PORTABLE DRILLS : PURPOSE AND TYPES

The portable drill is a hand-supported, power-driven machine tool that rotates twist drills, reamers, counterbores, and similar cutting tools. The portable drill may be electrically powered by means of an internal electric motor (Figure 1) or may be pneumatically powered (Figure 2). Portable drills are rated by the maximum size hole that can be drilled in steel without overtaxing the motor or drill.

TALADROS PORTÁTILES : PROPÓSITO Y TIPOS

El taladro portátil es una máquina herramienta de soporte manual, accionada por motor que hace girar brocas helicoidales, escariadores, avellanadoras, y herramientas de corte similares. El taladro portátil se puede accionar eléctricamente por medio de un motor eléctrico interno (figura 1) o puede ser accionado neumáticamente (figura-2). Los taladros portátiles son clasificados por el tamaño máximo del agujero que puede ser perforado en el acero sin una exigencia excesiva del motor o de la mecha.

Fig. 1- Portable electric hand drills - Taladros manuales portátiles eléctricos

Fig. 2 - Portable pneumatic hand drills - Taladros manuales portátiles neumáticos

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DEWALT Reconditioned Heavy-Duty VSR Drill - 1/2in., Model# DW232GR $79.99 This DeWalt factory-reconditioned Heavy-Duty Drill is the same high-quality unit as a new DeWalt tool. The reconditioned tools go through an even tougher quality inspection than the new tools, including two full-quality inspections by DeWalt, plus an added quality inspection by Northern. DeWalt reconditioned tools come with a 12-month parts and labor warranty. Amps: 7.8, Chuck Size (in.): 1/2, Speed (RPM): 0 - 850, Side Handle: Yes, Keyless Chuck: No, Variable Speed: Yes, Case Included: No Heat-treated gears for durability Metal gear housing Double gear reduction 360 side handle [Read more] Store: Northern Tool and Equipment Brand: Dewalt - DEWALT Compact Cordless Drill/Driver Kit - 18 Volt, 1/2in., Model# DCD760KL $219.99 The DEWALT Compact Cordless Drill/Driver has a lightweight design to minimize user fatigue, as well as a compact size to allow users to fit into tight spaces. Dual speed range delivers optimal performance. LED work light provides increased visibility in confined spaces. Max. Torque (in.-lbs.): 350 UWO, Volts: 18, Speed - No Load (RPM): 0 - 500 / 0 - 1, 700, Chuck Size (in.): 1/2, Keyless Chuck: Yes, Clutch Settings: 17, Reversible: Yes, Variable Speed: Yes, Battery Included: Yes (2), Charger Included: Yes, Case Included: Yes, Tool Weight (lbs.): 4 [Read more] Store: Northern Tool and Equipment Brand: Dewalt - Milwaukee Hole Hawg Electric Drill - 1/2in., 900 RPM, 7.5 Amp, Model# 1670-1 $319.99 Power and torque, thats about all that needs to be said about the Hole Hawg line of drills. The compact design of this drill makes it perfect for drilling between studs and joists. An extra-long pipe handle helps you control the power. Amps: 7.5, Chuck Size (in.): 1/2, Speed (RPM): 900, Side Handle: Yes, Keyless Chuck: No, Case Included: No 1/2in. capacity in steel Handles up to 29/16in. selfeed bit Reversing Triple gear reduction [Read more] Store: Northern Tool and Equipment Brand: Milwaukee - DEWALT XRP Drill/Driver - 1/2in. Drive, 12 Volt, Model# DCD910KX $189.99 The DEWALT XRP Drill/Driver is great for any job, with a patented 3-speed all-metal transmission that matches the tool to task for optimal speed and run time. Max. Torque (in.-lbs.): 285 UWO, Volts: 12, Speed - No Load (RPM): 0 - 425 / 0 - 1, 200/0 - 1, 800, Chuck Size (in.): 1/2, Keyless Chuck: Yes, Clutch Settings: 22, Reversible: Yes, Variable Speed: Yes, Side Handle: No, Battery Included: Yes (2), Charger Included: Yes, Case Included: Yes Heavy-duty 1/2in. chuck helps prevents bits from falling out High-efficiency motor delivers 285 Watts of power for superior performance XRP batteries for long run time and battery life LED worklight for visibility in confined areas 3 speed settings [Read more] Store: Northern Tool and Equipment Brand: Dewalt JET Floor Drill Press - 20in., Model# JDP-20MF $1,099.99 