Build Material Question: 8020 vs. Box Tubing

Hi everyone,
My team (834 the SparTechs from Center Valley, PA) has been using t-slot extrusion (8020) for around 10 years at this point. While in 2010, 8020 was common, but from 2014-2019, I’ve seen more and more teams use box tubing. Seeing this shift (albeit after many years) we have some questions:

  1. Do you believe that (in 2019) teams should still be using 8020? Why or why not?
  2. What building materials do you teams use? How has it been treating you?
  3. Do you have any experience switching from 8020 to box tubing and how has it gone?

3284 has used box tubing of some sort every year since founding, and having messed with 8020 for prototypes and other small projects we have chosen to continue using box tube. This is a simple choice for us for a few reasons. First, its much lighter with comparable strength in certain alloys. It also is easier to machine custom features and details in due to the simplicity of the extrusion. Its much cheaper at roughly $3 a foot for 1/8 wall 2x1 box tube. It is just as simple if not easier to machine due to the wide range of gussets offered from VexPro and TheThriftyBot to make riveted assembly easier, or you can choose to weld as we have. 8020 using only the slots allows the profile to shift under impact and loosen over time. The major FRC vendors are designing components around integration with 2x1 tubing and this is a big factor in itself. Overall for any application on a robot, we would choose 2x1 or 1x1 box tube over 8020 and advise others to do the same

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  1. 8020 has many uses but has always been marginal in FRC. The shift away from its use as a primary robot material isn’t because of what is cool, it’s because there are several other options that work much better and always have.

  2. We currently use box tubing. We started using it exclusively in 2014 with the advent of versa products but quickly moved to making our own gussets and drilling holes in standard stock. It works great and we probably won’t ever have reason to switch away.

  3. I think we only ever used 8020 to build the enclosure on our CNC router table, for which it worked fine. We experimented with wooden robots (at least 3), polycarb robots, old style kit frames, even steel construction frames, and I like what exists for teams today. Box tube, sheet metal, gussets and welding.


8020 is good for very particular situations, like if you have a very large stock of it and can live with the extra weight. It’s also a good prototyping material (with caveats). You have to make sure that what you prototype is applicable even if the final material used to make the mechanism isn’t 8020.
Where box tube really starts to shine over 8020 is on moving things. Especially on elevators, the extra weight of 8020 is killer. The bearing setups are never as clean as they are on 2x1 box tube, and the extra mass makes everything that much harder to move. Plus, the screws inevitably start to shake loose, so you have to check your screws periodically to make sure nothing has come apart.
If I was starting with a new team, I’d do 2x1 and 1x1 box tube. Much lighter, pretty easy to work with, and no sliding around (except when you want it to). I would only use 8020 if my team was very budget constrained and had a lot of it left around, along with associated gussets and brackets. But the relative cheapness of 2x1, combined with its workability, makes it the clear winner to me for most teams.
That being said, it’s a little close to 2020 to switch over the box tube entirely, although if the game needs another elevator or arm, it might be worth using just for those subsystems.


3946 used lots of 8020 in the rookie robot, and had to do a lot of drilling on that Mardi Gras evening in 2012 (Bag day was Mardi Gras that year) to make weight. There were very few places we really used the adjustable slots. (I wasn’t officially a mentor yet, but I was there; I suspect SHS room 610 still has bits of swarf from that night.) Since then, construction has been based on angle, channel, and tubing, and the only time the team has been anywhere close to the weight limit was when we tried (unsuccessfully) to “do it all” in 2018, and had to leave the ramp off.

If you’re using 8020 and OK on weight, then carry on. If you find that you use the slots for adjustment during prototype but have weight issues, consider using 8020 for the prototype phase but converting to tubing or other stock for the competition version. If you don’t use the slot adjustments, why deal with the extra weight?

Your friendly neighbors down the road could definitely shed some light on this subject for you! You guys out of any team know you’re welcome to the barn whenever.

The largest reason for moving away from 80-20 is its poor bending resistance to weight ratio. The area moment of inertia (the value that correlates to resistance to bending) of tubing is significantly higher than that of 80-20 type products.

