A beginner's guide to power drills

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All power-driven tools, but especially the power drill, make work easier for the woodworker.

Most drills are pretty much the same, regardless of size and make. They have a motor, trigger switch and chuck to hold the bit. The jaws within the chuck hold the bit in place to prevent it from slipping once locked. The jaws are locked with the aid of a chuck key, which you turn clockwise to lock, and anti-clockwise to unlock.

Most drills have a pistol-style hand grip with a trigger switch that can be locked for safety. Some are supplied with a second adjustable hand grip for increased control, which is located directly behind the chuck at the front of the tool. The body of the drill houses the motor, while the front holds the gearbox that regulates the speed and functions.

BUYING A DRILL

Speed
Battery drills are handy, but not as powerful as power drills. Also, a drill is more useful if it has more than one speed: low speed for metal or masonry work, and a higher speed for timber.

Chuck size
The chuck size refers to the size of a drill bit shank that fits in the drill. Generally, the more powerful the drill, the bigger the chuck. For example, a 500-watt motor could have a 10mm chuck, while a 700-watt motor may sport a 13mm chuck. Either of these are suitable to the average woodworker.

Impact drills or hammer drills
These are best for masonry. Unlike normal rotary drills, where the bit remains locked in the chuck and rotates, the bit in these drills vibrates in and out while rotating. The effectiveness of this action relies on the force you apply to the drill. This action may be disengaged to drill normally.

Accessories
Drills may have many accessories that can convert them to other uses, such as disc sanders, buffers, grinding wheels and even jigsaws. A vertical drill stand drills holes straight and to a required depth.

OPERATING THE DRILL
Select the appropriate bit for the job. Never use auger bits with a lead screw as they will jam and/or overload the motor. Instead, select spade bits that can be used on high speed. Always use tungsten carbide bits for masonry - they are made to withstand the pressure required.

Place your selected bit in the chuck. Ensure it is in the centre and turn the chuck key clockwise until the jaws have tightened on the drill shank, then remove the chuck key (note that some drills have keyless chucks).

Select the correct speed for the bit and job. Smaller bits require a higher speed than a bigger bit. Remember: the harder the material, the slower the speed. When drilling holes that are more than 8mm in diameter, use a drill with a side handle for greater control and to help prevent injury should the bit jam.

Secure your work in a vice or clamp and maintain a firm grip while you are drilling. Keep the drill at the required angle. Changing the angle while drilling may break the bit or make an irregular hole.

DRILLING HINTS
Use a punch to create a starting target point to prevent twist drill bits wandering.

Keep the drill running until it is removed from the hole - this will help clean out any waste. Move the drill back and forth while drilling masonry or hardwood to help clear the hole and drill bit.

When drilling ceramic tiles, place masking tape over the area you are going to drill for grip and to prevent the tool wandering. Never use the impact or hammer action on tiles or they will crack.

If you are drilling all the way through a piece of timber, it's a good idea to clamp a block of scrap timber to the back of the job. This will help prevent the back splitting when the drill breaks through the other side.

Safety
Portable power tools are dangerous and should be used with extreme care. Follow these safety guidelines whenever you use power tools:

• Read the manufacturer's handbook, particularly anything regarding safety and correct operation.

• Never use faulty tools.

• Never use tools with faulty or frayed leads.

• Never lift tools by the lead or disconnect them by pulling the lead.

• Keep leads away from cutting blades and drill bits.

• Disconnect the power supply before adjusting the tool.

• Allow tools to reach full speed before working with them.

• Never use tools in wet conditions.

• Avoid dropping tools.

• Never use tools for any purpose that they were not designed for.

• Wear appropriate safety clothing and equipment.

MAKING A DEPTH GAUGE
Use a piece of dowel. Once the drill bit is inserted in the drill, measure the length of the bit and subtract the depth of the hole. Cut a piece of dowel to this length, place it in a vice and bore an 8mm hole right through. Remove the bulk of the timber at one end, making it look like a pencil with the drill being the lead.

Source: Basic Carpentry Techniques (Murdoch Books)