Floor drill press has a 1in. drilling capacity, a 1 1/2 HP, single-phase 115/230V motor and a hinged metal belt and pulley cover coupled with quick adjustment motor mount allow rapid changing of spindle speeds. Features adjustable tension spindle return spring and built-in work lamp (bulb not included). Item is on backorder until September 7th. HP: 1 1/2, Volts: 115 / 230, Speeds (qty.): 12, Drilling Capacity (in.): 20, Chuck Size (in.): 3/4, Dimensions L x W x H (in.): 19 x 33 x 67 12 spindle speeds Rotating, 45 tilting, crank-operated worktable with quick release clamp On/off switch located on front of the drill press head A 1/2in. dia. external positive depth stop with 3-nut locking feature for quick adjustment Spindle is supported by high quality ball bearings 3/4in. drill chuck and key included 3 3/8in. column dia. 19in.W x 33in.D x 67in.H [Read more] Store: Northern Tool and Equipment Brand: Jet - DEWALT Compact Cordless Drill/Driver - Tool Only, 18V, 1/2in., Model# DCD760B $109.99 The DEWALT Compact Cordless Drill/Driver features a lightweight design to minimize user fatigue. Dual speed range delivers optimal performance. LED worklight provides increased visibility in confined spaces. Compact size allows users to fit into tight spaces. SAVE MONEY by replacing or adding specific tools that work with the XRP , XRP Lithium-Ion or Compact Lithium-Ion battery and charger you already own. The DeWalt 18V bare tool system lets you choose the tool you need to get the job done without buying a complete kit. Add a DeWalt bare tool to your 18 Volt cordless system today. Max. Torque (in.-lbs.): 350 UWO, Volts: 18, Speed - No Load (RPM): 0 - 500 / 0 - 1, 700, Chuck Size (in.): 1/2, Keyless Chuck: Yes, Clutch Settings: 17, Reversible: Yes, Variable Speed: Yes, Battery Included: No, Charger Included: No, Case Included: No, Tool Weight (lbs.): 3 Tool only; battery sold separately [Read more] Store: Northern Tool and Equipment Brand: Dewalt - Bosch 18 Volt Brute Tough Cordless Drill/Driver, Model# 35618 $249.99 The Bosch 18 Volt Brute Tough Cordless Drill/Driver delivers an impressive 600 in-lbs. of torque for the tough jobs. Max. Torque (in.-lbs.): 600, Volts: 18, Speed - No Load (RPM): 0 - 450 / 0 - 1, 800, Chuck Size (in.): 1/2, Clutch Settings: 25, Side Handle: Yes, Battery Included: Yes (2) 18V, Charger Included: Yes, Case Included: Yes 1/2in. metal chuck for increased durability and grip force 25-position clutch Fully replaceable motor brushes, variable speed trigger with soft grip handle [Read more] Store: Northern Tool and Equipment Brand: Bosch - Bosch SDS-Plus Concrete Drill - 5/8in. Chuck, 4.8 Amp, Model# 11258VSR $159.99 This Bosch 5/8in. SDS-Plus concrete drill features a lightweight, compact design that is perfect for for small diameter drilling. Two-mode selector switches from rotary hammer mode to rotation-only mode. Amps: 4.8, Chuck Size (in.): 5/8, Speed (RPM): 0 - 4, 400, Case Included: Yes Lightweight, compact design for small diameter drilling 360 auxiliary handle with built-in quick release depth gauge [Read more] Store: Northern Tool and Equipment Brand: Bosch Klutch Floor-Mount Drill Press - 12 Speeds, 1 1/2 HP, 17 3/4in. Swing $599.99 The Klutch Floor-Mount Drill Press gives you precision drilling and pinpoint accuracy in one powerful machine. 12 speeds ensure proper application for a variety of different jobs. Features wide base, rotating table and built-in LED light. HP: 1.5, Volts: 120, Speed (RPM): 180 - 2, 940, Speeds (qty.): 12, Vertical Stroke: 4 3/4in., 360 Head Swivel: Yes, Draw Bar: No, Swing: 17 3/4in., Chuck Size (in.): 3/4, Worktable L x W (in.): 13 3/4 x 13 3/4, Light Included: Yes, Dimensions L x W x H (in.): 35 x 17 x 65.7 18 1/2in. x 14 3/16in. base [Read more] Store: Northern Tool and Equipment Brand: Klutch - DEWALT Heavy-Duty VSR Right Angle Drill - 3/8in., Model# DW160V $169.99 The DEWALT Right Angle Drills 100% ball-bearing construction provides durability and longer tool life. Compact right angle design for easy access in tight places. Paddle switch is ideal for use in awkward positions and