pic: Arm joint idea

[AdamHeard]

Originally Posted by Hachiban VIII

Thats pretty cool. But I don't see why you didn't just use square tubing the whole way.

Yes, square tubes aren't as torsionally stiff, but I'd think the lack of a joint would make up for it.

I have bad memories of team 852's fiberglass tube arm getting snaped off at the base at CalGames '07.

The round tube will be a bit lighter, and more torsionally stiff (as you said) than a square tube of the same size.

The other reason I see teams go with round is that they are using PVC pipe. I know you're aware, but you can't just go and by that at Home Depot (or anywhere... I'm not sure, I've never tried to find PVC square tubing). The teams often like to use the PVC as it's so elastic and rather hard to break.

Also, about your last statement, i think we should separate the material vs. shape argument. Without knowing anything about their robot that year, I'd imagine that the failure wasn't from the shape of the tubing, but rather how they were holding onto it. You really need to clamp it, fastening to it is a bad idea.