Lesson plan
Hex key
A hex key (also hex wrench, Allen key, Allen wrench) is a simple driver for bolts or screws that have heads with internal hexagonal recesses (sockets). Hex keys are generally formed from a single rod of hard hexagonal steel, having blunt ends that fit snugly into similarly shaped screw sockets. The rod is bent to 90°, forming two arms of unequal length resembling an "L" shape. The tool is usually held and twisted by its long arm, creating a relatively large torque at the tip of the short arm; it can also be held by its short arm to access screws in difficult-to-reach locations and to turn screws faster at the expense of torque. Hex keys are designated with a socket size and are manufactured with tight tolerances. As such, they are usually sold in kits that include a variety of sizes. Key length typically increases with size but not necessarily proportionally so. Variants on this design have the short end inserted in a transverse handle, which can contain multiple keys of varying sizes that can be folded into the handle when not in use. While often used generically, the "Allen" name is a registered trademark (circa 1910) of the Allen Manufacturing Company (now Apex Tool Group) of Hartford, Connecticut.
Article summary
A hex key (also hex wrench, Allen key, Allen wrench) is a simple driver for bolts or screws that have heads with internal hexagonal recesses (sockets). Hex keys are generally formed from a single rod of hard hexagonal steel, having blunt ends that fit snugly into similarly shaped screw sockets. The rod is bent to 90°, forming two arms of unequal length resembling an "L" shape. The tool is usually held and twisted by its long arm, creating a relatively large torque at the tip of the short arm; it can also be held by its short arm to access screws in difficult-to-reach locations and to turn screws faster at the expense of torque. Hex keys are designated with a socket size and are manufactured with tight tolerances. As such, they are usually sold in kits that include a variety of sizes. Key length typically increases with size but not necessarily proportionally so. Variants on this design have the short end inserted in a transverse handle, which can contain multiple keys of varying sizes that can be folded into the handle when not in use. While often used generically, the "Allen" name is a registered trademark (circa 1910) of the Allen Manufacturing Company (now Apex Tool Group) of Hartford, Connecticut.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.