limited access areas. Shielded chuck protects user and improves grip in confined areas. Double gear reduction increases torque performance and decreases gear stress. Amps: 3.7, Chuck Size (in.): 3/8, Speed (RPM): 1, 200, Side Handle: No, Keyless Chuck: No, Variable Speed: No, Case Included: No 200 Watt motor Capacity in Wood (Spade Bit): 1 1/8in. Capacity in Wood (Hole Saw): 1 1/8in. Capacity in Steel (Twist Bit): 3/8in. Capacity in Steel (Hole Saw): 3/4in. [Read more] Store: Northern Tool and Equipment Brand: Dewalt - Makita Electric Drill - 1/2in. Chuck Size, 550 RPM, 6.3 Amp, Model# 6013B $179.99 This 1/2in. reversible drill features a rocker-type switch for easy, one-handed forward or reverse operation. Its D-handle rotates 360 for multi-position operation. And youll get more torque for your money with a double-gear reduction system. Amps: 6.3, Chuck Size (in.): 1/2, Speed (RPM): 550, Side Handle: Yes, Keyless Chuck: No, Variable Speed: No, Case Included: No Ball and needle bearing construction for longer tool life and smooth operation Chuck key storage slot in tool handle Heavy duty industrial drill chuck for positive bit retention and accurate drilling Capacities: Steel 1/2in. Wood 1 3/8in. 115 Volts Overall length 13 3/8in. Model 6013BR [Read more] Store: Northern Tool and Equipment Brand: Makita Chicago Pneumatic Reversible Angle Air Drill - 3/8in., 1800 RPM, 4 CFM, Reversible, Model# CP879 $99.99 The Chicago Pneumatic 3/8in. reversible angle air drill features a compact, low profile head for drilling in confined areas. Features reverse valve and teasing throttle for control from start up through run down. Chuck Size (in.): 3/8, Keyless Chuck: No, Air Consumption (CFM): 4, Speed (RPM): 1, 800, Air Inlet Size (in. NPT): 1/4, Min. Hose Size (in.): 3/8, Reversible: Yes, Side Handle: No, Tool Weight (lbs.): 2 1/4, Tool Length (in.): 8 1/4 Compact, low profile head for drilling in confined areas Rear exhaust directs air away from workpiece Reverse valve for simple directional changes Applications: Screwdriving and drilling in hard to reach places [Read more] Store: Northern Tool and Equipment Brand: Chicago Pneumatic - Makita Electric Drill - 1/2in. Chuck Size, 550 RPM, 6.5 Amp, Model# 6302H $144.99 This 1/2in. drill boasts a hefty 6.5 Amp motor for continuous production work. Its industrial metal gear housing means this tool will last for many years to come. U.S.A. Amps: 6.5, Chuck Size (in.): 1/2, Speed (RPM): 550, Side Handle: Yes, Keyless Chuck: No, Variable Speed: Yes, Case Included: No Reversible Weighs only 4.8 pounds Lock-on button for long jobs Side handle can be attached to either side of tool Belt clip for portability Double insulated Model 6302H [Read more] Store: Northern Tool and Equipment Brand: Makita - DEWALT XRP Drill/Driver - 1/2in. Drive, 14.4 Volt, Model# DCD910KX $199.99 The DEWALT XRP Drill/Driver is great for any job, with a patented 3-speed all-metal transmission that matches the tool to task for optimal speed and run time. Max. Torque (in.-lbs.): 325 UWO, Volts: 14.4, Speed - No Load (RPM): 0-425 / 0 - 1, 200 / 0-1, 800, Chuck Size (in.): 1/2, Keyless Chuck: Yes, Clutch Settings: 22, Reversible: Yes, Variable Speed: Yes, Side Handle: Yes, Battery Included: Yes (2), Charger Included: Yes, Case Included: Yes Heavy-duty 1/2in. chuck helps prevents bits from falling out High-efficiency motor delivers 325 Watts of power for superior performance XRP batteries for long run time and battery life LED worklight for visibility in confined areas 3 speed settings 360 side handle [Read more] Store: Northern Tool and Equipment Brand: Dewalt - Makita Electric Drill - 3/8in. Chuck Size, 1200 RPM, 5.2 Amp, Model# 6402 $119.99 This drill boasts a powerful 5.2 Amp motor for excellent performance, coupled with double gear reduction for extra power. Variable speed lets you easily drill a variety of materials. Amps: 5.2, Chuck Size (in.): 3/8, Speed (RPM): 1, 200, Side Handle: No, Keyless Chuck: No, Variable Speed: Yes, Case Included: No Reversing switch Well balanced, weighs only 3.7 pounds Lock-on button Ball and