Team B: Jaws

Project Goal

Our primary goal for a can recycler was to create a machine that would be able to obtain a large compression ratio while also being fast. To be fast, we would have to work with multiple cans in no specific orientation. By avoiding the tedious time it would take to orient and process each individual can, we would be able to achieve our quick processing goal. After a little research, we decided that shredding the cans would be the most effective method to accomplish this. This method also allows us to shred cans of different shapes ans sizes

System Overview

Being that our system would be rather dangerous when complete, we focused on the user safety of the machine. We incorporated as many safety mechanisms that we could to prevent any possible injuries. One of the overarching ideas was to automate as much of the process as possible. The automation would reduce the amount of user input and allow the machine to handle itself. Once complete the entire shredding process was automatic. The user only loaded the cans and unloaded the shreds after the process was complete. When the lid was closed and the "Go" button pressed, the lid would lock shut, the teeth would activate and start moving, the safety door that would block the teeth would open, and the cans would shred. The system would detect when there were no cans left to be shred and close the safety door, stop the teeth and unlock the lid, ready for more.


Lid Lock
The lid locking mechanism is activated first to ensure that the user does not interact with the cans that are in the process of being shredded. To know that the lid was closed we employed a photo gate such that when closed, the lid would interrupt a beam, sending a signal to the system and allowing the process to begin.

Safety Baffle
To ensure that the user does not interact with the operational end of the device, the automated safety baffle separates the loading area and the shredding blades. When the process is started, the door opens once the blades are moving and allows the cans to fall into the teeth to be shredded.

Drive Train
The system was driven by an AC motor that had 1/3rd of a horse power. This was more than enough power to shred our thin cans and on more than one occasion forces us to make a few changes to our structural design. This mechanism would not always start the first time so we placed and encoder to watch and make sure that the shafts were turning when they should be.

User Interface
Since most of the machine is automated, the controls are very simple. There is a single "GO" button which starts the machine and in the event of an accident, and emergency stop button. When running, there are warning lights to signal the states of the machine.

Capacity Sensor
We added a small IR sensor to detect the presence of cans in the machine. When the sensor doesn't detect any more cans, it beings the shut-down process to allow the user to interact with the shreds and add more cans to the system.

Our system obtains its power from a borrowed computer power supply unit. It's brains come in the form of an Antel Xmega processor board. These electronics power the entire system aside from the drive train.

Shredding Teeth
The teeth themselves are laser cut from a sheet of 1/2" acrylic that was designed to stop hockey pucks at an ice rink. Design and spacing of the teeth was determined through trial and error to allow for maximum shredding without breaking the teeth or stopping the motor. This same material was used as the wall material to keep cans from leaving or the user interacting with them.


The final operation was fairly good in terms of the speed and various size. The compression ratio was however a disappointment as we were unable to attain the specified 3:1 ratio. This issue is primarily due to the strength of our acrylic teeth. If we were able to use a stronger material, we would have been able to shred them more efficiently without the danger of having teeth crack and break.

Flowchart of States

Video of System

Team Members
Ben Matzke:
   Shredder design and Fabrication
David Alberts:
   Structural design and Assembly
Kevin Kassing:
   Electronics Programming and Integration
Nam-Phuong Cong-Huyen:
   Electronics Assembly and Integration

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