Coarse thread fasteners versus fine thread fasteners is one of the most common questions in the industry. Surprisingly, many people don't know that there are some significant tradeoffs to the type of threading chosen for a project. Each type of thread has some advantages that the other lacks.
Threads are uniform projections of varying height and width (from one fastener to another) that surround a cylinder. This helical shape wire can be wide or deep, which is considered a thick wire, while a narrower helical shape with shallow grooves is considered a thin wire. Both have advantages that the other lacks, so which one should you choose?
Thick yarn
Coarse thread fasteners are an excellent choice for most applications. Often chosen for construction simply because their threads can be slightly damaged and still function effectively. The coarse thread allows more material to fit between these threads during installation. Because of this, it is more difficult for thick thread fasteners to strip or cross the thread. Its extra tolerance allows for nicks or damage to form on the thread edges without inhibiting the ability to clamp them.
Thick threads are also much less likely to fray than thin threads. Fine threading requires many more turns per inch, which creates more friction. Excess friction greatly increases the chance of fastener wear. In any case, it is recommended to use an anti-seize solution, especially on stainless steel fasteners. Thick line also handles obstructions (like dirt) in the line better. They can be repaired even when they are not completely clean.
Thin yarn
While coarse thread fasteners are best suited for general purpose applications, fine thread applications tend to have many advantages that make them an ideal choice when specifications are important. Thin thread has higher tensile strength than thick thread and can be measured more accurately. Which makes them the ideal choice for specific resistance applications.
Fine threading consists of very shallow peaks and valleys compared to coarse threading. As a result, drilling a hole for fine threading can be significantly easier as there is much less material to cut to form the threads. The fine thread also has a very low pitch (helical angle). This makes vibrations less effective in loosening fasteners over time. Fine thread fasteners are ideal for environments where vibration is considered a problem.
Now that you know how to compare coarse-thread and fine-thread fasteners, you can make the right choice when deciding which fasteners you need for a project. For more information about fasteners, check out our Fasteners 101 reference pages.
