Before randomly picking a drill bit to insert into your cordless drill and drilling a hole, one must carefully select the correct drill bit size before doing so. Choosing the correct drill bit size can be confusing depending on where you live and where you purchased your drill.
Drill bit sizes in the United States of America are still sized according to fractions of an inch. These drill bit sizes start with the smallest drill bit size – namely 1/64 of an inch to the largest being 1 inch in diameter. As the size increments are increased in 1/64 of an inch the difference in size of smaller drill bits are very large, which can cause slight irregularities in size and could in turn affect the end result, especially when the size of the drilled hole must be precise.
In most other countries outside of the US, the metric system of measurement is widely used to measure drill bit sizes. This system of measuring drill bit sizes was introduced by the British in 1959. The diameter of drill bits are measured in standard metric lengths, making selecting the correct drill bit size to use for a particular project much easier. The drill bit sizes increase in increments of 0.5mm, however smaller drill bits may come in increments of 0.1mm for precision drilling.
Drill bits are commonly purchased in sets that have a variety of sizes from smallest to largest in diameter. Drill bits are placed in these sets according to their sizes. Drill bit sizes are usually indicated on the drill bit itself on the end that is inserted into the drill as well as in the set making the selection of the correct drill bit size for your project much easier. Special drill bit sizes needed for specialised projects can be purchased at hardware stores.