Using A Drill Press

Liam Pourhana

As a craftsman, you will use the drill press regularly. It is an important machine tool that not only lets you drill holes, but also lets you ream, counter-bore, countersink, and tap holes. A drill press makes holes of a set size in material. It does this by driving a drill bit. The drill bit is turned and this turning or rotary motion lets it cut into a material. This makes a circular hole the size of the drill bit diameter. In this module you will learn how to use the drill press to perform simple drilling tasks.

A drill press can come in various shapes and sizes depending on the use. Some are big enough for the drill press to stand on the floor, whereas smaller ones can be mounted on as workbench. There is another type that is used for drilling on mild steel metal sheet that has a magnetic base for holding the drill press. The bigger the drill press, the bigger the hole it can drill.

A basic drill press has the following parts, each with specific function:o on/off switcho speed controlo manual feed controlo spindleo chucko drill heado tableo base and columno viseo guard

ON/OFF SWITCHThe on/off switch is usually located on the front of the drill press with easy access. On some occasions, the manufacturers locate the switch on the side. The switch is linked direct to the electric motor that drives the drill press.

SPEED CONTROL GUIDEOn most pedestal drills, there are speed control guides to help the operator select the correct speed for the size of drill bit and material being drilled.

MANUAL FEED CONTROLThis lets you move or feed the drill bit down onto the material you want to drill a hole in. All drill press types have a hand feed control, although some also have an automatic feed control. Automatic feeds are usually set at a certain feed per revolution of the drill press spindle. That means, for every complete turn of the spindle, the drill bit lowers by a set amount. As an example, 0.10 mm (0.004") per revolution means that when the spindle rotates one revolution, the drill will move downwards 0.10 mm (0.004"). The range of feeds varies from 0.05 to 0.64 mm (0.002" to 0.025") per revolution depending on the drill press size.

SPINDLETurning, or rotation movement, is through the spindle. Depending on its type, the drill bit is secured either directly to the spindle or through a chuck to the spindle.

CHUCKThe chuck holds drill bits securely. You can use different chucks for very small or very large drill bits. Commonly a chuck takes up to 1/2" (12 mm) drill bits. Bigger drill presses can use a drill bit up to 3" (75mm).

DRILL HEADThe drill head contains the motor and drive mechanism for the drill spindle. The motor provides drive or turning movement to rotate the spindle and drill bit. The motor is normally found inside the drill head, so as to protect the operator from moving parts.A safety collar on the column stops the drill press head from falling when the locks are released unintentionally.Note: Always make sure the collar is in place and securely locked.

TABLEThis lets you position the work piece horizontally within the range of the spindle. Usually a vise is attached to the table. This lets you secure the work piece you are drilling.A table lock, secures the table at the height you want it at on the drill press column.The table-raising lift raises or lowers the table up or down the column.

The height or vertical size of the drill press is determined by the distance from the table in its lowest position, to the bottom of the jaws of the chuck when fully raised, less the amount the drill projects from the spindle or the chuck.

BASE AND COLUMNThe base and column support the drill press and prevent it from moving about the floor when in use. The base plate can also be used instead of the table. This lets you increase the vertical capacity of the machine.

ViceA vise is one way of securing an object to the drill table to enable drilling to take place

GUARDA drill press guard is a part used to protect you from any flying pieces of metal or other material coming from the drill while you are drilling. You must always make sure that the guard is properly positioned before you start the drill press.

There are a number of cutting tools that can be used on a drill press. The most common are:o drill bito center drillo countersink bito reamer

Twist DrillThe twist drill bit is the type produced in largest quantity today. It drills holes in metal, plastic, and wood.

Twist drills up to 1/2" (12 mm) diameter would normally be held in a chuck in the drill press. For larger holes you would use a drill bit with a Morse taper shank as shown in the image to the left. The tapered drill bit fits directly into the spindle, when the chuck is removed. The other image shows a typical drill bit with a morse taper fitting into the drill spindle.

You will notice that the point angle of the drill bit is 118°. This is the best angle for drilling mild steel. The angle can be changed depending on the material being drilled this diagram shows the drill point and the 118° angle.

Identification of Drill SizeThe drill size can be found by reading the engraved size on the bit, using the Vernier Caliper, or using the drill bit gauge. The sizes of drill bits are identified as follows:o number/letter gauge drill sizeo metric drill sizeo fraction/decimal drill size

Metric Drill SizeMetric drill bit sizes define the diameter of the bit in terms of standard metric lengths. Standards organizations define sets of sizes that are conventionally manufactured and stocked.

