Everyone knows a little about drill bits and that you put them into your electric drill to drill a hole, but, do you really know when to use which bits for certain holes and applications that you want to drill?
There are 4 basic drill bits that the can be used for everyday use and then there are specialized drill bits which are usually expensive and not worth buying unless you are going to use it on a regular basis.
Your 4 basic drill bits are Masonry, Wood, Twist and Tile. The other drill bits that are not so commonly used everyday by everyone one are Countersink, Spade, Hole Saw, Forstner and Wood Auger.
These bits are most commonly used in the home. The Masonry bit is generally silver in color and the tip looks spade like and the tip is normally painted red. They are used for drilling into brick, block, stone, quarry tiles or concrete. The cutting tip is made from tungsten carbide bonded to a spiraled steel shaft. These bits are used with a hammer action drill with or without speed variation, depending on what you are drilling into. Beware of cheap Masonry bits as they will tend to break, shatter or even melt from too much force or heat that they generate. It is good to make sure that when you buy Masonry bits that you talk to your hardware dealer and get the best option on Masonry bits available.
Use a variable speed drill when drilling into harder surfaces. The harder the surface, the slower you set your drill speed. This will prevent the bit and the drill from being damaged and always make sure that when drilling with Masonry bits that you drill is set to the hammer action. This moves the bit back and forth while drilling in order to pound the surface to gain more depth without any damage.
You can use a Masonry drill bit to drill into ceramic tiles. Should you do this, make sure that the hammer switch is in the off position and drill into the tile at a slower speed to prevent the tile from cracking.
These are used for drilling into wood and some plastics. The bit is normally black in color and the tip of the bit has a raised spur or sharp point. This is used, before drilling, to place the point exactly where you want to drill the hole and using a bit of force to push the point into the wood to stabilize the bit before drilling. This will also ensure, while drilling, that your bit goes straight into the wood without running around and damaging the wood. You can use a variable speed drill for these bits but make sure the drill is not on the hammer position else you will damage the wood and the tip of the drill bit.
You get two common types of Twist drill bits the more common and cheaper one is called a High Speed Steel (HSS) bit. This is suitable for drilling most types of material such as metal, plastics, timber and similar materials.
This type of bit is most commonly used by most people. The bit is normally black in color and the front edges cut the material and the spirals along the length remove the debris from the hole and tend to keep the bit straight.
The more expensive bit is a Carbon Steel Bit which is specially ground for drilling very hard or tough wood and should never be used for drilling into metals at all.
This bit has a ground tungsten carbide tip and is used for drilling ceramic tiles and glass. The head is usually black in color. It is best to use a variable speed power drill for this bit and generally at a slow speed so that you will not crack or break the glass or tile that you are drilling into.
When drilling into glass, it is best to use a lubricant such as turpentine or white spirit to keep the tip cool and prevent the glass from cracking or breaking. Also, drill at a slow speed into glass.
When drilling into a ceramic tile, also drill at a slower speed but no liquid is needed to keep the tip cool.
The bit is conical shaped and normally silver in color. This is not really a true drill bit but is used to form a recess for the heads of countersunk screws. These are designed for use on soft materials such as timber and plastics but not for metals on masonry. Never countersink an existing hole as the bit will tend to wobble and damage the hole or wood and will leave ugly rough edges. Place the point of the countersink where you want the hole to be and then proceed with the drilling.
The bit has an extended sharp point at the tip and a wing on either side below the long tip and is normally black or silver in color. The wings edges are very sharp as well as the tip, so be careful when using this tool.
The Spade Drill Bit is only used on wood and is used to drill large flat holes with a countersink in the centre for then drilling a hole through the wood for screws or bolts. Never use this to drill into and existing hole as the bit will not be steady and thus you can damage the bit and the wood and in the process injure yourself as well.
This bit has an extended Twist Bit in the centre with a round saw blade around it. This works very much the same way that a normal wood saw would work except that it is round. The bit is used for wood and some plastics and sometimes, you get a special bit that you can use for masonry but they are generally quite expensive.
The Hole Saw Bit is used for drilling large diameter holes into wood or plastics where you the need to insert something through the hole. You get various sizes, just talk to your local hardware store and let them know exactly what size you are looking for.
This is a very oddly shaped bit with only a short head and large teeth that are positioned at a slope, very much like a broad bladed saw, only circular. This bit is used to form flat shallow holes which are used mainly on cupboard doors for placing the door hinges into it. When using this bit, ensure that your power drill is used with a drill stand in order to stabilize the bit as the bit has no point of its own to stabilize itself.
The bit looks almost like a big screw with deep edges. Generally this bit is used by a hand drill and not an electrical drill for better stability and accuracy and is ideal when drilling large-diameter, deep holes in wood or thick man-made boards. The single spur cuts and defines the edge of the hole while the chisel-like cutting edge removes the waste within the previously cut circle. The threaded centre bites into the wood and pulls the bit into the timber. This 'pulling' action means that the bit is really unsuitable for use in a power drill.