DRILLING MACHINES GENERAL INFORMATION

1 TC 9-524 Chapter 4 DRILLING MACHINESGENERAL INFORMATIONPURPOSEThis chapter contains basic INFORMATION pertaining to drillingmachines. A DRILLING machine comes in many shapes andsizes, from small hand-held power drills to bench mountedand finally floor-mounted models. They can performoperations other than DRILLING , such as countersinking,counterboring, reaming, and tapping large or small the DRILLING MACHINES can perform all of theseoperations, this chapter will also cover the types of drill bits,took, and shop formulas for setting up each plays a critical part in any operation involvingpower equipment.

2 This chapter will cover procedures forservicing, maintaining, and setting up the work, propermethods of selecting tools, and work holding devices to getthe job done safely without causing damage to the equipment,yourself, or someone DRILLING machine , called a drill press, is used to cut holesinto or through metal, wood, or other materials (Figure 4-1). DRILLING MACHINES use a DRILLING tool that has cutting edges atits point. This cutting tool is held in the drill press by a chuckor Morse taper and is rotated and fed into the work at variablespeeds. DRILLING MACHINES may be used to perform otheroperations.

3 They can perform countersinking, boring,counterboring, spot facing, reaming, and tapping (Figure 4-2).Drill press operators must know how to set up the work, setspeed and feed, and provide for coolant to get an acceptablefinished product. The size or capacity of the DRILLING machineis usually determined by the largest piece of stock that can becenter-drilled (Figure 4-3). For instance, a 15-inch drillingmachine can center-drill a 30-inch-diameter piece of ways to determine the size of the drill press are by thelargest hole that can be drilled, the distance between thespindle and column, and the vertical distance between theworktable and 9-524 CHARACTERISTICSAll DRILLING MACHINES have the following constructioncharacteristics (Figure 4-4): a spindle.

4 Sleeve or , head, worktable, and spindle holds the drill or cutting tools and revolvesin a fixed position in a sleeve. In most DRILLING MACHINES ,the spindle is vertical and the work is supported on ahorizontal sleeve or quill assembly does not revolve but mayslide in its bearing in a direction parallel to its the sleeve carrying the spindle with a cutting toolis lowered, the cutting tool is fed into the work: and whenit is moved upward, the cutting tool is withdrawn from4-2the work. Feed pressure applied to the sleeve by hand orpower causes the revolving drill to cut its way into thework a few thousandths of an inch per column of most drill presses is circular and builtrugged and solid.

5 The column supports the head and thesleeve or quill head of the drill press is composed of the sleeve,spindle, electric motor, and feed mechanism. The head isbolted to the worktable is supported on an arm mounted to thecolumn. The worktable can be adjusted vertically toaccommodate different heights of work. or it may beswung completely out of the way. It may be tilted up to90 in either direction, to allow for long pieces to be endor angled base of the DRILLING machine supports the entiremachine and when bolted to the floor, provides forvibration-free operation and best machining top of the base is similar to a worktable and maybeequipped with T-slots for mounting work too large forthe OF DRILLING MACHINESL ubricationLubrication is important because of the heat and frictiongenerated by the moving parts.

6 Follow the manufacturer smanual for proper lubrication methods. Clean each machineafter use. Clean T-slots. grooves. and dirt from belts andpulleys. Remove chips to avoid damage to moving all spindles and sleeves free of grit to avoid damagingthe precision fit. Put a light coat of oil on all unpaintedsurfaces to prevent rust. Operate all MACHINES with care toavoid overworking the electric CareOperations under adverse conditions require special care. Ifmachines are operated under extremely dusty at the slowest speeds to avoid rapid abrasive wear onthe moving parts and lubricate the MACHINES more extreme cold conditions, start the MACHINES at a slowspeed and allow the parts and lubricants to warm up beforeincreasing the speeds.

7 Metal becomes very brittle in extremecold. so do not strike the MACHINES with hard tools. Extremeheat may cause the motor to overheat. so use intermittent. oron and off, operations to keep the motor running OF DRILLING MACHINEST here are two types of DRILLING MACHINES used byTC 9-524 Reaming, counterboring, and counter-sinking may requireslower speeds than DRILLING and may not be able to beperformed for all materials on these personnel for repairing and fabricating neededparts: hand-feed or power-feed. Other types of drillingmachines, such as the radial drill press.

8 Numericallycontrolled DRILLING spindle drillingmachine, gang DRILLING machine , and turret drill press, are allvariations of the basic hand and power-feed drillingmachines. They are designed for high-speed production andindustrial depth is controlled by a depth-stop mechanismlocated on the side of the spindle. The operator of themachine must use a sense of feel while feeding the cuttingtool into the work. The operator must pay attention and bealert. to when the drill breaks through the work, because ofthe tendency of the drill to grab or snag the workpiece,Hand-FeedThe hand-feed DRILLING MACHINES (Figure 4-5) are thesimplest and most common type of DRILLING MACHINES in usetoday.

9 These are light duty MACHINES that are hand-fed by theoperator, using a feed handle. so that the operator is able to feel the action of the cutting tool as it cuts through theworkpiece. These DRILLING MACHINES can be bench or floor-mounted. They are driven by an electric motor that turns adrive belt on a motor pulley that connects to the spindlepulley. Hand-feed MACHINES are essentially high-speedmachines and are used on small workplaces that requireholes 1/2 inch or smaller. Normally, the head can be movedup and down on the column by loosening the locking it free of its holding device.

10 Due to the high speedwhich allows the DRILLING machine to drill different heights ofof these MACHINES , operations that require DRILLING speeds 450 revolutions per minute cannot be 9-524 Power-FeedThe power-feed DRILLING MACHINES (Figure 4-6) are usuallylarger and heavier than the hand-feed. They are equipped withthe ability to feed the cutting tool into the work automatically,at a preset depth of cut per revolution of the spindle, usually inthousandths of an inch per MACHINES are used in maintenance shops for medium-duty work, or work that uses large drills that require powerfeeds.