needle bearing construction Belt clip Model 6402 U.S.A. [Read more] Store: Northern Tool and Equipment Brand: Makita - DEWALT Heavy-Duty Spade Handle Drill - 1/2in., Model# DW130V $184.99 Spade handle drill with 1/2in. chuck size, triple gear reduction and 9.0 Amp motor. U.S.A. Amps: 9, Chuck Size (in.): 1/2, Speed (RPM): 550, Side Handle: Yes, Keyless Chuck: No, Variable Speed: Yes, Case Included: No Variable speed reversing switch avoids air bubbles when mixing mud and better control when drilling 2-position rear spade handle for greater control when drilling or mixing Triple gear reduction and low 550 RPM for increased torque Capacity in wood (Spade Bit): 1 1/2in. Capacity in wood (Self-Feed): 2 9/16in. Capacity in wood (Hole Saw): 5in. Capacity in wood (Auger Bit): 1 1/2in. Capacity in steel (Hole Saw): 3in. UL listed [Read more] Store: Northern Tool and Equipment Brand: Dewalt - DEWALT VSR Pistol Grip Drill - 10 Amp, 1/2in. Chuck, Model# DWD210G $129.99 This DEWALT drill has a powerful 10 Amp motor, great for drilling in wood and steel. Amps: 10, Chuck Size (in.): 1/2, Speed (RPM): 0 - 1, 200, Side Handle: Yes, Variable Speed: Yes Motor with overload protection Metal gear housing Soft-grip handle and two-finger trigger for comfort and versatility Spade bit drilling applications in wood up to 1 1/2in. Selffeed bit drilling applications in wood up to 2 9/16in. Hole saw drilling applications in wood up to 3 5/8in. Auger bit drilling applications in wood up to 1 1/2in. Twist bit drilling applications in steel up to 1/2in. Hole saw drilling applications in steel up to 2in. [Read more] Store: Northern Tool and Equipment Brand: Dewalt - DEWALT Heavy-Duty Cordless Right Angle Drill Kit - 14.4 Volt, 3/8in., Model# DW966K-2 $199.99 Max. Torque (in.-lbs.): 310, Volts: 14.4, Speed - No Load (RPM): 0 - 400 / 0 - 1, 250, Chuck Size (in.): 3/8, Keyless Chuck: Yes, Reversible: Yes, Variable Speed: Yes, Side Handle: No, Battery Included: Yes, (2) 14.4V batteries, Charger Included: Yes, 1-hr. charger, Case Included: Yes Maximum torque for heavy-duty applications such as turning large bits and fasteners Multi-grip trigger provides comfort and convenience by allowing the user to get into tighter spots while still having access to trigger Variable speed and reversing gives the user the ability to control speed for greater accuracy and the convenience of reverse Durable, right angle transmission with sealed ball bearings for longer tool life Model DW966K-2 [Read more] Store: Northern Tool and Equipment Brand: Dewalt - DEWALT Cordless Compact Right Angle Drill Kit - 18 Volt, 3/8in., Model# DCD690KL $269.99 The DEWALT 18V Compact Right Angle Drill features dual speed ranges for increased user flexibility providing a wide range of applications. Compact length allows users to fit into hard to reach spaces. Multi-grip trigger provides comfort and convenience by allowing the user to get into tighter spaces while still having access to the trigger. Max. Torque (in.-lbs.): 320 UWO, Volts: 18, Speed - No Load (RPM): 0 - 500 / 0 - 1, 500, Chuck Size (in.): 3/8, Keyless Chuck: Yes, Reversible: Yes, Variable Speed: Yes, Battery Included: Yes (2), Charger Included: Yes, Case Included: Yes, Tool Weight (lbs.): 3.9 Dual speed ranges (0-500/0-1500) RPM for increased user flexibility providing a wide range of applications Compact Li-Ion batteries (DC9181) are compatible with the existing system of DEWALT 18V power tools produced since 1996 [Read more] Store: Northern Tool and Equipment Brand: Dewalt Ingersoll Rand Reversible Quiet Technology Air Drill - 1/2in. Keyed Chuck, Model# 7803RA $209.99 This Ingersoll Rand reversible air drill features a lightweight, compact aluminum housing and reversible motor with quick-release lever. Variable-speed trigger for precise speed control. Chuck Size (in.): 1/2, Keyless Chuck: No, Air Consumption (CFM): 4, Speed (RPM): 500, Air Inlet Size (in. NPT): 1/4, Min. Hose Size (in.): 3/8, Variable Speed: Yes, Reversible: Yes, Side Handle: No 99.1dB noise level [Read more] Store: Northern Tool and Equipment Brand: Ingersoll Rand

