Large-Scale Steel Fabrication
FRC Field Perimeter

Image of field perimeter for FIRST Robotics Competiton

A full-size field perimeter built for FRC, assembled in mild steel sections

Summary

This is a work-in-progress project. Ever since my first year competing in FRC, having a full field to practice on has been something of a pipe dream. This year, the stars alligned, and we were able to rent a large enough space to fit it. The task of building the perimeter fell to me, and I wanted to create something that would last 10+ years.

To do that, I drew on my experience with my go-kart project to make something really robust. I based the dimensions of my design off of the official field, but I started from scratch design wise. Optimizing for simplicity, part count, and transportability, I ended up with a design that uses many identical sections and can fit in the bed of a pick up truck when dismantled. I designed the field in Onshape and the CAD is available here.

Image of field perimeter for FIRST Robotics Competiton

The 6 "driver station" segments split into a base and a window, and each of the wall sections split and can be stacked. Each section gets bolted to the next with 3 5/16 bolts, and most of these joints also get a bent steel "foot", which was ordered from an online laser cutting service. These get velcro on the bottom, which sticks to the carpet.

The shelves are designed to be made from 3/4 birch plywood and even have some cable grommets to make charging laptops or other devices easier. Field walls are skinned with 1/4 polycarbonate (lexan) and self-drilling screws. Finally, the door sections use some extra welded plate steel elements so they can slide out.


Fabrication

Cutting, drilling, welding and grinding all of the sections proved to be a monumental task. Working with several 8033 members and parents, we completed the work in several weekends in a welding shop on treasure island. A few things there helped hugely to accelerate the process.


Me operating a prototrak vertical mill

The first was this Prototrak mill, which has steppers and a conversational interface. I set up a stop and waypoints for each of the holes on the pattern, and since I designed all my 5/16 holes to have a consistent distance from an edge, this single setup was enough to drill all of the tubes over the course of a couple days.


Stacks of drilled steel box tube

This was the first batch of steel tubing after deburring the holes. There were two more of these for the whole field to be completed.

The next major thing that helped accelerate the fabrication was this crazy Siegmund weld fixturing table. This enabled us to do setups for all the sections and weld directly.


Welding table with setup
Me welding on the setup table

After all of this was complete, the doors were welded seperately with some clamps. Bit tedious, but got done quickly.


doors setup with clamps to be welded

And yes, it did indeed all fit in the back of the truck once grinded and finished.


doors setup with clamps to be welded
doors setup with clamps to be welded

Next Steps

After completing a dry fit of all the parts in the space, they went off to be powdercoated at Leon's in Oakland. When they came back a week later, powdercoated in military beige (the color of free!), they were once again transformed.


truck bed full of powdercoated sections

Having completed all the powdercoating, the polycarbonate was also back from CNCing and everything was ready to integrate. I took it to my Scout Hut (the troop has off time during the holidays) and prepared for final integration.

stacks of sections and lexan inside scout hut

Skinning the walls

Have any of ya'll ever used self-drilling screws? Well then you know they suck! Though I knew that during the desgin process, I could have never expected what we were in for during the almost 9 hours it took us to integrate everything.

Working with a team of several people, we ended up having to pre drill all the holes in the steel, using the polycarbonate sections as a drilling template. The sizing here was incredibly precise. 3/16 was too large, and 5/32 too small. Using #10 self-drilling screws, only an 11/64 hole would create a reliable tap. We also used cutting oil, which further helped reduce the chances of snapping the screws.

finished door section with lexan inside scout hut

Finally, we were in. After self-drilling and oiling, everything went smoothly. We also cut and drilled the 3/4 inch plywood for the driver station sections and drilled a 2 3/8 hole for some cable grommets.


finished door section with lexan inside scout hut

Getting it all assembled

The last step here is to integrate everything in the final space. This has been an incredibly large project and I'm super proud of how it came out - especially the little details, like the cable grommets and rubber plugs pressed into the exposed tube ends.

I'll make sure to send an update here when we have it all together. Thanks for reading!