What is an Allen Wrench?

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. And as you may have guessed, it’s the tool displayed in the picture above. The name Allen comes from it’s origins as a registered trademark of the former Allen Manufacturing Company from Hartford, CT. As of right now, it’s currently owned by Apex Tool Group (ATG). It’s our understanding that ATG would prefer that the standard name, “hex key“, pick up momentum (which is certainly understandable). However, it appears that Americans have decided that they prefer the name, “Allen wrench”.

Different Types of Hex Keys

Flat End vs. Ball End

Most hex keys and bits feature the traditional flat ends as they are suitable for most uses. The flat end allows for the key to fit closely inside the screw head or nut. Thus, you should always use one of these when applying a lot of force to the wrench. On the other hand, ball-end hex keys are designed for when the user needs to fasten a nut at an angle. Most ball-end hex keys work within 25 degrees of the point of entry, which makes them ideal for tight spaces. You can certainly use a ball-end hex key for everyday use. However, they are more prone to breaking and are generally a bit more expensive to replace.

Short Arm vs. Long Arm

This one is pretty self-explanatory at this point in the article. On most hex keys, the vertical length is always longer than the horizontal length. And the long-arm and short-arm modifiers tell us the extent for that difference in length. For long arm hex keys, they are typically at least twice as long in the vertical direction than they are in the horizontal direction. Conversely, short arm hex keys are generally about 50% longer on the vertical side than on the horizontal side.

Hex Key Uses & Applications

Now that we’ve covered what an Allen wrench is, let’s go over its uses. Hex keys are a staple for every mechanic, electrician, & machinist. The compact size of a hex screw makes it a great candidate for any application with size constraints. Thus, everything from cars to handheld electronics rely on Allen wrenches for basic repairs. A number of machines and power tools also require hex keys for adjusting their settings and positioning. For instance, our own counter sink drill bits rely on hex screws to adjust the depth. This allows for the screw to still fit into tight spaces.