Quote Originally Posted by curious aardvark View Post
Modern pla is NOT brittle - sheesh, where do people keep getting this crap from ?
It is stiffer than abs, but it's not brittle. If you hit it with a hammer it dents, it does not shatter.
It would be more accurate to say it is more brittle than ABS. That doesn't necessarily mean it will crumble when dropped. PLA biggest downfall (in my opinion) is its very lower glass point. It'll reach creep temperature on your average hot day here in Africa. Two other things that I personally don't like is that it doesn't sand as easily i.e. requires more elbow grease and that it can't be cold-welded. That, however, certainly doesn't make it a lesser material.

For the sake of the OP project I believe this needs to be approached completely differently. No load studies have been done so every suggestion so far is a shot in the dark, Perhaps the OP should find out the conditions of operation first. For example, if the robot is operating at a temp higher than 50C then PLA wouldn't be suitable. Then I would go ABS. If it operates in high humidity then nylon isn't recommended due to its moisture absorbtion rate (9%). If the robot is more of a project then PLA should fine. But first define the conditions.