A while back I came to the conclusion that the existing arenas that were getting used for insect class events were getting to the point where they weren’t going to be able to handle the 3lb bots that were showing up at events. That meant it was time for upgrades or a new arena, and I was sick of messing around with 80/20.
So, time for a new arena.
I’ll jump right to the good bit, I’m not just going to show you the build, I’m also making the files available for anyone that wants to examine, iterate, and evolve on the design. As I went through the build I made adjustments to the CAD to reflect tweaks I made to the real parts during the build to account for the realities of fabrication tolerances, tolerance stack-up, and general ease of use.
Some critical things to know about this build:
The design requirements had a few oddly specific elements that dictated some design decisions, including-
- The arena must fit on the existing trailer in whatever form it travels in and can take up no more than half the available width
- The arena must be able to roll through a standard door when packed for travel
- The arena must have an option for a pit/push-out
- The arena must be able to be set up from its packed configuration in under 30 minutes by 4 or more people – Note, the setscrews for the roof side were snug enough that half of them were pulled and replaced by bolts. This allows the other two (on opposing corners) to work for alignment and quick support during setup while making it easier to install/remove the roof, though a large mallet is still quite helpful
Beyond those requirements there were several other design goals that I included based on the prior arenas I’ve worked on, those were-
- Replacement of the polycarbonate should be simple and fast
- The polycarbonate should be fully floating in its frame
- The walls should support double layers with air gaps for dual 3/8″ polycarbonate should it be needed in the future
- Each element of the arena should be easy to maintain with minimal other elements needing disassembly to perform the maintenance
- Visibility and footprint should be as large as is practical
- The hazard area should have options for pits and a flat floor
- Setup should use as few tools as possible
- Use tube laser cutting for tube parts for easy replacement and fit-up
- The arena door and wall should be the same thing for maximum visibility – Note, the large size of these does mean there’s a bit of flex but there’s not much to be done there without adding a lot of weight or blocking sight lines
With all that, on to the build photos
First up, prepping the uprights and the leg mounts.
Next up, the floor and roof frames.
At this point things were getting bulky and hard to work around, so it was time for the transport cart.
On to the doors.
Now for a big batch of printed TPU polycarbonate supports, paint, and making sure stuff fits on the cart. You can also see the polycarbonate retainers that also join the internal and external door uprights. You can remove two from either side to have open access to the polycarbonate for replacement or cleaning.
The keen eyed may notice that the gussets on the cart change a bit between pictures, when designing the cart I kept clearance for the legs. When building the cart I decided to make the gussets larger, forgetting why I had made them a specific size. I then solved the clearance issue with an angle grinder and some more welding.
Also worth noting that the bushings that are eventually installed in half of the uprights (the hinge side, you’ll want one side to be the hinge and the other to be the long pin that’s shown later for locking it closed) are shaved down to fit snugly since they’re a line to line fit in the CAD. This allows you to effectively get a perfectly fit hinge without needing perfect tolerances.
Time for the floor, roof, and lighting.
Now for the finishing touches, long handled pins to lock the doors with easy to identify pull points and an assembled arena ready for combat.
Following the first event and the lessons you learn by doing there are a few adjustments/upgrades in the works-
- Detachable handles for the doors so there’s a clear, easy grab point for opening and closing the door
- Adding additional D rings and/or handles to the cart for easier handling during load/unload
- The floor and roof may get some additional handles to give easier, more consistent grip points for load/unload and setup
I’m not going to say you should build this exact arena since a lot of design decisions were based on very specific wants or requirements, but there’s a lot of ideas here that can translate to another arena build with minor adaptation. Feel free to reach out if you have any specific questions.
With that, enjoy.