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Therefore, a 1/4-inch-capacity drill is capable of drilling a 1/4-inch diameter hole or smaller in steel. Portable electric and pneumatic drills rated at 1/4 to 1/2-inch maximum capacities are usually equipped with geared drill chucks for mounting straight, round shank twist drills or other similar tools by using a chuck key (Figure 3). Heavier portable drills (Figure 4) having a 3/4- to 1 1/4-inch capacity use taper shank chucks to mount drills and other similar tools.

Fig. 3 - Geared drill chuck and chuck key. - Cabezal portabroca o mandril dentado y llave de ajuste de mandril.

Portable drills have many different characteristics (Figure 5) depending on how the job is to be done. They may be set for one speed or they maybe variable speed drills. A variable speed drill is an excellent tool for use as a power screwdriver.

Portable drills may be equipped with a reversing switch to allow a screwdriver attachment to reverse bolts and screws out of holes. Special 90° angle portable drills (Figure 8) are available for drilling in confined spaces where a standard size drill will not have sufficient clearance. For corners and tight spots, a 360° angle portable pneumatic drill (Figure 2) is available which can be swiveled to any desired angle and locked into position. Most portable drills have a lock button near the on-off switch which allows for continuous operation without holding the trigger. Side handles and rear spade handles (Figure 5) can be attached to most drills to stabilize drilling and to allow for better control. Special devices, such as a vertical stand (Figure 6) or feed screw (Figure 7), can be used on some of the portable drills to make a job easier or more proficient.

