Fastener tech

[lak2004]

Ok so I was just looking through the Bolt Depot website and wondering what the difference between coarse and fine threads is (besides the obvious).

Are there times when one should be used over the other or just user preference?

So school me. Also when is Grade 8 necessary over Grade 5. Thanks

 

[thorguy57]

Grade 8 has a higher tensile strength then grade 5 does. So if you have high torque applications you would use a grade 8. From what I understand a fine thread bolt will give you a better clamping force because of the more threads per inch. It distributes the load over more threads. Coarse threads are harder to cross thread and also are more durable. I would almost always use a coarse thread unless I had a specific application that need a fine thread, like something subject to a lot of vibration might have fine thread.

 

[Scuba Steve]

This might help.
http://www.pirate4x4.com/tech/billavista/NutsandBolts/index.html

 

[rdn2blazer]

Also, a fine thread fastener it tecnically stronger. The minor diameter is larger then a course thread fastener. In the aerospace industry which I'm in we use exclusively fine thread fasteners for flight.

 

[cybrfire]

Another advantage of fine threads, they resist vibration loosening better than coarse thread do. Goes back to the higher TPI.