An Idiot's Guide to Power Tools (Drills, Sanders, & Saws), Corded & Cordless
A Beginner's Guide to Power Tools
Thinking of buying a power tool as a gift for your nearest and dearest? Or maybe you want to make light work of DIY? This article is a beginner's guide for those of you who don't know your cordless drill from your elbow. It gives a basic explanation of what each tool is for, its capabilities, and tips on what to buy.
Which Tool Is Right for the Job?
Basic Tools Covered Here
- Corded Power Drill
- Cordless Drill
- Circular Saw
- Reciprocating Saw
- Miter Saw
- Angle/Hand Grinder
- Metal Cutoff Saw
- SDS Percussion Drill
- Rotary Tool (Dremel)
Corded Power Drill
What's it for: A corded power drill is used for drilling holes in metal, plastics, wood, brick, stone, concrete, glass, and tiles. Various types and lengths of drill bits are available depending on the material being drilled; HSS (High Speed Steel) bits for metal, flat bits for wood, and masonry bits for concrete.
How it works: The bit is held in a clamping device on the end of the drill shaft called a chuck. Some drills come with chucks which are keyless and can be hand-tightened, others are fitted with chucks which need to be tightened with a chuck key. This allows the drill bit to be tightened more securely and large bits are less likely to slip, but keyless hand-tightening chucks are more convenient. Most DIY model drills will have a 1/2 inch (13mm) chuck which can accommodate drills up to this diameter, but 5/8 inch (16mm) chucks are also available. These drills range in power from about 500 to 800 watt. 650 to 700 watt provides adequate power for most jobs.
If you need to drill holes in awkward spots, you can get a right angled chuck adapter which fits into the chuck of the drill. Alternatively flexible drives are available.
Things to consider: Drills may have a fixed speed setting, 2 speed settings, or variable speed depending on how hard you squeeze the trigger. Variable speed is most convenient as it allows a drill hole to be started easier without the bit moving all over the place. Also lower speeds should be used with larger diameter bits to avoid overheating the bit due to friction.
Bosch PSB 750 Corded Drill
Although green Bosch products are their DIY line (blue Bosch is for pro users), I've used the 650 model of this drill (650 watt) for over 15 years for heavy DIY use, and it's still going strong. These drills from Bosch are well built, reliable and highly recommended. This model is rated at 750 watt.
Various Types of Chucks
What it's good for: A cordless drill, like any other cordless power tool, has the convenience of freedom from a power cord. This means no cables to trip over or moving extension leads around to provide slack in the cord. A cordless drill can also be used in awkward places, up ladders and on roofs without the inconvenience of the power flex catching in everything. Another advantage is that a cordless drill is better balanced and easier to use with one hand, especially for driving screws. Corded drills tend to be top-heavy and difficult to use with one hand.
How it works: Cordless drills usually have either a 3/8 inch (10mm) or 1/2 inch (13mm) hand-tightening chuck. Combi drills have a hammer action function which facilitates drilling of holes in masonry. Cordless drills are available with battery voltages from 10.8 to 36 volts. Higher voltage means more power and torque for drilling larger diameter holes. However, the downside of higher voltages is a heavier drill. 14.4 or 18v is a good compromise.
Cordless drills have various torque settings. This ensures that the chuck will slip when a preset twisting force or torque has been applied to a screw, preventing the screw from being over-driven into timber.
Things to consider: Just like some corded drills, cordless drills may have a low and high speed setting. A gearbox sets the speed and choosing the lower speed setting results in more torque being available for drilling larger diameter holes. If you need to use the drill for driving TEK screws (self-drilling screws for fastening metal cladding to metal or timber), aim for a model with a max torque of at least 55 NM to cope with tough timber.
If you buy a cordless drill, buy one with two batteries so that you can have one battery on charge while using the other. Batteries are quite expensive when bought separately.