Fig. 5 - Common portable drill - Taladro portátil común

The size, type, and power capacity of portable drills selected depends on the job to be performed. Before attempting a drilling job, check the capabilities of the portable drill with the manufacturer's instruction manual .

Fig. 7 - Operation of the portable drill showing the use of the feed screw - Operación del taladro portátil mostrando el uso del tornillo de accionamiento de avance

Por lo tanto, un taladro ¼ pulgadas de capacidad es capaz de perforar un agujero de ¼ pulgada de diámetro o más pequeño en acero. Los taladros eléctricos y neumáticos portátiles clasificados en ¼ a ½ de pulgada de capacidades máximas son generalmente equipados con manguitos porta broca dentados para el montaje de brocas rectas, de espiga redonda u otras herramientas similares usando una llave de mandril (figura 3). Taladros portátiles más pesados (figura 4) que tienen capacidades de ¾ - a 1 ¼ pulgadas usan espiga de forma cónica para montar las brocas y otras herramientas similares.

Fig. 4 - 1 inch capacity portable electric drill - Taladro eléctrico portátil de 1 pulgada de capacidad.

Los taladros portátiles tienen diversas características (figura 5) dependiendo de cómo debe ser hecho el trabajo. Pueden ser ajustados para una velocidad o pueden ser taladros de velocidad variable. Un taladro de velocidad variable es una herramienta excelente para su uso como destornillador eléctrico.

Los taladros portátiles se pueden equipar con un interruptor de inversión para permitir que un accesorio del destornillador destornille pernos y tornillos de los agujeros. Taladros portátiles especiales de 90° de ángulo (figura 8) están disponibles para perforar dentro de espacios confinados donde un taladro de tamaño estándar no tendrá suficiente espacio. Para las esquinas y puntos con poco margen, un taladro neumático portátil de 360° de ángulo (figura 2) está disponible para que se pueda hacer girar sobre un eje a cualquier ángulo deseado y ser trabado en una posición. La mayoría de los taladros portátiles tienen un botón de traba cerca del interruptor de encendido-apagado que permite una operación continua sin accionar el disparador. Los mangos laterales y mangos posteriores tipo espada (figura 5) se pueden fijar a la mayoría de los taladros para estabilizar la perforación y para disponer de un mejor control. Los dispositivos especiales, tales como el soporte vertical (figura 6) o eje de avance (cuadro 7), se pueden utilizar en algunos de los taladros portátiles para hacer un trabajo más fácil o más eficiente.

Fig. 6 - Portable electric drill with vertical stand - Taladro eléctrico portátil con soporte vertical

El tamaño, el tipo, y la capacidad eléctrica de los taladros portátiles seleccionados dependen del trabajo a ser realizado. Antes de intentar un trabajo de perforación, compruebe las capacidades del taladro portátil con el manual de instrucciones del fabricante.

Fig. - Hand drilling operation in confined space using the 90° angle drill - Operación de taladrado manual en espacios estrechos usando el taladro angular de 90°

DRILLING OPERATIONS

Operation of the portable electric and pneumatic drills differs from recommended operating procedures for the upright drilling machine. The portable drill is hand supported for most operations, and the cutting speed of the drill is fixed or dependent upon the operator to control. When hand supported, the drill must be carefully aligned with the workpiece (Figure 9) and this alignment must be maintained throughout the drilling operation. Care must be taken not to lose control of the portable drill and allow it to be wrenched from the operator's hands. The larger portable drills (Figure 10) can be very dangerous if not held firmly by the operator.

Fig. 9 - Drilling with portable drill - Perforando con taladro portátil

If the cutting speed is fixed, the operator must learn to control the feed of the portable drill by applying sufficient pressure for the drill to cut, but not too much pressure as to cause overheating of the twist drill or stalling of the portable drill motor.

When metal is to be drilled with the portable drill, the workpiece must be prepared by locating the center position of the potential hole and marking the location with a center punch. When a large drill is to be used, it will be necessary first to drill a pilot hole slightly larger in diameter than the thickness of the larger drill's web, which will allow for the drag caused by the larger drill's chisel edge (Figure 11).

