Hex Cap Screws vs Hex Tap Bolts: What’s The Difference?

Hex bolts, hex caps, hex taps, hex heads…there is so much hex bolt lingo.

Hex bolts can be very confusing. Its one of those situations where you may order a hex cap screw and wind up with a hex tap bolt. A hex cap is sometimes a hex tap, and Albany County Fasteners would like to take some time today to explain the details of hex bolts to you. It’s all about the threading, the length and the shoulder.

Hex Bolts

Hex Bolts are bolts with external threading and a hex head designed to be driven by a wrench. Hex bolts may be partially threaded or fully threaded, and are available in hex cap (partially threaded after a certain length) and hex tap (always fully threaded). Hex caps and hex taps are both considered “hex bolts”. Hex bolts are designed to be inserted into holes with machined, tapped threads, they are available in coarse thread (UNC) and fine thread (UNF).  Machine screw sizes (diameters #4 – #12) of hex bolts are known as “trim head hex screws” and are always fully threaded.

Hex Cap Screws / Hex Cap Bolts

Hex cap screws may have a built-in shoulder (un-threaded area under the head) which increases tensile strength of the bolt. However, the threaded length of these screws may be limited and therefore, they are not suitable for all applications. Cap screws are typically fully threaded up to 1-1/4″, hex cap bolts over this length are almost always partially threaded. Hex cap screws are available in diameters 1/4″ and up. Browse our selection of hex cap screws.

 

Hex Tap Bolts

Tap Bolts on the other hand are fully threaded regardless of size. This means the threading goes from the tip all the way to the underside of the head of the bolt. They have a weaker tensile strength but the extended threads make them more suitable for situations where hex cap screws may not function well. Hex tap bolts are available in diameters 1/4″ and up. Browse our selection of hex tap bolts.

In Summary

Tap bolts have threading all the way down regardless of their size. Hex cap screws may have a shoulder in longer sizes, which makes them stronger. Both are typically installed with a nut and designed to be driven by a wrench or socket driver. And last but not least, if a hex cap screw is small enough to lose its shoulder it can also be considered a tap bolt. In smaller sizes, they are the same but once a unthreaded shoulder starts, become different bolts. Browse our entire selection of hex bolts.