An Allen key, also known as a hex key or hex wrench, is a small, L-shaped tool used to drive bolts and screws with hexagonal (six-sided) sockets in their heads.
🔧 At a Glance: Allen Key
| Feature | Description |
|---|---|
| Shape | L-shaped metal rod with a hexagonal cross-section |
| Material | Usually made of hardened steel |
| Other names | Hex key, Hex wrench |
| Sizes | Comes in metric (mm) and imperial (inch) sizes |
🧠 Why is it useful?
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Fits into recessed hex-shaped holes in screws and bolts.
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Great for tight spaces due to its L-shape.
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The long arm provides leverage; the short arm fits into tight spots.
🔩 Where is it used?
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Assembling furniture (like IKEA kits)
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Bicycles and motorbikes
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Machinery and appliances
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3D printers, electronics, tools
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Any device with hex socket screws
⚙️ How it works:
The hex shape provides six contact points, giving good grip and reducing the chance of slipping or stripping the screw.
You insert the Allen key into the screw and turn — clockwise to tighten, counterclockwise to loosen.
🧪 Fun Fact:
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Invented in the early 20th century by the Allen Manufacturing Company, which is where the name comes from.
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Some Allen keys are folding sets like a Swiss Army knife; others come as individual pieces or in T-handle form for better grip.