Fig. 11 - Drilling a pilot hole for a larger drill - Perforando un agujero piloto para una mecha mas grande.

Portable pneumatic drills require special attention to lubricate their internal moving parts. Each drill may be made slightly different, so refer to the pertinent lubrication order or manufacturer's instruction manual before drilling.

For drilling by hand, the workpiece must be mounted securely. Thin workpieces should be backed up with a thicker piece of wood or metal to prevent the drill from snagging in the workpiece. Do not attempt to hold any workpiece by hand or serious injury could result.

Select a twist drill of the proper size for the hole to be drilled. Ensure that the twist drill selected has the right type of shank for the type of chuck mounted on the portable drill.

Taper shank drills cannot be mounted in a drill with a geared chuck. Check each twist drill for sharp cutting edges prior to use.

After securing the twist drill in the proper chuck, connect the portable drill to its power source. Position the portable drill perpendicular to the workpiece and center the chisel point of the drill in the center-punched hole of the workpiece.

Apply firm but not too heavy pressure upon the portable drill, pull the trigger or throttle button to start the drill.

Apply a few drops of cutting oil to the twist drill and hole (Figure 3-12) to improve the cutting action and prevent overheating of the twist drill. For long drilling operations, stop the drill and allow it to cool; then apply additional cutting oil to the drilling area. The lock button can be engaged for lengthy cutting operations.

Continue drilling the hole while applying enough pressure to produce a clean chip, but not so much pressure as to cause the motor to strain or the drill to bind. The drill must be held firmly at all times to prevent the drill from being wrenched from the hands of the operator if the flutes of the drill should snag on a metal burr in the hole.

As the twist drill nears the back wall of the workpiece, release the lock button so that the drill can be stopped immediately if required. Decrease the feed pressure as the drill breaks through, and cautiously feed the drill through the wall of the workpiece. If the drill should snag on a burr, stop drilling immediately and withdraw from the hole. Carefully feed the drill back into the hole while the drill is turning to cut through the burr.

When a portable drill is mounted to a vertical stand, the operating procedure is identical to that used for the upright drilling machine. Use the lock button while drilling and use the hand lever to drill to the required depth.

Portable drilling operations can be difficult to an inexperienced operator. It is difficult to keep the twist drill perpendicular to the workpiece during drilling, and it is hard to drill to a desired depth accurately. If help is available, use the buddy system to keep the drill aligned while drilling. To drill to depth, mark the twist drill with a light colored marking pen or a strip of tape and keep a close watch on the drill as it cuts. Another way to drill to depth accurately using the portable drill is to use a jig, such as a piece of metal pipe or tubing cut to length, to indicate when the drill has reached the desired depth.

Fig. 12 - Drilling lubrication, correct and incorrect - Lubricación de perforación, correcta e incorrecta.

OPERACIONES DE PERFORACIÓN

La operación de los taladros eléctricos y neumáticos portátiles difiere de los procedimientos de funcionamiento recomendados para una perforadora vertical. El taladro portátil es soportado a mano para la mayoría de las operaciones, y la velocidad de corte del taladro es fija o dependiente del control del operador. Cuando se soporta a mano, el taladro debe alinearse cuidadosamente con la pieza de trabajo (figura 9) y esta alineación debe mantenerse a lo largo de la operación de perforación. Se debe tener cuidado de no perder el control del taladro portátil para no permitir que se tuerza en las manos del operador. Los taladros portátiles más grandes (figra 10) pueden ser muy peligrosos si no se sostienen firmemente por el operador.

Fig. 10 - Drilling with a large portable drill - Perforando con un taladro de gran tamaño

Si la velocidad del corte es fija, el operador debe aprender a controlar la alimentación del taladro portátil aplicando la suficiente presión para que el taladro corte, pero no demasiada presión que cause un recalentamiento del taladro de mecha helicoidal o el atasco del motor portátil del taladro.

