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Problem
Problem
Starting March, Mr. Daab told us that we were going to construct a "mini-car" which, similar in scale to our Mousetrap Car, is going to propel itself based on one energy source: this time it was going to be a chemical reaction.
Research
Research
I've had some prior research and experience like when I had done the Mousetrap Car Project and the Pinewood Derby (shown on the right), a cub scout tradition. Both of these projects were closely related to this Chem Car project because they had to do with creating small "cars". Also, since the the car would need to run on a chemical reaction to propel itself, I had to research what type of chemical reactions would be helpful for that purpose, while also being cheap. I contemplated about trying to create a saltwater battery or a lemon battery with a motor, but as it turns out, a vinegar (acetic acid) and baking soda reaction has proven itself to be a reliable option over the past few years, as past students have used it for the Chem Car project, so me and my team ended up choosing the vinegar + baking soda reaction.
Requirements, Constraints, and Possible Solutions
Requirements, Constraints, and Possible Solutions
With my group mates, I purposed the idea of 3D printing the whole car (using PLA) just to make things easy and to get a free A on this project (I over complicated the Mousetrap Car project, so I wanted to make our car as simple as possible). Alas, my group wasn't allowed to do so, for Mr. Daab also specified, after a few days in, that the whole car can not be completely 3D printed.
To get around that constraint, my team and I agreed on 3D printing only the chassis for the car, while creating a top for the car out of balsa wood.
Developing Prototypes! (fig 1)
Developing Prototypes! (fig 1)
I was in charge of making the car chassis in CAD (Computer Aided Design) software, where I designed the chassis body itself and the axles (pictured above) by referencing specific measurements taken by me for the LEGO wheels I was planning to use, along with some donated ball bearings that seemed beneficial.
Developing Prototypes! (fig 2)
Developing Prototypes! (fig 2)
This was the glove I used as PPE ("personal protective equipment") when I was attaching the custom axle of the car to the ball bearings with superglue; I didn't superglue the axles with the ball bearings to the chassis, just in case if this prototype didn't work where I could save the chassis if needed.
The First Problem
The First Problem
It turns out that ball bearings aren't good for a project like this; the axles needed to be "free-moving" so that the car can move as far as it can go with experiencing as little friction as possible. The ball bearings, though, "restricted" the axle's movement, because when I spun the wheels, the wheels stopped moving almost as soon as I stopped spinning them. That's when I learned that ball bearings should only be used in settings where the rotation of an object needs to be controlled because of its low inertia.
My team ended up doing an overhaul of the Chem Car, and I started to CAD up a new chassis.
Developing Prototypes! (fig 3)
Developing Prototypes! (fig 3)
This was a prototype I printed for the axle that worked pretty well, as it can be seen in this image; the LEGO wheel spun much more freely compared to when it was attatched to the ball bearing.
Developing Prototypes! (fig 4)
Developing Prototypes! (fig 4)
This is the CAD model for the new chassis that I designed, in which I had added lightening holes that would make the car lighter and therefore more easier to propel, but it sadly wasn't able to be tested due to it being printed incorrectly the day before my robotics trip. (more explanation below)
The Second (Bigger) Problem
The Second (Bigger) Problem
I had a big robotics trip that was coming up (FIRST 2024 Championship, FRC), meaning that I couldn't be in school while I was going away (to Houston) to compete. The day before I had to leave, I managed to print the new chassis I had designed (which needed some adjustments), but I failed to notify my team members about my new chassis, so they created another car that I didn't know about.
The Last Prototype
The Last Prototype
It kinda sucked, but also kind worked.
My group-mates redid the Chem Car by making it out of cardboard and some thin, aluminum sticks for axles and plastic wheels, most of which were provided by Mr. Daab. (It also like Chick-Hicks from Cars)
By the end, we went with the same kind of design template as our first chem car, only with no ball bearings for more free-rolling axles.
The chassis of the last car I tried to make (the hexagons were borrowed from our FRC robot's design)
Outcome and Reflection
Outcome and Reflection
Turns out we did get some distance in the final testing day; I didn't get to see our "last prototype" car go in the last testing day because I was trying to make another, better car to replace it (inspired by the design of the Robotics club's bot), but I couldn't finish making the car in time in order to test it.
Next time, I'll have to communicate better about new changes and updates about the chem car (we didn't even have a group chat, which in retrospect, was very dumb move), and I'll have to just stop procrastinating in general .-.
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