Since the start of 2228 we’ve been relying mostly on the kit parts and 8020 (a prototyping building material) to build our robots, and I’m starting to see more and more problems with building this way. 8020 is a prototyping material and it allows you to make quick changes and to guesstemate a lot of things and still be able to get it right. Which at first sounds good, but I’ve noticed more and more that because we can do those things we’ve become reliant on them and we don’t design as thoroughly as we should be.
So my question to the FIRST community is how do you guys build your robot, do you do what we do and use 8020 (or a similar material), do you make it out of sheet metal, if make it out of sheet metal do you send the designs out and get parts back, do you make the parts yourself, do you weld your frames out of square stock, what?
I’m trying to figure out what are some of the things we can change to improve ourselves and get an idea of what other teams are doing. The only other solution I have in mind right now is to do something similar to the Thunderchickens (217) and Robowranglers (148).
There’s a poll included in this thread, but I don’t think it will be able to grasp the scope of the differences between teams.
We generally use Bosch-Rexroth aluminum extrusion (very similar to 8020). We use the 20mm cross section profile for just about everything, but we have been known to use 30mm where we need the added strength.
We bolt (or rivet) everything - we seldom use welding if we can help it, since we don’t have the equipment at our main shop.
Team 2410 has been using a square tubing frame since it’s beggining. We ussualy have a polycarbonate electronics board to go along with it. We have been known to use a bit of al plate when needed aswell. (this year was for parts of the kicker and ball magnet complex, last year was supports for shooter and spiral)
We use 80-20. It’s nice, and it lets us make major changes fairly easily.
But we feel that 80-20s holding us back. It might be, it might not. But we’re going to try something new next year. Of course whether it’s wood, sheet metal, some of the sort of hybrid, will depend on many factors.
Our team has used welded box and angle aluminum for our frames for every year we’ve competed, as far as I remember. Our primary sponsor (UTC) usually does the welding for us, as well as some CNC work on the robot, and powdercoating. The CNC is usually used just to create complex designs in the aluminum. For example, our mascots are the 4 Aces, so we usually have the 4 suits (Spade, Heart, Diamond, Club) cut into our aluminum.
2006: Almost completely fiberglass pultrusion, jigsawed to shape and bolted together. Weighed a ton.
2007: Beefy pultruded fiberglass drivetrain. Arm constructed with aluminum tube, with second limb constructed from polycarbonate tube. Sheet aluminum ramp.
2008: Fiberglass/Aluminum plate chassis. All upper structures built with aluminum angle/square stock and rivets.
2009: Almost completely plywood and plumbing supplies.
2010: Almost completely welded steel tubing. Plywood electronics board.
Our most successful year: 2009, by far. (yes, the wood and plumbing one)
The biggest thing I’ve learned through these variations is that there is no universal best material to use for building a robot. Our material selection was based heavily on what the robot had to deal with for each year’s particular game.
The other big factor that comes into play is the short time you have to build and test your robot over the 6 week build period. It is crucial to get things built as fast as possible. We were so successful in 2009 because our sponsor’s shop (IEWTD) is loaded with heavy duty woodworking tools and we were able to get things built quickly. Build to your strengths!
That said, my favorite materials to work with are plywood and steel. Both are relatively easy to deal with, cheap, and fast to work with. I would never use 80-20 style extrusion for structural robot parts since it’s the wrong material for the job. Use what works for you.
It’s been sheet metal since day one for 2815 (and, this season, 1398).
1618, for my three years with them, met with the most success using the kit frame and angle aluminum construction. (There was the PVC pipe structure in 2008, but that was ultimately mostly for holding up the side panels and flag holder.)
1293 has been mostly sheetmetal over the years, with 80/20 in a supporting role where it made sense. (They’ve been known to bolt their two drive pods together with it, then attach their superstructure to it, or for a lift mechanism.)
330 uses the KOP frame… for prototyping and code testing.
For the competition robot, it’s always been either box or angle aluminum for the drive frame, and then angle aluminum/box aluminum for the superstructure, with the occasional dose of PVC or fiberglass pultrusion in the manipulator area.
I’ll let someone else from 1714 talk about the robot. I tried to figure out what they made the 2010 one out of but I couldn’t see it.
If all goes to plan, Shaker will have built 3 robots with 3 completely different materials. In 2009 the robot’s frame was made of pultruded fiberglass. I-beams with cutouts for wheels made up the drivetrain, c-channel all around for bumper mounts. Some aluminum channel and box tubing for the tower, a fiberglass intake, and then lexan for the rest. Pretty cool.
The 2010 frame was made up of 4 1/4" aluminium sheet as side rails, assembled with standoffs. Some 80-20 connected the sides together and formed the rest of the frame. The bumper mounts were a bolted on rectangle of pultruded fiberglass.
We start with the kitbot frame (it may be heavier that some other solutions, but it’s the quickest thing we can get going, and it have everything you want in a frame). From there, it’s pretty much all sheet metal and angle stock. We usually end up having the machine shop at our primary sponsor do a few small things for us (lightening holes or complicated patterns), but 99% of the work is done in house, by the kids.
This year 397’s robot was quite literally 2 KOP frames stacked on top of each other. We used 80/20 in between them. This made our frame quite heavy but incredibly rigid. It also gave us the benefit of letting us play with the mounting height of our kicker until we liked it by sliding it up and down.
In the past we have used the KOP frame and 1" square tube to build the robot. We bend the tube in house using a standard pipe bender. This can then be bolted together (or welded). The only time this method was a problem was in 2008 when the force of the launcher changed the shape of our frame as we fired. I’m sure someone has a picture of 397 hitting their frame with a hammer to make it go back square. I personally like the bent tube construction method. But as always, you work with the resources you have.
In years 2005-2009 we used the kit frame and aluminum angle and box for the other assemblies. In 2008 we used a smaller version of 80-20 on the speed racer robot and had some 1x1 80-20 in the upper frame work for our 2009 robot. This year we decided to use 80-20 for our robot frame as it was great for prototyping, moving stuff around, and very, very strong. However like many teams it ate up weight, parts shifted (a lot), and was a hassle when we ran out of sliders and brackets. Team 234 said in their swerve drive implementation conference that 80-20 is a great prototype, but aluminum box is better for the final as it is lighter and parts don’t slide around.
I hope our team uses more aluminum box in our construction to help save on weight and parts moving, but a strong rigid frame was desired in our first meetings of the season which 80-20 accomplishes until parts move around.