[robz71lm7]

So a certain student's machine design professor has pushed the idea into people's heads that we should use SAE Grade 5.2 or greater for all thing structural or important. Good luck finding those bolts, I knew they existed, but have never seen any. His logic is that the yield strength of a grade 5 bolt changes when you get over a certain diameter (1" IIRC) whereas the 5.2 grade's yield strength is constant. We also had a machine design project where we had to specify a size and preload for a grade 7 bolt. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/rolleyes.gif) Also according to him, nobody makes bolts with cut threads any more. Aren't most cheap chinese bolts manufactured with cut threads?

[nape]

Yuck.

I'm a guy who never made it past the "weed out" classes, but do you guys have to do budgeting or anything for your design projects? If so, make sure you check out the next grade up that is readily available to see the price difference. I say this because I've seen some amazing things in reference to purchasing vs. engineering. Purchasing doesn't know the difference between Grade 5, 5.2, or Grade 12345. They order what they're told, even if something equivalent would get the job done for 1/10th the money.

If not, remember it for when you're designing things and the one ordering them isn't an engineer (IMG:http://www.frrax.com/rrforum/style_emoticons/default/laugh.gif)

Good luck with the class, sounds like a pain.