Bottom Pan for Robot?

We are discussing putting a bottom pan on our robot and need to make a decision tonight. The discussion revolves around wood vs. thick plexi vs. old fashioned steel. We’ve got all the materials but wanted to see if this was overkill. I’m a bit old school in that I want to protect the bottom of the robot while going over the defenses and not get caught on them. We’re using Rhino drive and are staying low so we can “low bar” easily. I’m also old school in that I recommend steel since we’re way underweight. Thoughts? Any pearls would be welcome.


We added a thin sheet metal belly pan below our perforated aluminum sheet and no issues now. We had zip ties which secures our control system parts rip off prior to that since they stuck out under the bottom of the perforated sheet.

We have polycarbonate but steel could work.

Some questions though,
Is this structural or purely protective?
How thick/flexible is the plexi, wood, or steel?

We used a simple metal grate. Pretty light weight and strong.

We made our belly pan from a 1/4" sheet of 5051 aluminum. We figured we would need it after crossing a couple of defenses at high speeds.

Just as a thought… An awful lot of Defenses are, or have, steel in them. (Rock Wall and Rough Terrain come to mind immediately.) Steel on steel tends to produce sparks. Sparks tend to be bad, though they may look spectacular.

I’d use some thick sheet aluminum, maybe going up to thin plate aluminum. Wood is going to get shredded.

From Week 0 events, I would want protection from driving over a ball.

Non-conductive is good. That minimizes the risk of accidentally grounding the frame to the battery.

What is the ground clearance between the lowest point on the robot and the ground?

Ours was ~3" until we realized we had to protect the WCP transmissions since they stick down ~0.75" below our frame rail. We added ‘skid rails’ made of thick-wall 1x1 aluminum tubing. This removed the need for a separate belly pan/protective layer.

We have some more profiling to do with them to help with the ramparts, but otherwise the skid bars help us with the moat and rockwall with simple 45-degree chamfers on either end.

For our robots bottom pan we just have 1/8 inch plexiglass and it works just fine. I don’t think you think plexiglass for the bottom of the robot.

Our lower cover is made of 0.10" thick polycarbonate. It is flexible, so we were able to make it curve up at the front end. And it only took about 15 minutes to make it and install it…

I believe we have a 1/4" sheet of lexan that we also mount our electronics to. We don’t have any issues with zip ties or nuts since we tapped all the wholes so we can just cut the bolts to the needed length.

We’re using a 1/8" sheet of lexan that completely covers the underside of our robot, front to back. We’re avoiding mounting anything to it due to it needing to be quickly removable for easy access to components located lower in the robot.

We use 1/16" polycarbonate.

We used 1/4" poly as our belly pan, we are also using rhino drive.

We use expanded aluminum for the best of both worlds. We do not need to drill holes for the electrical belly pan, it is lightweight, won’t shatter, and it is stiff enough to bolt to the bottom of our robots easily with 1/4"-20 fasteners and washers. You could also weld it I suppose.

Here is the page where we get it:

We usually get the diamond shaped sheets. Cuts easily with sheet metal shears too.

Thanks! We ran with your idea with some thin steel. Got to teach the team how to use a manual brake (like for siding) as well. We don’t have any major power tools other than a drill press, small bandsaw and a bench grinder of 1950s vintage. Rest is hand tools only. Again…thanks for the info! Hopefully we’ll see you at the Dallas Regional