the team I am on is still relatively new, we have been using the same stock material, 80-20, for basically everything we do (with a few exceptions). While 80-20 is a great material it can still be limited, bulky, and harder to work with. This year we have access to a cnc machine, lathe several mills, and a 3d printer, so we are especially interested in how we can fully utilize those tools.
What materials do other teams use or buy a lot of to use with their robots? I am especially interested in what some of the teams that regularly go to nationals use. I see some pictures of teams with early versions of robots constructed mostly out of 80/20 but then the final version seems to be something else entirely.
For our frames, we use 1" alum box tubing (1/16" walls I think), welded into shape, which leaves an unbelievably strong and fairly lightweight piece. It is difficult to work with though, so I would not recommend our approach to a team just starting into the wonderful world of manufacturing.
On pieces that require utmost strength, like drive-train brackets and our climbing plate, we use 1/8" aluminum sheet metal, laser cut from CAD drawings and bent with a brake.
Depending on other applications, we use thinner and thinner material.
For our hopper, we used .0404, as it is very lightweight and easy to hand repair if we bashed it up a bit. For our main shooter body, we used 1/16" aluminum, which is slightly thicker, because of forces related to accelerating a Frisbee.
I think in 2011, as part of our gripper, we used .0202, but that stuff is basically paper.
For electronics, we bought a large sheet of corrugated plastic (basically plastic cardboard). You can poke through it with a screwdriver, and it is reasonably, but not uselessly, flexible. It is also very lightweight and easy to manipulate with hand tools. (on the cRIO plate in picture 1, we used a polycarb sheet for more strength.)
Your number one material will most likely be aluminum. Square tube, round tube, angle, sheet from 1/16 to .25. Then plastics (mostly sheets) UHMW, lexan, and polycarbonate are our main ones. Delrin (acetal resin) is commonly used as a bearing surface (I also like white UHMW for this). All of these can be cut on the tools you have. Also don’t count out 80/20 it can be more expensive but it can be worth it.
I would advise using the 3d printer for prototyping but not anything structural.
Here on 68 I’d say aluminum is the material we use the most. We mainly use 2X1’s .125" in diameter, and 1X1’s .0625" in diameter (we do occasionally use .125" 1X1s, but not .0625" 2X1’s) for anything structural (chassis and supportive pieces). We’ll use .0625" and .125" sheet in addition to various sizes of angled aluminum for less structural things (like the functional/moving parts in our manipulators… such as what pushed frisbees into our shooting wheel this year, and the tube that held them). There are some custom .325" thick plates in a couple places on our robot that we sent out to be water-jetted (mostly on our transmissions). We also used some Diamond Plate on our driver station and robot cart…
I’ve also noticed the use of lexan sheet in a lot of different places (such as the base for our electrical board, sponsor panels, guides for frisbees to fall into our disc-holding tube, and the outer wall of our shooter). I’d say that is the most commonly used material other than aluminum on my team.
As for your newer question about the use of a CNC mill, we mainly use it to accurately mill out lightening holes in chassis pieces and driver’s station (only on 2X1X.125").
What kind of CNC mill do you have acess to? A decent sized machine can be used to machine almost every part on your robot. Based on your resources, I would reccomend using a combination of 2"x1" and 1"x1" aluminum box tubing. Look at teams like 254, 973, and 1538 for great examples of how to use these materials.
Virtually every part on our machines is cnc milled. We use a lot of 1x1 and 1x2 tubing along with 1x1 and 2x2 angle for brackets and the like. For sheet material we mainly use polycarb and it too gets cnc milling. For milling the polycarb sheet we use double stick tape to attach it to a sacrificial piece of particle board that gets clamped to the table.
We also use the 3d printer for a number of things. We’ve used it to make gears for driving encoders and we use it to make pulleys for polycord loops. They basically have a 1/2 round indentation and slip over a piece of aluminum tubing. There are little tabs on each side that we use to rivet them to the tube. Those do a great job of keeping the polycord running right where we want it. We also printed a cover for a ratchet mechanism we used for our climber which had particularly sharp teeth. We incorporated a 3d version of our bear head logo on it for decoration.
A tormach cnc milling machine. Not sure what the exact table size is but it is definitely a high quality machine.
We also have access to two grizzly mills. One is a hobby/desktop mill and another is a more professional 7 foot tall mill, also grizzly. There is also a broken bridgeport mill and grizzly lathe.
