What is a good covering for the bottom of the robot chassis to mount things like the control system, battery, compressor, pneumatic manifold, motor controllers, etc.? Last year was my team’s rookie year and be used a piece of pegboard (something like this). Probably needless to say, it didn’t really hold up too well under the weight of heavier items (mainly the battery) and started to fall apart from the stresses of competition. I was wondering what other teams liked to use and what their experiences with different materials were.
Baltic birch plywood, if you can find some, cuts well and looks nice–and it’s an insulating material. It’s also pretty light.
I know many teams use some forms of plastic, mostly polycarbonate.
I’ve also seen teams use aluminium plate with nylon bolts for attaching parts.
Plywood will work fine, as long as you make sure it is adequately supported around the battery area. We used 3/16" for the belly pan (as well as the rest of the chassis) and it holds up fine.
I have heard of teams using birch plywood, G-10 or garolite, and perforated polycarb. Just as a side note, we have used 1/16" perforated 3003 aluminum sheet for our bellypan and I would not recommend it. It sagged and bent around the edges like crazy. Maybe go thicker if you can find it, or 6061, but that is very expensive.
1/4 to 1/2" plywood usually works ok, although you need to provide some extra bracing under the battery unless it’s right at the edge of the robot. Pegboard is not very strong…plywood is stronger. If you want to get fancy, you can use plastic or metal, but you might find that plywood gives you more stiffness for the weight, and is easy to attach stuff to, and the insulating is a good thing as well. It’s not quite as “high tech” looking as other materials, for whatever that is worth.
You’d do best to avoid placing the battery directly on the bellypan/electrical board without other framework. The best thing to do would be to integrate some sort of specific case for the battery with the rest of the framework on the robot.
For the past 2 years at least, Team 20 has used Garolite for the past two years to cover the bottom of our chassis, as well as to mount the majority of our electronics. I cannot remember the thickness we used, probably 1/8". So far, it has worked well for us, since it’s lightweight and relatively strong.
1/4" plywood is what I recommend. To stiffen it up a piece or two of 1x1 angle placed on the top works well to support the battery. If you space it just slightly larger than the battery so the edges of the battery rest on it then you’ve got the battery constrained in one axis. Use a small piece of the 1x1 angle to make a bracket to attach it to the frame on each end.
Can you machine on garolite easily? I’ve been thinking about using it, but hear bad things like delaminatione can happen.
I’m not too sure about the machinability, but as far as I know, we haven’t had any major issues as of yet.
We used 1/8" polycarbonate sheet last year and it worked great. More commonly available at Home Depot, Lowes, and Menards than birch plywood, which can be somewhat of a specialty item. Polycarbonate sourced there is cheaper than the sheets that AndyMark stocks.
I would avoid using construction grade SPF plywood in a 3/8" thickness, as its quality varies widely and won’t hold up as well as birch, which has more glue in it.
You’ll find that acrylic sheet is also available and cheaper, but you shouldn’t use it. It breaks too easily, and the broken pieces are quite sharp.
We’re experimenting with a custom carbon fiber composite belly pan. We’re taking a thick foam core and CNC’ing grooves for strength, for a battery holder, and for mounting electrical components. Then we layer this in sheets of glass fiber and carbon fiber, epoxy it, and vacuum out the excess air while it cures. This takes more time and more planning, but has given us a much better result than the 1/16th aluminum that we used last year.
Plywood, polycarbonate, and sheet aluminum are all going to work well for this. Plywood and polycarbonate are a bit better than the aluminum in my opinion. The reason for this is it makes sure any electronics you mount to it are electrically isolated from the frame. Though, this is almost as easily done with double sided tape or Velcro. The take away from this is, use what ever material meets your budgetary and aesthetic needs.
One thing to note, If you want to use this as an element to stiffen up your chassis, use more screws than you would think. More smaller screws are better in this regard. One 10-24 screw every 4 inches or so around the perimeter works pretty well. Much better than just securing the corners.
The 2015- control system does not have any components with grounded cases that require isolated mountings.
My team used to mount the battery to a section of the frame and use smaller pieces of aluminum angle to make sure it couldn’t move/slide. A velcro wrap was then used to secure it in the battery holder (think like a cup holder).
For most of the electronics, we would use corrugated plastic (often used for yard signs) because it was light and cheap as well as sturdy enough. Usually we had sections for different parts of the electrical system and the sections could be removed to get to specific areas of the robot. They were all held on with velcro
Even so, the frame isolation requirement (R37) is likely to return for 2015 – it has been part of every FRC Manual that I can recall. Many instances of isolation failure that I have seen, while inspecting FRC robots, have been caused by poor wiring – and were therefore intermittent.
Also, a non-conductive wiring substrate will not produce conductive chips when you drill it at the last minute to re-position control system components.
Doesn’t the axis camera have a grounded enclosure?
The 206 does, but Axis doesn’t make them anymore. The M1011 and M1013 screws and enclosures are isolated.
Good catch. I’ve never had much time to play with the new ones yet, and just figured they were the same.