[EricH]

Originally Posted by asid61

I thought screws were meant to be in shear load? 10-32 screws have ratings in the hundreds of pounds range IIRC.

It depends on the screw and arrangement. Generally, an individual screw is meant to handle tension loads. However, in the right arrangement, they can handle pretty high-shear loads.

I broke out my machine-design textbook--it's really handy for a lot of things with robotics, including a general screw-bolt-nut overview. (Also one of the few chapters I didn't get into in college.) The answer there is that generally, screws are for tensile loads, but in structure use, they're often used to resist shear. BUT, those shear loads are taken when the screw is already in tension. The suggestion from the book is to use dowel pins in machine-type shear situations to assist the screws.

I've seen what sometimes happens when a lone screw takes a shear load. It's not fun to hear if it's a good-sized screw. Come to think of it, I don't know if we ever did find that one screw/bolt head...