates and longer blade life Other attach ments such as fix tures for cutting arcs and circles ripping fences and miters are used ex tensively on bandsaws Special fixtures for holding specific types of workpieces are of ten designed for use in mass production applications Horizontal Bandsaws Because horizontal bandsaws are used primarily for cutting bar stock and structural shapes they are also known as cut off saws The band type cut off saw is widely used because it is easy to set up and takes a narrow saw cut thus re quiring less power to operate and wast ing less material The cutting action is continuous and rapid The blade is supported close to either side of the material being cut so the cut is accu rate if the machine is properly adjusted and the blade is in good condition A typical horizontal bandsaw is shown in Figure 15 6a Horizontal bandsaws range in ca pacity from small fractional horse power machines Fig 15 6a to large heavy duty industrial saws as shown in Figure 15 6b The saw guides are an important factor in accurate cut off operations The saw blade has to twist as it leaves the idler pulley and the guides make the blade travel perpendicular to the material being cut Tungsten carbide inserts help minimize wear Figure 15 7 shows a more advanced horizon FIGURE 15 6a Typical horizontal bandsaw Courtesy Clausing Indus tries Inc FIGURE 15 5b Large heavy duty industrial horizontal bandsaw Courtesy Armstrong Blum Mfg Co FIGURE 15 7 Horizontal Band Saw with automated table stock feeding system Courtesy Kasto Racine Inc tal band saw with an automated table stock feeding system Controls and Accessories On light duty saws the controls are simple consisting mainly of an off on switch a means for changing blade speed and possibly a control for feed pressure On the larger machines a control panel is usually mounted on the saw head It consists of the necessary switches valves and instruments that indicate blade speed in feet per minute feed rate in inches per minute and other factors such as blade tension Some machines used for production work are capable of fully automatic operation and can be preset to cut a given num ber of pieces of work A counter is usually part of the instrumentation on semiautomatic and automatic ma chines There are coolant systems on almost all medium and heavy duty horizontal bandsaws The coolant extends blade life and allows higher cutting speeds and metal removal rates The operator controls the rate of coolant flow Solid lubricants such as wax or grease can also be used Wax in stick form is usually applied manually to the blade on light duty machines 15 4 3 Comparison of Hacksaws and Band Saws The decision as to which type of cut off saw to buy is often influenced by custom or habit However there are definite fac tors that can be considered Cost A hacksaw is much less expensive often about half the cost of a band saw of equal size and power Chap 15 Saws and Sawing 6 Tooling drive mechanism blade arbor vise feed mechanism and necessary guards and switches On some small saws the blade is fed into the work by hand Fig 15 10 On larger machines the feed mecha nism is pneumatically or hydraulically operated The operator controls the rate of feed Fig 15 11 The base of the machine or the vise can be swiveled to make angular cuts In some cases two machines can be set up on a single work stand for produc tion operations 15 7 1 Cold Saw Blades Blades smaller than 18 inches in di ameter are cut di rectly in the rim of the saw disk For cut ting soft materials the teeth are spaced farther apart as in the case of bandsaw and power hacksaw blades so that the gullet the space be tween the teeth will be large enough to accommodate large chips When cutting thin tubing or other thin materials use saw blades with closely spaced teeth to avoid chattering and tooth breakage Cold saw blades with teeth cut directly on the periphery of the disk may be made of high carbon or high speed steel Larger blades usually have seg mented teeth The body of the blade is made of rough resilient alloy steel and the inserted teeth are made of high speed steel or tungsten carbide The individual teeth or segments of three or four teeth are wedged or riv eted to the blade and can be easily replaced if a tooth is damaged or bro ken Larger cold saw blades can cut a kerf as wide as 1 4 inch and remove metal rapidly 15 8 Abrasive Cut Off Machines Abrasive cut off machines are used in many shops to cut metallic and nonmetallic materials Because an abrasive usually aluminum oxide is used as the cutting tool hardened steel can be cut without being annealed The cutting action here is faster than on other types of cut off machines Abrasive cut off machines may be of FIGURE 15 11 Large heavy duty industrial cold saw Courtesy Claus ing Industries Inc FIGURE 15 12 Abrasive cut off operation Courtesy Norton Company Chap 15 Saws and Sawing the wet or dry type The flow of cool ant usually water and an antirust chemical of some type are controlled by the operator The co