What are Hexagon and Torx Keys used for?
Hexagon and Torx keys are used for turning corresponding fasteners, such as in-hex bolts. These fasteners have advantages for certain applications.
When to use a Hexagon or a Torx Key?
As there are no external corners on an in-hex bolt head, they are less likely to catch on clothing. As hex keys fit into the head of an in-hex bolt instead of around it, as with a regular bolt, the bolt head does not need space around it for a socket or spanner to fit. This enables them to fit into recessed areas of a workpiece with minimal clearance.
Hex and Torx keys can also turn headless fasteners with the correspondingly sized female recess, such as a grub screw. A grub screw’s thread runs the entire length of the screw – there is no head projecting beyond the thread, so the screw is turned by the turning tool fitting into an indented shape in the top end. As grub screws have no head, they sit flush with whatever object they are securing.
Common examples of where hex keys are used include some bikes, cars, flat pack furniture and electronic equipment.
Why are Torx fasteners used instead of in-hex fasteners?
More torque (see below) can be applied with a Torx key and fastener than with many other fastener and turning tools such as hex keys and screwdriver bits. This is because of the greater number of contact points between the Torx key and the fastener, and the angle of these contact points being closer to 90 degrees than with other turning tool designs.
These factors reduce the risk of camming out and stripping the fastener head.
The extra torque factor associated with Torx is also why fasteners with smaller, lighter heads can be used where a specific torque setting is required. Torx fasteners have long been used in the aerospace and electronics industries and are increasingly common in the automotive and construction industries.
What is Torque?
Torque is a turning force. It can be calculated by multiplying the force applied by the distance along the length of the lever used to apply it. Torque can be calculated in either Newton meters (Nm) or pounds-feet (lb-ft).