Design Specifications

Overall Workflow

Demo Video

Overview of Machine

Mechanical Parts

Frame

  • Ender-3 3D printer’s frame

XYZ-axes motors

  • NEMA-17 motors X3 (Original motors of Ender-3 3D printer)

Stamp Assembly

  • 6-wheeled V-slot gantry
  • 3D printed stamp assembly platform
    • Designed to maximize the working area of the stamp over the lower platform
  • Tape unwinder and rewinder (Extruder 2 and Extruder 1): NEMA-17 motors X2
    • Holding torques of both extruders keep the upper tape taut throughout the exfoliation process
  • 3D printed stamp:
    • Flexible stamping base with soft silicone
      • Flexible 3D printed structure inspired by the flexible support printed during usual 3D printing processes
    • Springs above the flexible base
    • Designed to exert sufficient pressure
  • 3D printed tape holder
  • Tape for exfoliation

Lower Platform Assembly

  • Graphite Holder:
    • 3D printed slanted holder with grove
    • Clean glass slides so that the graphite samples will not be contaminated when placed on the glass slides
  • Graphite Deposition:
    • 3D printed slanted holder with grove
    • Silicon wafer as the substrate
      • At first, PDMS was used. However, very thin layers of graphene are not clearly visible on PDMS under an optical microscope. 
  • Exfoliation Assembly:
    • 3D printed slanted holder with grove
    • 3D printed tape holder
    • Tape rewinder (Extruder 0): NEMA-17 motors
      • Only a single motor is used because we realized that not keeping the lower tape taut actually helps exfoliation. 
    • Tape for exfoliation

Tape for exfoliation

  • PET tape
    • Leaves least residue on silicon wafers
      • Random tape from some shop and Scotch tape leaves too much residue
    • Best exfoliation performance
      • Exfoliation stops after a few repetitions for Magic tape
    • Not too sticky for Z-axis movement
      • The random tape is too sticky and the bottom tape gets pulled up too uncontrollably

Hardware and Software

Wiring and Firmware

We used Arduino with Marlin firmware to control and automate the machine.

Wiring Guide:

In order to set up microstepping, we connected jumpers to ensure the respective ports (MS1, MS2, MS3) are HIGH. If not, they are LOW. 

The microsteps mean how much they will move for every movement (if your step angle is 1.8 degrees a sixteenth step is 1.8/16 degrees movement) helps if you want precision.

 

Regarding wiring for motors, we use ender 3 where we have the x, y, and z axis for movement.

 

On the Ramps 1.4 Board, you will see X Y, and Z. They are basically where you should put your drivers and motor wire connections for motors that dictate those movements respectively.

 

To connect the driver for the X-axis motor, go to the X-axis and notice that there are pin slots that seem to fit the A4988 Stepper motor driver. Please connect the Enable pin on the Stepper motor driver to the enable slot on the Ramps 1.4.

 

Next, connect the stepper motors to the ramps board, using the stepper motor connecting wire.

On the Ramps 1.4, look for the 1A 1B 2A 2B pins. We connected it to the stepper motor using those pins.

 

We repeated these steps for your X Y Z and extruder motors. We also added a 3rd Extruder motor.

 

G-code

G1, G28, G92, G4 were used.

 

Python GUI