Fraction/Decimal Drill SizeFractional/decimal drill bit sizes are still in common use in the US. In the past, they were popular elsewhere, but now have been largely discarded in favor of metric sizes. One disadvantage of this scheme of sizing is that the size increment between drill bits is very large for the smaller sizes.

CENTER DRILLCenter drill bits are used in metalworking to provide a starting hole for a larger-sized drill bit or to make a conical indent in the end of a work piece on a center lathe. Although the original design was for use on machine tools, it is often used in bench work for layout purposes. It is also use for starting a hole for bigger drill bits. Twist drill bits may tend to wander when started on an unprepared surface. Once a bit wanders off-course it is difficult to bring it back on center. A center drill bit frequently provides a reasonable starting point as it is short and therefore has a reduced tendency to wander when drilling is started.

COUNTERSINK BITThe countersink cutter or bit, as the image to the right is used to provide a chamfer (angled edge) in the entrance to a drilled hole. This may be required to allow the correct seating for a countersunk-head screw or to provide the lead in for a second machining operation such as tapping. Countersink cutters are manufactured with six common angles, which are 60°, 82°, 90°, 100°, 110°, or 120°, with the two most common of those being 82° and 90°. Countersunk-head screws that follow the Unified Thread Standard very often have an 82° angle, and screws that follow the ISO standard very often have a 90° angle.

As you learned earlier, some materials are harder or softer than others. This means that some are easier to cut through than others. Because of this, you must set the drill press up correctly for the type of material you wish to drill. Charts are available to give you this information.

SPEEDRevolutions per minute (rpm) is how you say the speed of the drill. This means the number of times the drill bit turns in one minute. For example if a bit turns or rotates 100 times in one minute, the speed of the drill is 100 rpm. The speed control has its speed levels written in rpm. You must use the correct speed for the work piece to prevent damage or dulling of the drill bit. In general, use low speeds with hard, tough materials, such as medium carbon steel and stainless steel. Use high cutting speeds with softer materials, such as aluminum, copper, and low carbon steel. Tough materials have high resistance to cutting while soft materials have low resistance to cutting. Because drill bits are used at different speeds, the drill press has to be able to have its speed changed to suit. Although there are many manufacturers of drill presses, they all use either V-belts or variable speed mechanisms to drive, and control the speed of the drill bit.

The V-belt drive mechanism requires the operator the change the position of the V-belt from one pulley to another for speed change.The variable speed mechanism normally requires the operator to turn a handle, knob, or switch to achieve a speed change automatically by the drill press.

FEEDFeed is the distance traveled downwards and into a material as the drill bit turns. The feed control lets you adjust this amount. You will normally see feed shown as inches or mm per revolution of the drill bit. The feed you need changes with the drill bit size and the work piece material. Most drill presses have charts fastened to them showing the feed you should use. In general, use less feed when cutting hard tough materials, such as medium carbon steel and stainless steel. Use more feed when cutting softer materials, such as aluminum, copper, and low carbon steel. Feed rate is the speed at which the cutter is fed, that is, advanced against the work piece. It is expressed in units of distance per revolution, typically inches per revolution or millimeters per revolution.

FEED/SPEED CHARTTable 1 shows an example of a speed/feed chart. If your drill press has a chart, you must use the figures given on that machine.

SUMMARY You have learned the meaning of speed and feed. Material types affect the drill press control settings. You have also learned how to find the correct speed and feed settings you need for different materials and drill bits.

Safety Rules for the Drill Press

You know the general workshop safety rules. You know you must follow them whenever you are in a workshop. When you work on a drill press there are extra safety rules you must follow. These drill press safety rules must be followed as well as the general safety rules.

Before you even begin a task on a drill press you must think of safety. Remember, safety starts with you.

IN-USE SAFETY RULESWhile you are performing drilling tasks you must remember safety.

AFTER-USE SAFETY RULESEven when you have completed your drill task, you must still think of safety

SUMMARY In this module, you have learned to identify a drill press and its use. You can identify drill press parts and controls and you know their functions. You know how to find the correct speeds and feed each work piece material needs and can adjust them as needed. Finally, you learned the drill press safety rules needed before, during, and after use.