Adjusting my car's cup holder to fit a standard cup
Key Skills
Sketching
CAD Models (Fusion 360)
Laser Cutting
Experimentation and Iteration
This is the first project in my DIY Design & Fabrication class at Carnegie Mellon University. The task was to ideate and then develop an a accessory that would enhance the coffee-drinking experience, either using a personal mug or a standard paper cup. The solution was intended to be specific and individualized. I don't drink coffee very often unless I have a morning interview or a very early start at work. Unfortunately, getting coffee tends to makes me run a bit later than I had hoped, as the mood board above shows.
I chose to create an attachment to my car's coffee cup holder because I have had trouble using it effectively since it is not adjustable. As a result, there is too much "wiggle room" and cups often slide or tip as the car is moving or turning. Smaller cups can also be hard to pick up when they are full because of the width of the holder. I had also been considering a clocked-shaped coaster or decoration where the user would place the cup in the appropriate slot as they felt a reminder not to drink too much coffee very often, but decided that I would have more use for the car cup holder attachment. Some of the earliest sketches are shown below:
Brainstorming sketches
The catch was that the item could only be made out of acrylic sheet using the laser cutter for forming shapes and engravings. I started by sketching some simplified options, such as these:
Cup holder sketches
We were covering freehand sketching techniques during this part of the project, and while I improved throughout the project, I did use tools once the sketches were ready to become drawings with dimensions to be modeled. Meanwhile, I went to my car and took measurements of the cup holder. Because I did not have a caliper on hand, I found it easier to use a combination of ruler measurements and simply cutting out construction paper and placing it until it was a press fit. I also experimented with different handle shapes. This process is shown below.
Progression of construction paper mock-up
I also noticed that the divider between the two sides could be very useful. I had previously been taking measurements with a press fit in mind; however, by wrapping the accessory around the back of the lip, it would eliminate degrees of freedom during travel without requiring such high precision. Thus, rather than have the accessory sit on top of the lip, I used the sunken part to determine the planar height and corresponding shape.
In addition, I found that the flimsiness of construction paper made it difficult to get the mock-up to stand on its own, so I switched to foam core and cardboard that I could cut, with similar thickness to the 1/8" acrylic sheet that I was planning to get (3/16" and up felt too bulky).
Evolution of foam and cardboard proof-of-concept
The 3D model was made in Autodesk Fusion 360, converted into a .dxf file, and sent to the laser cutter. I then used a heat gun to bend the acrylic. This was the most difficult part, as I knew that although I had taken an estimate to account for varying handle heights due to inconsistent bending, it still had to fit in the car. I ended up using the first one as practice, and made small changes to the model after placing it in the car to test the fit. I also chose to go with more rounded bends on the handle after I noticed that the cup holder and surrounding interior had very few right angles. The model, first prototype, and second prototype are shown below.
Fusion 360 model
First prototype
Second prototype
The final product works fairly well, as it is a much better fit for the standard paper cup as well as a Carnegie Mellon thermos coffee cup. The color matches the cup holder well, and is dark enough to hide a coffee stain or two. I had the engraving placed so that when I take my cup out when I get to work, I see an uplifting message. The weight of the liquid helps to press the top down and keep the piece flush to the cup holder. Still, the fit could be a bit better, and the top could be elongated so that the hole is directly over the message. Even so, it was a good introduction to working with the laser cutter and a heat gun.
Concept from sketch to prototype
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