Should I Use Coarse- or Fine-Thread Bolts?

Different projects require different kinds of bolts.

Use Coarse-Thread Bolts for Heavy-Duty Projects

Coarse-thread bolts are durable, and resistant to stripping, an important consideration when choosing bolts for a heavy-duty project. They also install more quickly and, due to their coarseness, are less likely to become nicked or damaged.

Use Fine-Thread Bolts for Special Projects

Fine-thread bolts, interestingly, are "stronger than the corresponding coarse threaded bolts of the same hardness," according to fastening experts at Kato Fastening Systems Inc., a supplier of the North American fastener market. They are also more resistant to loosening when they encounter vibration, due to the angle of the threads, and can be more precisely adjusted.

Bottom Line

KATO Fastening Systems recommends using coarse-thread bolts "for most industrial applications unless there is a convincing reason not to do so." Use fine-thread bolts when the project requires "finer adjustments" or when you need to more easily "tap into difficult to tap materials, and thin walled sections."

References

• Kato: Coarse Threads Vs. Fine Threads
• Accurate Screw: Thread Series Tech Tips
• Tapmatic: Coarse vs. Fine Threads