Has any team or anybody made a 80% - 100% lexan bot?

[JVN]

Originally Posted by Max Lobovsky

I was already on it...

Cool!
Thanks a lot. It is always nice to see someone back up their argument with numbers. Props to you, AND to Arefin for taking the time to do some research (Which is very important when doing design and analysis.)

You guys rock,
John

[Alaina]

Funny, there haven't really been any references to plywood in this thread.
For my team's first 2 years we used 3/8" plywood. Though in 2002 we had this large steel "knee breaker" apparatus that was used to grab ahold of goals. In 2003, however, the only metal you could see on the robot was the angled alluminum, 1/4-20 bolts and lock nuts used to hold the chassis together. It was sweet.

[ahecht]

Originally Posted by Max Lobovsky

GE Lexan (clear, no glass) ---72 MPa -----1.2 g/cm3----- ratio 60
Aluminum 6061-T6 ---------310 MPa -----2.7 g/cm3 ---ratio 114

Yes, but other aluminums don't fare as well. 5052 aluminum, for example, has ratios between 70 and 100. Other aluminums range from a ratio of 17 to a ratio of 237.

[MrToast]

Originally Posted by Thread Title

Has any team or anybody made a ...100% lexan bot?

Yes, but the lexan motors kept on melting....

MrToast

[Max Lobovsky]

Originally Posted by ahecht

Yes, but other aluminums don't fare as well. 5052 aluminum, for example, has ratios between 70 and 100. Other aluminums range from a ratio of 17 to a ratio of 237.

6061 is definitley the most commonly available (and probably one of the cheapest) types of aluminum used structurally. Most of the aluminum extrusion kits, and most of the tubing/angle/channel found on FIRST robots is 6061.

Additionally, Polycarbonate varies (you'd have to go to some other brand than Lexan) and glass filled PCs have ratios around about 80. I'm pretty sure glass filled PC is too hard and brittle for most framing use.

[Max Lobovsky]

And just because the use of this by teams that have plenty of metal machining capabilities annoys me:

pipe type PVC ------ ratio 31

[Dick Linn]

Team 346 (Richmond) made one in 2001, I believe it was. There were a couple of pieces of aluminum angle connecting the Hyzod platform to the side panels. Each side was doubled up and contained a chain driving 3 wheels. It looked very much like one of those WWI tanks, as the front was intended to crawl over the 4x4 in the middle of the playing field. The polycarb was appx. 3/8" if I recall. I don't have pictures, but perhaps someone from 346 does. The frame held up well, although the bot was pretty light.

[Tom Bottiglieri]

Originally Posted by Max Lobovsky

And just because the use of this by teams that have plenty of metal machining capabilities annoys me:

pipe type PVC ------ ratio 31

what exactly annoys you?

[JamesCH95]

Originally Posted by Arefin Bari

One reason i am against using lexan as the chassis... it may break. example was given by greg...

I agree. Plus Lexan is expensive. I'm on 95, and we hardly spend any money on our 'bots. We use 9-layer baltic plywood becuase i can absorb damage much more easily. Plus it's really easy to mount things to. But Lexan does look pretty cool.

[Gdeaver]

Since this thread has turned to a choice of materials discussion, I would like to point out that in the past 3 years I have noticed a increase in rough play in the game. In 2004 we took several high impact hits. We fortunately survived them with no damage. I would suggest that all teams look at the materials and design with the goal of surviving high speed point impacts. More and more teams are using multiple motor trans and the power and speed is increasing. Plan for it or you'll find you self in the pits making emergency repairs. What worked in the past may not work as well for 2005.
First has opened up the allowed materials. Evaluate the choices and use them.