Hello!
Team 395 is interested in building a new cart for our robot, and we were wondering if anyone has any advice that would help us design it. Our old cart is very bulky and difficult to maneuver and we’re looking to make something new! We’re also looking to make this into a project to get familiar with design/machining so we would like to add some element of “home made” to it (aka not just buying something…potentially buying something and building off of it?) Any ideas would be appreciated!
What has to fit on there, in addition to the robot? Driver station? Spare battery? The other bumpers? Tools? Gloves? Safety gear? Some emergency hardware, for when your freshman human player drops the bumper pins?
How big are the doorways in your shops and at events? Does your pit have a front clearance that might require a change from your usual cart to a shorter cart so a tall robot can fit? Do you have any space limitations in your truck/bus/van/trailer/whatever-gets-your-gear-there? Do you have to clear any particular terrain? (Spoiler on this one, yes you do, strongly consider big air-filled wheels or you’ll be fighting every cable protector you see.)
Once you know how the cart fits into your system, I think you’ll have a better idea of what you need to change.
(Also, this post was partly to plant 4451’s carts in your psyche. )
Harbor freight 8" solid rubber (not pneumatic) castors and wheels. Two locking casters and two none swivel casters. Pneumatic tires can have blow outs at events or get flats that’s really annoying.
Going back to what Billfred said, it is very important to understand your team’s exact needs. With robot carts, it typically isn’t a one-size-fits-all type of solution.
Obviously, making sure you know what you want to store in the cart is crucial, but keep in mind that generally, the simpler the design, the better, so long as it meets your needs. I was initially planning on having our robot cart hold a bit more than needed, however, this would have resulted in issues for us, as the cart would have been difficult to move around with all that extra weight.
For our team’s robot cart, we used a document to lay out the things we actually needed and anything that was desired but not necessary.
Here’s an image of our robot cart for reference: https://imgur.com/Oip1hDR
For most of the aluminum tubing (the only exception is the horizontal 2x1 tube on the back) we went with 1/8" thickness to support quite a bit of weight.
On our gussets, we went with 0.09" gussets for everything except for the gussets used to mount the casters (0.25"). We went with 6" casters (2 swivel, 2 static), although bigger wheels would probably make the cart a bit smoother.
We’re still adding onto our robot cart, but this design has worked very well
for us so far, and was actually quite simple to assemble.
Also design the top of the cart so it can be changed from year to year and it holds the frame. With the wheels free you can test the drive train in the pits.
We just went through this exercise. After thinking about it for a while, we actually went to something a little like Spectrum’s cart. We decided that the lighter the cart the better. Excess weight poses difficulties in maneuvering around small spaces, and makes it hard to push on carpets and foam pads. We see both those during the season.
Our cart uses 6 inch wheels. I would absolutely not go any smaller than that. We carry an absolute minimum of tools on the cart. The tools are usually limited to a set of hex wrenches, some zip ties, and a wire stripper. We have room for a couple full batteries and an empty. We also have an inverter and USB plugs attached. The top of our cart is usually a couple of 2x6’s that we change out every year to “tailor” the cart to the robot. There is also a little room for bumpers because there are matches have short turn-around and you need to change bumpers and batteries without returning to the pits.
My favorite robot cart I’ve used is the one my team built this past year. I wrote about it here.
It’s useful for multiple years’ robots, as it can both be tall (for short robots) and short (for tall robots). It also features a control panel shelf and small tool cabinet near the handles, which I forgot to mention.
When my son and I were with DiscoBots, we built a light, flat-deck cart. It was light enough, that it could be flipped upside down and slid in over a bunch of totes in the back of my SUV.
To get the height, we just put an empty tote on the deck and sat the robot on it. When the robot was really tall, they didn’t use the tote.
I would go with something low enough so carrying the robot off the field is quicker and efficient. I’ve seen other carts that were high and it was hard to get the robot on it as it needed to be lifted higher.
I’m from Team 5740 and we are looking for a new robot cart, our budget is around 200 dollars and I’m having trouble finding a cart for the regular dimensions of the chassis and has maybe a shelf or some drawers for storage. Does anyone have suggestions for a cart that would work?