The capacity of a cordless drill battery is measured in amp-hours or AH. Higher amp-hour capacity batteries will give longer use between charges. Lithium ion rechargeable batteries are becoming more common in cordless drills and this technology doesn't suffer from the memory effect associated with NiCd batteries. Also lithium batteries have a higher energy storage density than NiCd or NiMh. This results in a lighter battery for a given capacity. Another advantage of lithium batteries is that they hold their charge much longer, so a tool is always ready for use.
The latest trend in cordless tools is the use of brushless motors. This supposedly results in more power plus no need to replace brushes. Brushless tools are more expensive, so you may get a better deal on a cordless drill with brushes which have somewhat dropped in price.
SDS Percussion Drill
What it's for: The acronym SDS originates from the German steck, dreh, sitz, meaning "insert, twist, fit" and the system was developed by Bosch in the mid '70s.
How it works: An SDS drill and drill bit has several advantages. Firstly, removing and inserting the bit is easy. The shank of the bit is simply pushed into the chuck and a spring loaded mechanism latches into slots in the shank, holding it in place. To remove the bit, a sleeve on the chuck is pulled back retracting the spring mechanism, and this allows the bit to be pulled out of the chuck. The second advantage is that the wedges which slide into the grooves in the shank prevent the bit from slipping and rotating in the chuck, which can happen with a conventional chuck if it isn't adequately tightened. Thirdly, since there isn't a heavy chuck to accelerate during impact drilling, this ensures that holes are drilled more effectively since the drill reaches a higher speed and has more energy. The percussion mechanism is also pneumatically based and this gives extra energy for hammer drilling in masonry compared to a normal drill which just uses a plate with ridges on it to generate the hammering effect.
Things to consider: SDS drills can be set to rotation mode only, for drilling materials other than masonry, or rotation and hammer mode for drilling masonry. On some models, the drill can also be set to hammer mode only without rotation, for light chiseling. These drills range in power from about 500 to 1500 watt but are usually geared to have relatively low speed and high torque. A mechanical or electronic torque limiting system which allows the chuck to slip when the bit gets stuck is often (but not always) incorporated. A typical scenario is that the bit gets caught on a piece of rebar in a wall, and the power drill tries to keep going. This can wrench your arm (been there, done that!) or force the drill out of your hands if it is not held securely. The torque limiting system is similar to that on a cordless drill and allows the motor of the drill to turn while the bit stays stuck. Even so, this is why it can be dangerous to use a drill when on a ladder as it is possible to be knocked off balance.
Conventional hand-tightening keyless chucks and keyed chucks are available for use with an SDS drill. These have an SDS shank so that they can be pushed into the SDS chuck of the drill. This enables non-SDS conventional drill bits to be used.
What it's for: Jigsaws can be used to cut wood, metal, plastic, and other materials. Different types of blades are available to suit the material being cut. Since the blades used in a jigsaw are slim and narrow, this allows curved profiles such as circles to be cut in sheet material. Jigsaws are normally used for cutting timber up to about 40 mm thick (approx. 1 1/2 inch). Long blades can be used in a jigsaw and manufacturers quote maximum cutting capacity up to 4 inches (this seems a bit overly optimistic!).
Things to consider: Variable speed on the trigger is a useful feature on a jigsaw when commencing or finishing a cut. Some saws have a separate speed control, which is a real pain! While a jigsaw gives reasonably good results with thinner timber, the outcome can be variable if thicker stuff needs to be cut. Because the blade can flex if the side pressure is put on the saw, this can produce a cut which is not perfectly square. A circular gives a much better cut and is a faster, more accurate solution for making long, straight cuts in thick timber.
What it's for: A circular saw is a high powered saw (1000 watt to 1800 watt) with a 7 1/4 inch (184 mm) diameter blade or greater, able to rapidly cut through timber up to 3 1/2 inches (90mm) in thickness, and is an essential power tool for cutting sheets of timber. A circular saw will give a more "square" cut than a jigsaw because the blade is more rigid. The large teeth on the blade also make the cutting of boards much quicker than with a jigsaw which is more suitable for short cuts or curved cuts in thinner material. An adjustable rip fence can be attached to the saw, and this acts as a guide to allow boards to be trimmed to size. Blades which have a relatively small number of teeth give a fast but rougher cut. Blades which have a greater number of smaller teeth cut slower, but result in a finer cut.
