Tag Archives: Difference between thread classes

Fastener Thread Class – 2A and 3A Threads, What’s the Difference?

Posted on July 7, 2021 by Kathleen

Q: My customer called out a 3a thread for their hex head screws. Is this different from a 2a thread pitch? A: Yes these are 3 different classes of fit for external inch series threads for studs, bolts, and screws 1A, 2A and 3A. 2A thread class is a medium fit, whereas … Continue reading →

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