ThePipingMart Blog Fasteners 3 Types of Allen Key Bolt and Their Uses

3 Types of Allen Key Bolt and Their Uses

Allen Key Bolt

Have you ever noticed the small hexagonal-shaped head on a bolt and wondered what it was? If so, then you’ve seen an Allen key bolt. These bolts are used in many applications and are favored for their ease of use and versatility. Let’s take a look at some of the different types of Allen key bolts out there and how they can be used.

Types of Allen Key Bolt

Socket Head Cap Scre

Socket head cap screws are probably the most common type of Allen key bolt out there. These bolts have a hexagonal head with an internal socket drive that is often referred to as an “Allen socket” or an “internal hex drive.” Socket head cap screws are available in both metric and imperial sizes, with the most common sizes ranging from M2 up to M12 (imperial sizes range from #0 to ¼ inch). The benefit of these screws is that they can be used in tight spaces where other types of screws would not fit.

Button Head Screw

Button head screws are similar to socket head cap screws but have a slightly different shape. Instead of the flat top that is present on socket head cap screws, button heads have a rounded top that gives them a low profile when installed. They also have a slightly larger diameter than socket head cap screws and are available in metric and imperial sizes, ranging from M3 to M20 (imperial sizes range from #2 up to ¼ inch). Button head screws are ideal for applications where aesthetics matter, as their low profile makes them less visible when installed.

Set Screw

Set screws or grub screws are another type of Allen key bolt that is commonly used in applications where added strength is required. Unlike other types of Allen key bolts, the set screw has no head; instead, it has a threaded shaft that is designed to be inserted into a tapped hole or threaded nut. Set screws come in various lengths, diameters, and thread pitches, making them highly versatile and customizable for any application.


Allen key bolts offer many advantages over traditional fasteners due to their ease of use and versatility. Whether you need something strong like a set screw or something low profile like button heads, there is an Allen key bolt for every job! Understanding the different types of these bolts will help you make informed decisions about which one best suits your needs for any given project.

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