12.5 Project Implementation

Electronics and Circuitry

The electronics system we constructed was largely built off of an Arduino Uno R3, with a few standard components: Motor Driver, Servo and Stepper Motor. These components were chosen for their specific use cases and availability. The stepper motor, connected directly with the motor driver, was set out of phase with the servo, so its function of rotating the clamp would be offset from the cutting blade. Originally, we had used a L298N motor driver, however, this particular model was ill equipped to be paired with a stepper motor, leading us to pair it with a dedicated stepper motor driver. 

Fabrication and Assembly

The fabrication of our final assembly was largely done through the laser cutting of wood/acrylic and 3D printing with PLA. Both of these production methods we had access to at TIW. Laser cutting was used for any flat structures, mainly plates and linkages, while 3D printing was used for any discreet, additive manufacturing components. Wood was the default material for the laser cut sections due to its ease of drilling in case more material had to be taken out. Acrylic can snap easily when under drilling loads, leading to its use case only for aesthetics or gears. Laser cutting also allowed for quick test cuts to ensure that all of the necessary press fits were tight, a crucial aspect for all of the mounting holes in the frame.

M3 and M4 bolts were used to assemble the linkages, acting as pivot joints, and were secured with lock nuts to prevent loosening during motion. Several heat set inserts were also used to ensure 3D prints did not require plastic threads.

The gears were laser cut from acrylic, selected for its dimensional stability and compatibility with the precision required for gear tooth profiles. Wood, being a composite material, is only truly strong in the direction of the fibers, so wood gears could snap and shear along the teeth surfaces, destroying the transmission. Accurate meshing necessitated the tight tolerances achievable via laser cutting. Additional components fabricated with this method included links 2 and 3 of the slider-crank mechanism and the can clamp/reverse drum brake.

All other components were manufactured via 3D printing due to their non-planar geometry, which could not be produced using 2D laser methods. These 3D printed parts included the bottom plate, rod tightening clips, can clap the connecting rods interfacing between the slider and rack (refer to Figure 2), link 3 of the four-bar mechanism, and the actuation arm blade. Link 2 of the four-bar mechanism, although featuring a planar geometry suitable for laser cutting, was also produced via this method due to its mechanical interface with the gear and integrated blade arm. All components mentioned above were printed using Bambu Lab printers, which offered the required resolution and material compatibility.

The final assembly was rather simple with all the consistency we maintained for connections. However, a few additions had to be made for cutting effectiveness. As the blade cut into the cans, there would often be too much friction between the blade tip and aluminum, causing the blade to pull the can further out of the clamp. To counteract this, we glued sandpaper onto the clamp sides, massively increasing the friction of the clamp onto the cans outer surface.