Allen keys are the term given to a simple hand tool from the spanner and socket family. These tools are used to tighten and loosen hexagonal bolts and other types of compatible fasteners. They are most usually found in the form of one piece of steel that has been formed into the shape of a small L, though there are variations of this available.
Allen keys are very versatile driving/fastening tools and thus in wide use across a range of applications and product categories. Despite their ubiquity there are a number of mistakes that people should avoid when buying Allen keys.
Allen keys and hex keys
The terminology surrounding Allen keys can be confusing to newcomers, as the term Allen keys seems to be used almost interchangeably with another name – hex keys. So what are hex keys and do you need to buy one of those as well?
Hex keys are actually another name for Allen keys. The terms are conflated because it was a William G Allen who patented the cold drawing process for the manufacture of hex socket screw sets and the wrenches to turn those screws made him famous. Allen keys are a registered trademark, but Allen keys has become such common terminology that hex keys from other manufacturers are still sometimes referred to as Allen keys.
Make sure you choose the right type
Allen keys are bought in sets that include a wide range of sizes intended to fit different sockets. However Allen keys can be bought in both imperial and metric sizes, depending on the bolts or screws that are being utilised, with most sets providing sizes that range from 1-10mm.
Anyone who intends to purchase just one set of Allen keys should make sure they buy the metric version rather than the imperial one, particularly if they live outside of the United States. Most manufacturers outside the US use the metric system, so buying imperial sizes would result in confusion as they are not interchangeable.
Choose the right shape
Once you have made the decision what type of Allen keys to buy you will then have to narrow your choices by shape. There are some Allen keys that will be flat at either end, while some others come with a ball end that looks like it sounds.
The same job is done by both of these types of keys, though the latter has greater versatility on account of the rounded shape being more manoeuvrable when in tight spaces. The ball end can start off a screw that is hard to reach and then the flat end can finish the task.
Choose the right size
Even if you have purchased the appropriate metric sets there are still different sizes of Allen keys. The sizes will be labelled on the packets but if they have been lost or misplaced the size can still be identified via the tool itself, which normally has the size printed on the side.
Store them properly
A mistake that is easy to avoid when you buy Allen keys is storing them improperly, which can result in rust. To make sure this does not happen, store them in a clean, dry place such as a toolbox and wipe and lubricate them after every use.