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Resilient
03-08-2009, 04:13 PM
I am starting work on a robot for a firefighting competition. I see that many of these size rovers use some sort of plastic sheets to mount all the components to.

What thickness is sufficient to eliminate excessive flexing on a robot that's roughly a 12"x12" square?

Also, what material is recommended? I am looking at TAP plastic (http://www.tapplastics.com/shop/category.php?bid=24&) and there seem to be quite a few possibilities for plastic sheets. Polycarbonate is on the expensive end and PVC and HDPE are on the less expensive end.

lnxfergy
03-08-2009, 06:05 PM
I am starting work on a robot for a firefighting competition. I see that many of these size rovers use some sort of plastic sheets to mount all the components to.

What thickness is sufficient to eliminate excessive flexing on a robot that's roughly a 12"x12" square?

Also, what material is recommended? I am looking at TAP plastic (http://www.tapplastics.com/shop/category.php?bid=24&) and there seem to be quite a few possibilities for plastic sheets. Polycarbonate is on the expensive end and PVC and HDPE are on the less expensive end.

I use EPVC (expanded PVC) on my smaller bots.

By firefighting, I assume you are building something for either the Trinity Fire Fighting Contest, or one of it's derivatives. In that case, a word of caution -- don't make your bot 12"x12". Sure the rules say thats the maximum size, but in reality, most of the competitive bots are WAY SMALLER. LGM3 (http://blunderingbotics.com/xrb4.php), the 2008 CNRG champion is only 8"x8". My newer bot is about 6.5"x6.5". A smaller bot will have a much easier time navigating the maze.

-Fergs

Resilient
03-08-2009, 06:11 PM
Yeah, I am expecting to have something in the 8x8 range. But as far as flex is concerned, I figured I would error on the side of needing something that would be strong enough for a 12x12.

What thickness EPVC are you using? I looked at your Xrb7 images and it looks fairly thick.

lnxfergy
03-08-2009, 06:42 PM
1/4" (6mm). Its really lightweight and easy to work with. You can cut it with just about any kind of saw, and sandpaper can clean edges up. I like to use a bandsaw for rough cutting it, a scrollsaw to take internal cuts and details, and then clean up the edges with a beltsander and/or files

You can get a 12"x12" sheet for about $6 from these guys http://www.budgetrobotics.com/shop/?cart=744490&cat=103& but their choice of colors has gone way down.

Alternatively, you can use that 0.220 lexan from HD or lowes. Avoid the acrylic sheets though, as they can generate gobs of static.

-Fergs