  1. I think there are many good use-cases for 80-20 in FRC robots today, but that same design can almost always be done lighter and stronger with other material. Systems that need a lot of adjustment thrive with modular building materials.

  2. We use almost exclusively square and rectangular tubing with some round tubing/conduit thrown in in some places. It’s been fantastic in terns of availability and usability, though stuff like versa can definitely be a bit on the expensive side for what it is (though comparable to 80-20).

  3. In 2009 we switched from an almost entirely 80-20 bot to round titanium tubing thanks to a sponsor. We used titanium round tubing structure from 2009 until around 2015 where we switched to aluminum square/rectangular tubing. Throughout those years we had many use-cases of 80-20, but our primary structure was always tubing. We will probably move more and more away from 80-20 as time goes on.

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Our team has never used 80-20 but I can speak for box tubing.
The biggest advantage imo is that you can drill bearing holes into it. This is great for mechanisms and you won’t need an attachment as you would with 80-20 to mount bearings.
The other thing is finish. Recently our team has been powder coating our robots and powder coating 80-20 would render the slots useless.
We have never used 80-20 but I am assuming you would have to buy special nuts and what not in order to join pieces due to the slots. Since they are slots, with a hit hard enough something could shift as well.
Box tubing is likely much lighter as well since it’s cross section appears to have less material.
We’ve likely never used 80-20 simply because we probably didn’t know it existed or it was simpler to use box tubing.
As a final note, it looks cleaner and you can route wires, tubes and other stuff through it.

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We made the switch from 8020 to box tubing last year. Couple things to note:

  1. It’s easier to change a design on the fly with 8020. Being able to loosen a few bolts and slide things around late in the build process can come in handy, especially if your team doesn’t plan or use CAD much.

  2. Our weight problems became a thing of the past after we switched. Our robot last year weighed in at 78 lbs without the battery and bumpers.

  3. Versachassis with gussets is faster to assemble than 8020 especially if you’re using rivets. We always spent so much time messing with sliders and alignment with 8020. This math changes significantly if you’re buying raw box tubing and machining the holes yourself.

  4. Assembly of 8020 takes even longer if you loctite everything, because bolts WILL come loose over time if you don’t use loctite. It was almost strange for us this year to open the bag and not have loose non-loctited bolts in the bottom that worked their way loose during transportation.

  5. We’re glad we still have 8020 around for prototyping

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We’ve used various box tubes since our inception. It’s been a pretty strong choice although I can see the benefit of 8020 for quick prototyping. I don’t think I would use 8020 for a comp robot as it seems to bend under less force than box tubing.

We use 8020 for prototyping and box tube on the robot. 8020 is heavier and tends to loosen up over time, so I don’t think we’d ever put it on the robot. It’s great for the middle stages of prototyping though, when you’re tinkering with angles and positions and need more quick adjustability than you can get by drilling holes in box tube.

1712 extensively used 8020 for many years. We started using more 2x1 box tubing in our drive train around 2015, and have been using less and less 8020 on our robot in each year since then. We only had a few small 8020 pieces on our 2019 robot.

8020 still has its uses in specific applications. For teams that can’t/don’t weld, it’s great when you need to thread into the end of a structural component (something you can’t just use a smaller stand-off for). 8020 also has a large ecosystem of associated components, some of which can integrate quite nicely into niche applications.

8020 is also great for teams that don’t have a highly developed CAD/design team and teams where the border between prototyping and robot construction is blurred. It allows for a lot more variability and testing before you lock in dimensions. And use of proper fasteners and thoughtful places to drill through the extrusion can still lead to well-secured final dimensions (albeit with a lot of load placed on your fasteners).

Box tubing is far and away a lighter and more effective option… assuming you have a robust fabrication process that can make holes in tubing and make gussets to join them together.

Accurately placing holes in box tubing and cutting out gussets is relatively straightforward if you have the right tools. But without a mill and/or a cnc router it can be difficult to do quickly.

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