III. Fabrication and Assembly

Cutting Platform and mechanism

• This was the first sub-assembly we put together.
  • The platform, links, supports, and quarter-turn wheel were all laser-cut
• The black piece of acrylic was put on the cutting platform so the bread would be elevated and easier to cut. 

  • The sides or "bread blockers" we glued down (using an acrylic solvent) to ensure proper positioning of the bread; also so the bread wouldn't move around. 

• The links were put together using shoulder screws and acrylic spacers.
  • We used lock nuts to ensure that the assembly would not become loosened as it rotated around. 
• We used bevel gears to transfer the motion and drive the cutting mechanism
  • A metal/acrylic epoxy to fasten the gears to the metal shafts

Figure 1: Cutting Platform (showing cutting wheel, elevation platform, and bread blockers)

Figure 2: Top view of Cutting Platform

Figure 3: 4-Bar Cutting linkage

Figure 4: Bevel Gears

Geneva Mechanism

• The driving wheel of our Geneva mechanism was constructed using an FDM 3D printer.  It was secured to the vertical shaft with 1/4" collars and 2-part epoxy. 
• The quarter-turn component of the Geneva mechanism was laser-cut from 3/8" clear acrylic and secured to the adjacent shaft in the same manner.

Figure 5: Top view of Geneva Mechanism

Figure 6: Front view of Geneva Mechanism

MXL Timing Belts and Pulleys

• MXL Timing belts were used to transmit motor rotation based on similar applications with desktop 3D printers. 
• Pulleys were affixed to Geneva driving wheel and vertical bevel gear shaft with set screws, allowing for vertical adjustment.
• Through calculations motor supplied sufficient torque to overcome system friction and inertia, yet belts were too narrow too allow for proper funciton.