Things to consider: If you intend to use a circular saw a lot, it's worth buying a pro tool. Checkout my review of the Hitachi C7SB2 circular saw. I bought one of these as a replacement for a DIY model. This is an excellent machine with a power rating of 1700 watt and a cutting capacity of 2 3/8" or 60 mm, and I highly recommend it.
Hitachi C7SB2 Circular Saw from Amazon
What it's for: A reciprocating saw or rip saw is a useful tool for cutting timber, plastic and metal. The tool is similar to a jigsaw but usually higher powered and the blades are longer, up to 8 inches (200mm). The tool is also long and slim and can be held with two hands to give better control. It is useful therefore for cutting lengths of timber in situ and flush to surfaces, floorboards, plastic piping, metal bar, and for demolition work.
Things to consider: When buying a saw, don't go for anything less than 800 watt as the machine will struggle when cutting thicker sections of timber. Variable speed is also a useful feature.
What it's for: Sanders are used for smoothing down timber, removing paint, and sanding metal. There are two major types: belt sanders and orbital sanders.
- Belt sander: This has a continuous looped belt of sandpaper which is driven by the motor. The belts are replaceable and available in various grit sizes, coarse for initial sanding and fine for finishing. Belt sanders remove material quickly as the revolving belt tends to throw off sawdust and doesn't become clogged unlike an orbital sander, however it is difficult to sand into a corner because of the curved rollers. The belt is normally 2, 3 or 4 inches wide (50, 75 or 100mm).
- Orbital sander: This uses sheets of sandpaper and the sheets are driven in a sort of circular motion when the sander is applied to the surface. The sheets tend to clog more than on an orbital sander. An orbital sander can sand right into corners because of the rectangular shape of the sole plate. Various versions of these are available including palm sanders which can be used with one hand in tight spots because of the small size and shape of the sandpaper used.
- Sanding pad for angle grinder: A rubber sanding pad is available as an accessory for angle grinders. These are useful for sanding profiled surfaces and also for getting into spots which would be inaccessible to belt or orbital sanders.
Miter (Mitre) Saw
What it's for: A miter or chop saw is used for cutting lengths of timber up to 9 x 2 inches. It is basically like a circular saw but the blade has a larger diameter, 8, 10, or 12 inches (200 or 250mm), and the cutting head/arm carrying the saw blade and motor is hinged at the back allowing the saw to be brought down on to a length of wood to cut it. This produces an accurate square 90 degree cut, essential for construction. A basic type miter saw is adjustable so that miter (angled and less than 90) cuts can be made. Compound miter saws enable miter cuts, beveled cuts or a combination of both to be made. A 10 inch sliding compound miter saw is a wise investment for the serious DIYer. The slide action allows lumber to be cut (up to 9 x 2). For square cuts on light timber such as dado rail, picture frame, an 8 inch non sliding miter saw is sufficient.
Things to consider: Never use a blunt blade in a circular saw or miter saw. Blunt blades can catch or snag in timber which can potentially cause an accident.
What it's for: An angle or hand grinder is an invaluable tool for cutting metal, plastic, roof sheeting, masonry (stone, bricks, concrete), and tiles. You can also use it to grind these materials. Both sheet material and lengths can be cut.
How it works: The tool uses a disk spun at high RPM to perform the cutting action. For cutting metal, consumable disks made from abrasive material are used. These are available in sizes from 4 to 9 inches in diameter to suit the specific grinder. In order to cut stone, concrete and tiles, either abrasive or diamond disks can be used. Diamond disks have a longer lifespan, but are more expensive. Angle grinders can come in handy for cutting up stuff for disposal in your trash (like metal chairs and tables). Make sure you grind off the sharp edges.