Cuando el metal debe ser perforado con el taladro portátil, la pieza de trabajo debe ser preparada ubicando la posición central del agujero en cuestión y marcando la localización con un punzón central. Cuando un taladro grande debe ser utilizado, será necesario primero perforar un agujero piloto levemente más grande en diámetro que el grueso del filo de mecha más grande, que permitirá que se produzca la fricción causada por el borde biselado de la broca más grande (figura 11).

Los taladros neumáticos portátiles requieren especial atención para lubricar sus piezas móviles internas. Cada taladro puede hacerse ligeramente diferente, por lo tanto refiérase a la orden correspondiente de instrucciones o al manual de lubricación del fabricante antes de perforar.

Para perforar a mano, el objeto se debe montar con seguridad. Las piezas de trabajo finas se deben sostener con un pedazo más grueso de madera o de metal para evitar el desrebabado de taladro en el objeto. No intente sostener ningún objeto a mano o una lesión seria podría resultar.

Seleccione un taladro de broca helicoidal del tamaño apropiado para que el agujero sea perforado. Asegúrese de que el taladro seleccionado tenga el tipo correcto de espiga para el tipo de mandril montado en el taladro portátil.

Los taladros de espiga de forma cónica no se pueden montar en un taladro con un mandril de engranajes. Compruebe el filo de cada mecha helicoidal antes de su uso.

Después de asegurar la mecha helicoidal adentro del mandril apropiado, conecte el taladro portátil a su fuente de energía. Coloque el taladro portátil perpendicular al objeto de trabajo y centre el punto biselado de la mecha en el agujero de centrado perforado en el objeto. Aplique una presión firme pero no excesiva sobre el taladro portátil, tire del botón del disparador o del botón de traba para encender el taladro.

Aplique algunas gotas de lubricante para cuchillas a la mecha helicoidal y al agujero (figura 3-12) para mejorar la acción de corte y para prevenir el recalentamiento de la mecha. Para las operaciones largas de perforación, pare el taladro y permita que se enfríe; luego aplique lubricante para cuchillas adicional al área de la perforación. El botón de bloqueo se puede accionar para operaciones muy largas de corte.

Continúe perforando el agujero mientras que aplica bastante presión para producir una viruta limpia, pero no tanta presión para hacer que el motor se sobrecargue o que la mecha se doble. El taladro se debe mantener firmemente siempre, para evitar que el mismo se desprenda de las manos del operador si las ranuras de la mecha se encastraran en las rebabas del metal en el agujero.

A medida que la mecha helicoidal se acerca a la pared trasera del objeto de trabajo, libere el botón de bloqueo para poder parar el taladro inmediatamente si es necesario. Disminuya la presión del proceso de taladrado a medida que la mecha pasa, y accione cautelosamente el taladro a través de la pared del objeto. Si el taladro se encastra en las rebabas, pare el perforar inmediatamente y retírese del agujero. Cuidadosamente inicie el proceso de taladrado nuevamente dentro del agujero mientras que la mecha está girando para cortar a través de las rebabas.

Cuando un taladro portátil se monta sobre un soporte vertical, el procedimiento de funcionamiento es idéntico a aquel usado para la perforadora vertical. Utilice el botón de bloqueo mientras que perfora y utilice la palanca de mano para perforar a la profundidad requerida.

Las operaciones de perforación con taladro portátil pueden ser difíciles para un operador inexperto. Es difícil mantener la mecha helicoidal perpendicular al objeto durante la perforación, y es difícil perforar a una profundidad deseada con precisión. Si la ayuda está disponible, recurra a un ayudante para mantener el taladro alineado mientras se perfora. Para perforar en profundidad, marque la mecha helicoidal con un marcador de color claro o un trozo de cinta y mantenga estrecha vigilancia al taladro a medida que corta. Otra manera de perforar en profundidad con precisión usando un taladro portátil es utilizar una plantilla, tal como un pedazo de cañería o de tubería de metal cortada a medida, para indicar cuando el taladro ha alcanzado la profundidad deseada.