ME360 Project #5: Cup Crusher

This project aimed at designing a Closed Loop Control System utilizing PID control. This system provides a continuous variation of outputs within a control loop feedback mechanism for enhanced accuracy and efficiency.

Within a team of 4 Mechanical Engineering Students, I created a cup crusher that adjusts its crushing speed and torque based on the weight of each can placed under a pressure sensor. The corresponding signals are sent to stepper motors, which spin the vertical crusher according to the detected weight.

Design and Development

Pictured below is our initial sketch of the cup crusher:

Initial Sketch

The initial concept for the cup crusher included an elevated base that would rotate at an angle of approximately 45° using a servo motor, allowing the crushed cup to slide into a container. However, this container feature was deemed unnecessary, and so the design was simplified to focus solely on the crushing mechanism.

The final design used 80/20 aluminum bars for the base and a 1/4" acrylic piece for stability. The crusher itself comprised a long aluminum bar and a square wooden plank, with the aluminum bar adding necessary weight and balance.

A picture of this final design is shown below:

Final Build of the Can Crusher

We created the base using 80/20 aluminum bars and a 1/4" acrylic piece, leaving gaps for the stepper motors and threaded rod system. This system includes two threaded rods, couplers, brass nuts, ball bearings, and shaft collars for smooth rotation and torque, with various 3D-printed attachments connecting to the 80/20 bars, which we designed on SolidWorks.

The crusher itself is composed of a long aluminum bar and a wooden plank. Initially, we planned to use the wooden piece alone, but it proved unstable for vertical crushing. Adding the aluminum bar provided needed weight and balance. We found that crushing the cup horizontally was more effective than crushing it vertically.

Manufacturing Process

The manufacturing process involved several key steps:

3D Printing:

• Bearing Backet Mounts: We used the FDM Printers within the BU Mechanical Engineering Department's 3D Printer Room to print out the 80/20 mounts that held the bearing brackets used to smoother the rotation of the threaded rods.

• 90° 3-Hole Angled Flat Plates: We also 3D printed plates that would connect the base 80/20 bars to the top bars.

• Breadboard Mount: We used a small breadboard for the wiring, and made a mount for it to attach to the back 80/20 bar.

• Motor Mounts: These were meant to hold the stepper motors in place relative to the rest of the crusher.

Laser Cutting:

• Wooden Plank: Following the 3D printing phase, we laser cut the 1/4" laser-cut wooden plank using an 80W Epilog Fusion Edge CO2 laser cutter.

• Acrylic Sheet: We also laser cut the acrylic base where the cup is placed on. We made a small gap to facilitate sliding the base into the 80/20 bars, as well as to allow space for the stepper motors and threaded rids

Crusher Assembly:

• Integrated two threaded rods, couplers, brass nuts, ball bearings, and shaft collars for smooth rotation and torque.

• Used the 3D-printed attachments connected the stepper motors to the 80/20 bars.

Final Adjustments:

• Added a long aluminum bar on top of a laser-cut wooden plank to enhance the crusher's weight and balance, as well as to position the cups horizontally for more effective crushing.

Simulation and Testing

Shown believe is a video in action of our functioning cup crusher (featuring a lot of squeaking from the nuts and collars 😂):

Showcasing of the Cup Crusher in Action

As you can see, the crusher is crushing it!

Conclusion and Recommendations

To improve the cup crusher, we would:

• Use more efficient motors (e.g servo motors) to provide greater torque and electrical power that might even be able to crush cans and not just cups.

  • Throughout our testing phase, we found that our crusher was unable to crush aluminum cans regardless of their diameter because of how much heavier and sturdier they were. This was actually our original goal, but also the reason we switched to just cups

• Employ finer-threaded rods to facilitate smoother rotation and reduce friction-related noise.