Things to consider: Several accessories are available for angle grinders including sanding pads and wire brushes which can be used for removing rust and paint.
Rotary Tool (Dremel)
What it's for: Generically called "rotary tools" but more commonly known as "Dremels" (even though other companies make them too!) these tools are the DIY equivalent of die grinders. Die grinders are employed by toolmakers in industry for shaping the dies and moulds used in factories for metal processes such as casting and pressing. With a rotary tool you can grind, sand, carve, cut, slot, router, hollow, engrave, sharpen and debur (remove ragged edges from material).
How it works: Rotary tools are like power drills but more slender, designed for one hand use. They have an electric motor which runs at very high speed, up to 35,000 RPM, and this spins a chuck type clamp which holds various sized collets or sleeves. These sleeves can hold a variety of types of accessories.
Here's a list of the accessories available:
- Grinding stones are available in all shapes and sizes and can be used for general grinding, material removal, hole enlarging, sharpening, de-burring, and removing sharp edges from metal.
- Sanding drums, discs, and flapwheels can be used for sanding and smoothing wood, metal, and plastic.
- Polishing accessories are small buffs which can be used with metal polish or polishing compound for giving a fine polish to metal.
- Toothed metal cutting disks like miniature circular saw disks can be used for cutting wood or plastic.
- Diamond coated or abrasive cut-off wheels are available for cutting metal.
- Soft plastic and wire brushes are another accessory, useful for cleaning surfaces.
- High speed cutters of various sizes and shapes can be used for grinding, carving and hollowing materials such soft metals, plastic, and wood.
- Tungsten carbide cutters do the same as standard cutters but can be used on hardened steel, stainless steel, cast iron, and ceramics.
- Diamond points can be used for fine detail work, cutting, carving, engraving, and finishing of glass, ceramic, and other hard materials.
You can also use a rotary drill with small drill bits.
Things to consider: The accessories for rotary tools are usually not much larger than 1 inch so unlike an angle grinder, the tool is geared towards small scale work such as model and jewelry making. However the tool can come in very useful in the home workshop where a larger tool would be too cumbersome.
Metal Cutoff Saw
What it's for: A metal cutoff saw is like a miter saw but normally used to make 90 degree and miter cuts in metal bar and hollow metal sections.
How it works: An abrasive disk similar to the type used on angle grinders but with a diameter of 14 inches performs the cutting action.
Things to consider: Although probably the least likely power tool to be used by the average DIYer, a cutoff saw, like its timber counterpart, enables accurate angled cuts to be made, which is essential when constructing metal frames, gates, etc.
110 or 220 Volts?
The voltage supply differs from country to country. It can either be nominally 120 volts or 240 volts (with a 10 % variation). In the U.S. both voltages are available, 240 being used for higher powered appliances. In some countries however, the supply voltage is 230 to 240 volts, so 120 volts tools are available which lessen the risk of electrocution in the event of shock. These are mandatory on construction sites but can also be used in the home. They can either be powered by a generator with a 120 volt output, or alternatively transformers are available to step down the voltage from 240 to 120 volts. These step down transformers also isolate the 120 volt supply from the mains. This reduces the risk of shock if for instance contact is made with a damaged power cord.
Buying Power Tools
If you are going to be giving a tool a lot of use, it makes sense to buy a professional model. It will last longer since it will usually be built more sturdily and the internal components will be more heavy duty and durable. Motor windings are normally wound using heavier gage wire, and armatures are often covered to prevent particles getting sucked into the motor and abrading the winding insulation. Also parts will be easier to source. If a tool is only going to get occasional use, a DIY model should be fine. Most if not all of the tools described above are available in cordless versions.
What to Look for in a Tool
Recommended Basic Specs.
Combi with hammer action, 18 volt, 10 mm chuck
650 watt, keyed 13 mm chuck
600 watt, variable speed on trigger
600 watt, 75 mm wide belt
650 watt, variable speed if possible
254 mm blade, sliding compound
800 watt, variable speed