Wood. Bends, before it breaks, flexes back into shape. Light weight. Plentiful and cheap. Fast curing epoxy can repair most breaks. Home depot or Lowes near most competitions.
That is a bit on the small side, but still better than nothing ;). With a CNC of that size, you can still do almost any custom gearbox, all your gussets, half of you box tube, and a lot of your misc. parts. The rest should be able to be done on your other equipment.
Here are some great albums showing detailed photos of 254’s 2012 and 2013 robots. I would start here to find ways of incorporating your new equipment into your manufacturing process.
As others have said before, the materials that you will find yourself using most is 1"x 1" box tube, 2"x1" box tube, 1/8" plate, and 1/4" plate
We like to use a lot of aluminum, like the teams that have responded above for many of the same reasons.
One of our favorite materials, especially in the past few years, has been HDPE. This is the material we made our shooter out of and we really love it. It is fairly easy to machine and deal with. Obviously, it’s not good for structural elements, but it can come in handy for a lot.
Major downside is that it can sag under its own weight. We ran into this as our shooter began to droop towards the end of the season.
We’ve used all kinds of materials…steel, aluminum, fiberglass, wood, polycarbonate, carbon fiber…
And we generally build all of it without using any numerical control equipment. A band saw and drill press, tin snips, circular saw, jig saw, hack saw, and cordless drills will do it all.
It’s good to see that you figured out that 80/20 is not a very good robot building material.
Besides the materials already mentioned, 449 tends to use a lot of delrin for many different applications. It’s relatively light weight and extremely easy to machine. It is also relatively slick, so you can use it as a makeshift bearing block for low speed purposes.
Last year we did a west coast drive style aluminum frame with sheet metal inserts. It was 1x2" aluminum box tubing 1/8" thick and 1x1" box tubing 1/16" thick. Our belly pan was 0.090" thick. Our climber was 1/8" sheet metal. I forget when steel we used in the climber but it was 1/4".
this year wear going heavier into sheet metal. We are back to having more sheet metal resources than welding. So likely most of the robot will be 6000 series aluminum at .125 , .090 and .060" thickness. to avoid welding, we will be machining and cutting gussets to hold any 1x1" box tubing we way use via rivets or screws. We had some good luck with ABS bearing blocks last year, so we will continue to use that. We makes ours thicker so they are for applications were a very thin aluminum block is not practical. We will also being making our larger gearboxes out of machine 1/4" aluminum. Our smaller boxes will be 0.090" aluminum sheet metal likely. A few other material we may use include Acetal, HDPE and PTFE. We may get into machining a few shafts with 7000 series aluminum, whatever we can dig up at the scrap yard.
449 just made the change from predominantly 80-20 frames to 2’‘x1’’ aluminum tube (and good riddance to the 80/20, it’s a terrible material that breeds bad habits and should only be used for prototyping, in my experience), assembled with match-drilled gusset plates and 1/4’’-20 bolts. Easy to do and very sturdy.
4464 this past year used the standard kitbot c-base frame, with a superstructure of aluminum tube of varying sizes and riveted gusset plates, which worked great.
I fully agree with you there. Our past two robots (the first one doesn’t count, it was our rookie year) were basically tributes to the company that made 80/20. The robots were almost entirely made out of 80/20 and were barely able to be finished within 6 weeks.
One of my goals for this year was to make a prototype 80/20 robot (to some degree) in 3 weeks, then remake everything better the second time around. I have found that testing the robot for only a day or two without any field components has left our robots with many hidden problems. With a lot of machines and more supervision, it will be a lot easier (hopefully) to make better robots in shorter time.
Whatever material you decide to use, make sure to experiment with it before the season starts. A robot made out of 80/20 that can play the game is better than spending 6 weeks trying to figure out a new material and not having enough time to refine your design. If you’re barely finished your robot last year in the 6 weeks, make sure your team this year is able to be competitive before taking on additional challenges.
Quoted for truth. Resources means experience as well as material and capability.
As I have said before, 341’s 2012 robot is one of the best, if not the best, Rebound Rumble robots. They finished the season seeding first at EVERY SINGLE EVENT they went to(including IRI and CMP), 87-9-1, division finalists, and IRI finalists. They maximized their resources, using what little resources they had only where they needed it. I love using box tubing because we have the machining resources necessary to fabricate with it and it permits us to build extremely light robots, but 8020 can be just as good if you need to build quickly with little resources.
