pic: Team 1714's 2011 Robot

[eric1010]

Yes, a single motor drives the arm. The cylinder is a counterbalance.
The weight is very close to 120 lbs

[Navid Shafa]

Originally Posted by eric1010

The weight is very close to 120 lbs

That is so hard to believe! I am surprised that it weighs that much...

Rough stats gives the weight of unfilled polycarbonate at 0.043 pounds per cubic inch and the weight of comparative aluminum 6061 at .098 pounds per cubic inch.

I'm sure you pushed the envelope, just would really love to hear where most of that weight went

Nice work, Like the design!

[Dr Theta]

It looks great, and I can only assume that with "continuous improvement" it will be even more beastly when I get to see it in person. I was really excited to see that you guys decided to return to Minnesota. Great team, great robots, enough said.

[Snalios]

Originally Posted by Navid Shafa

That is so hard to believe! I am surprised that it weighs that much...

Rough stats gives the weight of unfilled polycarbonate at 0.043 pounds per cubic inch and the weight of comparative aluminum 6061 at .098 pounds per cubic inch.

I'm sure you pushed the envelope, just would really love to hear where most of that weight went

Nice work, Like the design!

Its not that hard to believe, considering that lexan weights more then aluminum.

[Nuttyman54]

Originally Posted by Snalios

Its not that hard to believe, considering that lexan weights more then aluminum.

Polycarbonate (Lexan) weighs about half as much as the same size piece of aluminum. However, it is not nearly as stiff. To achieve a similar stiffness (which is necessary in things like arms, chassis, etc.) you're going to end up at around the same weight as if you did it with aluminum, maybe even a little heavier. The weight in this robot probably went towards making it stiff enough for the rigors of competition (drivetrains that flex are not fun).

[Chris is me]

Originally Posted by Snalios

Its not that hard to believe, considering that lexan weights more then aluminum.

This isn't true.

[Navid Shafa]

Originally Posted by Snalios

Its not that hard to believe, considering that lexan weights more then aluminum.

Did you not see the stats I posted? I am not saying that I have the exact wieghts per cubic inch, but I'm pretty sure that they're close...

Also, Thanks Nuttyman54 and AdamHeard. Sure it could weigh the same as aluminum if it has increased the thickness, but from the picture, I had trouble noticing any difference in thickness considering it's practically invisible

[AdamHeard]

Originally Posted by Navid Shafa

That is so hard to believe! I am surprised that it weighs that much...

Rough stats gives the weight of unfilled polycarbonate at 0.043 pounds per cubic inch and the weight of comparative aluminum 6061 at .098 pounds per cubic inch.

I'm sure you pushed the envelope, just would really love to hear where most of that weight went

Nice work, Like the design!

it's less dense than aluminum, but it's used in thicker (and larger pieces) usually. Most of the structural tubing on our robots is 1/16" wall thickness, occasionally 1/8". 1/2" polycarbonate is substantially heavier, while still being less dense.