What Is A Good Safety Factor For Threaded Rod

[bostonman]

I have two more threaded rod questions.

How does the tensile strength change when the rod is bent? If say the rod was mounted vertically on a bracket that was 6" away from a wall and the object it supports is 8" away, this would cause the rod to bend. I'm not looking for an exact answer, but curious how the force(s) on the rod changes. I'm sure a longer rod would be more forgiving whereas a short one would probably snap.

My other question is just basically what happens to a long length of threaded rod if someone tries to bend it; just one bend, not back and forth which would certainly cause it to break? Does it eventually kink, snap, or take the bent shape? It obviously depends on the arc, so guess maybe I'm referring to a length of several feet where one end is in a vice and the other end getting the force so maybe the object is to have both ends touching.

My experience with bolts and screws is they just bend, but usually they are too short for attempting to bend them to such a degree.

The rod I had was 96" (3/8" x 24) and too expensive to experiment with.

[jpanhalt]

If you bend a threaded rod, you will mostly see difficulty moving a nut over the bend area.  Threaded fasteners are very sensitive to distortion of the threads in either part.

Mild steel is pretty forgiving to being bent over a sufficient radius.  That radius varies with thickness.  Tables are available for most common metals, like mild steel, most stainless alloys (like 303), and most aluminum alloys.

[bostonman]

If you bend a threaded rod, you will mostly see difficulty moving a nut over the bend area.  Threaded connectors are very sensitive to distortion of the threads in either part.

I wasn't referring to whether a nut can be threaded, it was more of a general question of strength degrading on the rod.

[jpanhalt]

Obviously a threaded rod has "creases" in it, and that weakens it.  Bending will probably weaken it more.  Will that affect your use?  I doubt it.  Just FYI, critical threaded rods in aircraft are often/usually specified to be "rolled thread."  They are quite strong, but I can't imagine you need to go to that bother.