Which kind of Aluminum is a good choice

[nuclearnerd]

Originally Posted by Cory

This is terrible advice and I hope people don't blindly take it. You cannot possibly make a blanket statement like that without way more justification.

You're free to disagree, but I provided context and a justification.

Originally Posted by Cory

So yes...if you want to be absolutely sure that you can mask most possible bad design decisions with material choice, feel free to use steel...

There's a fine justification right there. This is a student competition after all. Even the pros get it wrong sometimes (I won't single out a supplier here), so it's nice to have some margin.

Originally Posted by Cory

just don't wonder why your robot doesn't make weight.

The difference honestly isn't worth it for small parts. You'd be looking at a difference less than 1/2 a pound between steel and aluminum for the size of parts I'm talking about, and less if you design the steel piece to take advantage of the improved properties.

If you can buy a COTS part in hard-anodized 7075-t6 and it comes with a good reputation, by all means - enjoy the tiny weight savings (and reduced wear life). But if you are designing a small, highly stressed component in house, I suggest you save yourself the hassle.