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The Daily Insight

What is Allen key used for

Author

Lily Fisher

Published Apr 29, 2026

A hex key, also known as an Allen key is a simple tool used to drive bolts and screws with hexagonal sockets in their heads. From standard keys in chrome vanadium steel to extra-long with ballpoint heads in chrome molybdenum steel, there are a wide variety to choose from.

What is the purpose of Allen key?

An Allen key or Allen wrench is also known as Hex key. This is a small handheld tool used for turning bolts and screws which have hexagonal sockets.

Is an Allen key the same as an Allen wrench?

A hex key, also known as an Allen key or Allen wrench, is a small handheld tool that’s used for for driving bolts and screws with a hexagonal socket. They are available in many different sizes, though they all have the same hexagonal-shaped tip.

Why do technicians use Allen keys?

Why do some technicians use Allen keys instead of self-tapping screws to fasten joint? … To summarize, a hex key is a tool having a hexagonal socket that is used to drive nuts and screws. They are easier to use and less prone to strip than their Phillip’s head equivalent since they have six driving points.

What is the difference between Hex and Allen keys?

Some call it a hex key, others – an Allen wrench. … This article is aimed to help you figure out the difference between an Allen wrench and a hex key. The short answer is “there is no difference”. Really, these two names can be used interchangeably.

Why Allen keys are used to fasten joints?

There are many benefits for the use of the screws and Allen keys: They are economic and easier to produce. Their lever arch mechanisms allows you to apply increased tightening torque. The key does not risk to get out from screw.

Why are hex wrenches called Allen wrenches?

Originally named Allen Manufacturing Company, the business produced hexagonal set screws and wrenches to fasten them. The terms “Allen wrench” (American English) and “Allen key” (British English) are derived from the Allen brand name and refer to the generic product category “hex keys”.

Why do people use Allen screws?

Allen head screws can tightened to a higher torque than either a slot head screw or a cross head screw. They are readily available in high tensile versions. Allen head screws are often used in production line products as they can be easily power tightened to a preset torque.

How do I use Allen key?

Allen keys work like most other screwdrivers and wrenches but with a few nuances. You can use them by placing one of the ends inside a fastener with a hexagonal socket head and turning it. Turning the Allen key clockwise will tighten the fastener, whereas turning it counterclockwise will loosen or remove the fastener.

What is the L tool called?

So what is an Allen wrench you may ask? Alright, we’ll finally tell you. It’s the L-shaped tool that takes the form of a hexagonal key. Allen wrenches are used to fasten hex screws into wood, metal, and even plastic.

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What is socket ratchet?

A ratchet and socket combination (sometimes called a socket wrench) lets you turn a nut or bolt without repositioning the tool on the fastener — like you need to do with a wrench when there isn’t enough room to turn it in a full circle. This can make the work quicker.

How many sides does an Allen key have?

Allen Wrenches, also called hex keys, Allen keys or hex wrenches, are six-sided L-shaped wrenches designed to drive hexagon-shaped recessed holes. This makes hex keys the tool of choice for socket cap and socket set screws found in mechanical equipment, bicycles, engines, and assemble-it-yourself furniture.

Why do Allen keys have a ball end?

The ball end makes it easier to slide the key into the receiving slot. It allows you to reach at an offset 30 degree angle so that you can feel your way to the needed position much faster – great for blind or difficult areas to reach or if the bolt or screw is close to an obstruction on one side.

How do you remove Allen screws without Allen keys?

Sometimes you can use small types of flat headed screwdrivers as an allen wrench by putting the end in the socket so that the 2 edges of the screwdriver work as leverage in the hole to turn it. A wider socket on the bolt or nut, use a wider flathead screwdriver.

How many types of Allen keys are there?

14 Different Types of Allen Wrenches.

How do I know my Allen key size?

Most Allen wrenches have the size stamped clearly on the side of the tiny, angled tool. The inch or millimeter size may have rubbed off with use or may be entirely too small to read. In this case, an Allen wrench or hex key chart can make finding the right size for your socket head much easier.

What are Allen key screws called?

Socket Head Cap Screws, which are also known as Allen head screws are stock items at Lightning Bolt in many materials sizes. These screws come with a hexagonal cross-section socket in the head and require an Allen wrench or hex key to drive them into material and secure them into a structure.

Why do hex screws exist?

You get screws with many different heads. All are designed to allow someone a good stable grip before applying the force needed to drive the screw in or out. You normally find hex heads on bolts but you do find them on screws. A hex head screw just allows the use of a socket attachment on a drill to do this.

What's the difference between imperial and metric Allen keys?

Imperial Hex KeyMetric Hex Size5/64″2 mm3/32″2.5 mm7/64″3 mm1/8″3.5 mm

Can you put an Allen key in a drill?

Can I put an Allen wrench in a drill? Yes. You can cut off the branch of the L-shaped hex key. Create a straight wrench that can fit into the chuck of a power drill.

Why is it called Phillips head?

Henry Frank Phillips (June 4, 1889 – April 13, 1958) was an American businessman from Portland, Oregon. The Phillips-head (“crosshead”) screw and screwdriver are named after him. … Thompson who, in 1932, patented (#1,908,080) a recessed cruciform screw and in 1933, a screwdriver for it.

Why does furniture use Allen keys?

When assembling the furniture, owners use the hex keys to install fasteners and connect the various pieces together. The small and crammed spaces of furniture allow hex keys to easily fit inside and turn the fasteners.

What is Torx key?

Torx keys are also commonly known as star keys. Like hexagon allen keys, most torx keys are small enough to be carried in a pocket and enable the user to drive the appropriate fasteners without needing a separate screwdriver or power tool.

What is ratchet tool?

A ratchet is a common wrench device with a fastener component. A ratchet wrench is an essential tool that is used to fasten or loosen nuts and bolts.

What is the Allen wrench for on a guitar?

Put the Allen key away and step away from the guitar! Seriously, if you don’t know what it is for, leave it. It adjusts the truss rod, which adjusts tension in the neck to be bowed, back-bowed or flat. It is sensitive and over doing it can be very bad.

What does SAE stand for in tools?

SAE stands for Society of Automotive Engineers. This form of measurement was used primarily on cars made in the USA. This is why more often than not if you’re in the United States, you’re most likely finding wrenches and sockets in SAE sizings. AE sockets are sized in inches and fractions of inches.

How is a carpet knife different from a common utility knife?

The key differences between them is that a Carpet Knife is designed for a specialized purpose while the Utility Knife is an all around type of knife – which can be used virtually to any lightweight material. The Carpet Knife is specially made for Cutting through pieces of tough and lightweight fabrics.

Who invented the Allen key?

In 1909–1910, William G. Allen too patented a method of cold-forming screw heads around a hexagonal die (U.S. Patent 960,244).

What side of Allen wrench do you use?

When you need to use the Allen wrench, stick the short end of the L shape into the bolt head and press down on the longer side of the L to turn the bolt. Of course, the Allen wrench will only fit in a hex bolt (a bolt with six sides), so don’t try using the Allen wrench to screw in any other type of fastener.

What is the biggest allen key size?

Hex sizeLength long armLength short arm1/16 inch91 mm15 mm5/64 inch100 mm16 mm3/32 inch112 mm18 mm7/64 inch119 mm19 mm

What are Imperial keys?

ALLEN KEYS metric imperial AF sizes Allen wrench is a tool of hexagonal cross-section used to drive bolts and screws that have a hexagonal socket in the head (internal-wrenching hexagon drive).