Hex keys are tools with a thin rod having a hexagonal tip. They are used for tightening and loosening bolts, and have a large number of applications in DIY as well as industries. In this article, we will introduce the specific types of hex keys and how to use them.

What is a Hexagonal Bar Wrench?

Hexagonal wrenches are tools used to fasten and unscrew hexagon socket head bolts. It is called variously: Hexagonal Bar Wrench, Hexagonal Bar Wrench, Hexagonal Wrench, Hex, and so on. These tools are used on bicycles, furniture, and mechanical equipment, and are sometimes attached to furniture that needs to be assembled.

Hexagonal wrenches have a large contact area when inserted into a bolt hole, a property that makes it difficult to break a bolt. For example, some people may have experienced breaking screw holes when using a Phillips or flathead screwdriver for screws. However, in the case of hexagonal wrenches, since they are used in exactly the right size, damage to the bolt can be prevented as when using a screwdriver.

What is a hex key?

Hex keys are tools used to fasten and unscrew hexagon socket head bolts. There are various names for this tool such as allen key, allen wrench, hex wrench, hexagonal bar wrench, hexagonal wrench, hex, and so on. These tools are used on bicycles, furniture, and mechanical equipment, and are sometimes attached to furniture that needs to be assembled.

Hex keys have a large contact area when inserted into a bolt hole, a feature that makes it difficult to break a bolt. For example, some people may have experienced breaking screw holes when using a Phillips or flathead screwdriver for screws. However, in the case of hex keys, since they are used in exactly the right size, damage to the bolt can be prevented.

Types of hex keys

The two most frequently used types of hex keys are 3mm and 6mm, but the smaller sizes can easily be lost, so there are ways to choose products sold as a set. There are different types of hex keys, such as screwdriver type, L-type, T-type, folding type, and hexagon socket.

Screwdriver type

The screwdriver type is characterized by its screwdriver shape and easy-to-grip construction. Since it can be turned while pushing like a screwdriver, it is easy to operate and convenient.

L-shape type

The L-shaped type has an L-shaped handle, and the short end of the handle can be used for fast turning, while the long end can be used for tightening. This type is suitable for those who use different sizes of hex keys for various operations.

T-shape type

The T-shape type has a T-shaped handle that makes it easy to apply force and turn quickly. This type of wrench is recommended for those who want to focus on working speed.

Folding type

The folding type is compact and portable, with multiple sizes in one. There is no need to worry about losing them, and they are compact and can be folded for storage.

Hexagon socket type

The hexagon socket type is used in combination with a ratchet handle. Combined with attachments and handles, it is easy to work in tight or complicated places.

 

Types of hexagonal wrench tip shapes

Hexagonal wrench tips are available in standard hexagonal, pole point, and torx shapes. hex keys have a hexagonal hole on the bolt, while pole point wrenches have a rounded tip and can be accessed from an angle of 0 to 25 degrees.

How to use a hex key

The basic rule of using a hex key is to use a tool that fits the size of the bolt. When the short end is inserted, it can be tightened or loosened with high force, and both can be used in different ways depending on the intended use.

For a pole point with a round tip, insert the hex key at an angle to the bolt. In this case, the tip may be damaged by strong torque due to the small contact surface. It is thus best to avoid using for final tightening or loosening.

In terms of caution with hex keys, strong force can break not only the bolt but also the wrench; moving the L-shaped wrench in such a way that it tilts upward or downward or turning it while the shaft is tipped over can damage the hexagonal tip. It is dangerous to break a wrench, so do not apply torque beyond the wrench's capacity (refer to the JIS standard).

As a rule of thumb when tightening a screw or bolt with a hex key, it is enough until the wrench deflects about 20mm. When tightening a screw or bolt, applying a stronger torque will not be effective. If you feel that the screw or bolt will not go in, clean the hole.

If a bolt becomes rusted and will not come off, excessive torque will be required and may result in damage. In such cases, a pre-applied penetrating lubricant can reduce friction. Spray the entire joint surface of the nut and bolt, and allow at least 10 minutes before beginning the loosening process. When re-tightening, wipe off the penetrating lubricant thoroughly, then insert a hexagonal wrench and retighten the bolt. If any component of the lubricant remains, the torque will be reduced and the bolt will easily break due to over-tightening.

Hex keys are often sold in sets of several sizes, and some products are compact and can be stored easily, so it is convenient to have one ready. Pole points have the advantage of allowing tools to be inserted at an angle, so it is better to prepare enough space to turn them. 

Hex keys are versatile tools with a large number of applications, at home and at work, across sectors, so it’s useful to understand how they work.