Cut vs. Rolled Threads
- Rolled threads, extruded by dies, are stronger than cut threads, made on a lathe or with a hand die, because their grain flows in more than one direction, following the contour of the fastener.
- So you shouldn’t re-cut the threads of a roll-threaded fastener. (Re-cutting may also affect heat treatment and plating. And when you re-cut, you lose about two threads because there’s not enough material on the taper between the threads and the shank.)
- Also, rolled threads are smoother than cut threads, so there are no high spots to prevent proper torquing or allow loosening.
- It takes a lot more labor to cut threads than to roll them, so it’s more costly.