Several years ago, we got a garden cart with pneumatic tires, from a local builder supply. Every year we add a small wood structure to the top of it, that the robot will fit on and not slide around. Our Technician is working on finally adding a drawer under the cart, to store tools.
Another consideration on the cart is getting it to/from competition. We don’t bring a lot of stuff, and I usually end up hauling it, so the more compact the cart, the better, as far as I’m concerned. Our garden cart is a bit bulky, we ended up having to remove the front axle to fit everything in my new/used Tahoe this year.
We have a cart whose base is basically just one of those dollies you’d get from Home Depot or somewhere. In the center we’ve got a raised rectangle made of metal pipes that the robot rests on and is narrow enough that the wheels hang over. Around the edge, we’ve got another, lower railing of sorts made of pipe that’s just far enough from the bit for the robot that we can store spare batteries in the gap. Our handle is also made of pipe and looks like what you’d see on a shopping cart. I imagine you could build something like it with your budget
We use something like this with a large heavy-duty plastic tray attached to the table and pieces of wood attache to that that the robot can sit on without the wheels contacting anything (for testing). The wood pieces tend to change for each years particualr robot. The tray can hold whatever’s needed- parts, tools etc. We like it.
An Idea I would do, make it out of 80/20 because it is structurally strong and also if you need to get to the top of the robot you can stand on it as long as you build it strong, the robot cart we have is like this, yes it is the biggest cart at every competition, it is also a cart that some people loved to see. It does have some flaws from my experience as technician but those are simple repairs. The 80/20 on our cart is double stacked to provide the most strength and be able to support anything, you can throw a large toolbox at it throw a robot on it and hit it with a car thing’s indestructible. Yes it is heavy but that is from the strong materials it withholds and items it holds. Now some basics to improve your design, yes, you will want the same structure, but make it so that you can fit through competition doors if you have no problem going through loading docks instead of regular doors, generally our robot can’t fit through the door anyway without taking bumpers off and rolling it/carrying it this is why we have a big cart. If you can build the big cart without the problem of standard doors at your shop and the competition you’re good to go. if not, make it as wide as you possibly can as long as it fits in your pit, trust me it will be so much better for your technician and pit crew. Also, the only two non-team built thing you’ll need, the biggest toolbox you can put on the cart so that your technician can carry the essential needs for the competition.If you can fit this on your cart it will be a lifesaver when looking for tools, duct tape, documents, CADs anything for the technician when repairs are needed. Although it is expensive, a 26" toolbox will do the job even if you find another one you like instead. Also another thing you will want although obvious is a place to store your bumpers and your drivers station, you can lay bumpers on the bottom like our cart which fits in just right side to side or you can build a rack on the back for bumpers where the handle is. It’s all about storage and what your technician needs, and your driveteam needs. A great thing to do is extend the length to be able to carry your drivers station or you can keep it short and the driver/operator can carry it themselves, I’ve seen lots of ways to do it. But in your case, I’ll break it down for you. You will need these features for your cart.
-Structurally strong
-Carries a toolbox
-Carries bumpers
-(optional) carries drivers station
-Big enough to carry what you need small enough to fit through a normal door if you can’t avoid them.
-Two fixed stands that extrude from the top of the cart to hold the robot up (Do not build the stands out of wood)
Materials you will need to recreate this kind of cart is
-80/20
-Plywood (big enough to fill the entire cart not just pieces)
-2 fixed caster wheels on the back 2 swivel casters on the front, like a shopping cart.
-Some 1/8" sheet metal may be required
This is a quick easy build you can get done in a week and fancy up if need be, remember the bigger your cart can be the easier it will be, yes it is heavier and takes a small distance to stop but any handmade cart like this or any seen at competitions for long term use does have a stopping distance I highly advise you to not use ropes as a handle bar,it may seem much but it is easy to use for our team and i’m sure it’ll be easy for you. I’d like to see pics when you’re done though! I love seeing handmade carts!
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