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17. Project Development

What tasks have been completed?

  1. Frame has been modeled in Fusion 360.
  2. Frame parts have been procured/printed and assembled.
  3. Kevlar string drive system has been installed.
  4. Feet have been molded and attached.
  5. Stepper motor dual h-bridge boards have been made with the JLCPCB boards.
  6. Modular Things UI and coding have been completed for the stepper motors.

What tasks remain?

  1. Assemble and test the Raspberry Pi and touchscreen with a Raspberry Pi OS (64-bit) to run the Modular Things UI on Chromium.
  2. Design, mill, solder a DC motor control board.
  3. Design and print integrated toolholder for the DC motor spindle that will run on the gantry.
  4. Successfully mill and solder a Fab23 Dual H-Bridge board.
  5. CNC pockets for the molded feet in the wooden base of the machine.

What has worked?

  1. The assembled frame and Kevlar string drive system works when controlled by the stepper motor dual h-bridge control board with the Modular Things interface when connected to my SurfaceBook PC.
  2. The molded feet absorb vibration and keep the frame steady.

What hasn’t worked?

  1. Milling and soldering the Fab23 Dual H-Bridge board. I’ll get it to work, but it’s slow-going. I have the JLCPCB ones working, so it’s only a matter of time before I finish troubleshooting it, but it’s eating up a lot of time.
  2. The ESC control with the drone motor wasn’t able to be powered with the USB-PD hub, so I have to pivot and come up with a different solution.

What questions need to be resolved?

  1. The z-axis is a challenge currently. The biggest issue is space. I’m focused on designing a relatively small machine and the space requirements for a z-axis with the current design is hard to work out. I think I will need to delay that capability for another iteration.
  2. Replacing the drone motor with another option that will fit in the machine more easily and be powered by the USB-PD hub and potentially Modular Things interface.

What will happen when?

  1. Assemble the Raspberry Pi and touchscreen and test it out with Modular Things
  2. Design a DC motor control board for use with a DAGU-DG01D DC Motor. Theoretically the Dual H-Bridge can be modified to accomplish this task and still be powered with USB-PD. I will try reprogramming an existing board to see if it will work.
  3. Design and print an integrated holder for the DC motor on the gantry axis.
  4. Finish soldering the Dual H-Bridge board to be used on the machine.
  5. CNC pockets for the molded feet in the wooden base of the machine.

What have you learned?

  1. While it’s good to do research for answers, it’s also necessary to just try things after a reasonable amount of research/analysis and see what happens. After that, do more research and try again.
  2. My repeated failures soldering the milled Fab23 stepper motor dual h-bridge board are teaching me a lot about future board design for hand soldering. Essentially, have greater clearance around the XIAO pads and the traces going underneath the board, so it’s more fault-tolerant of slightly errant solder.
  3. I’ve also learned there is a difference between designing for digital fabrication with hand fabrication and designing for manufacturing. See above.
  4. Using a new interface like Modular Things is exciting, but it also means there isn’t a lot of documentation out there to work from, so it’s best to be patient and expect a slow go of it at first.