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Final Project

Original Idea (Abandoned)

Here is the preliminary sketch of my final project

Final Project Sketch

It’s a portable air conditioner for a jog stroller using ice water as the coolant. The occupant of the stroller will lay their back on a heat exchanger that has cool, but not cold, water circulating through it. Ideally the water running through the heat exchange will be a ‘comfortable’ 60 F.

The inspiration for this project comes from my time as a stay-at-home dad and all the time my fourth child spent in our BOB stroller being carted around to events for their older siblings and on walks. It was a great stroller except in the heat of the summer in Charlotte when it became uncomfortably warm in the stroller while on a walk/jog or sidelines of a siblings’ sporting event.

I envision the heat exchanger laying between the child’s back and the seat back of the stroller with water circulating through some tubing that is encased in a pad. We’ll see how it develops.

In the week 4 recitation on projects Neil mentioned a proximity sensor that allow for sensing through material using electric fields, so it doesn’t need clear sight. I will investigate.

Smooth-On Sorta-Clear cast silicone rubber material for the casting.

Here are some parts that I think might be useful:

  1. Water Pump to pump the water around the system.

  2. Liquid Level Sensorto be sure that the level between the reservoirs doesn’t get too imbalanced

  3. Temperature Sensor to allow for auto adjustments of the mix rate of the cold resovoir and the recirculated water.

Post Machine Week Update

New Project (Current)

  1. As a mechanical engineer, I really enjoyed working on our “fab Buffer” group project for machine week and have decided to change my final project to improving our machine. Part of the motivation for changing to this project is that I’d like to use it as a springboard to develop a high school engineering curriculum on machine design.

  2. Here are some of my goals for the improved machine:

    1. Simplify the assembly of the design by improving the fit of some basic components with some spring loading of the wheels on the extrusion.
    2. Accurately model the machine in Fusion 360 with a mechanical design study.
    3. Use off the shelf components for the base design.
    4. Make custom electronic board components to match with the Crealty stepper motors
    5. Add electronic z-axis control (stretch) using LIDAR to move the bed to the correct height.
    6. Integrate gyroscope sensor to smooth our the CoreXY motion with a feedback look for acceleration and deceleration.
    7. Use solely USB-C power for the machine.
    8. Design for ease of assembly.
    9. Have an external control box that will house the microcontroller and operational buttons.
    10. Contained in external box for safety.

Electronics Design and Production

  1. Since I’m fairly comfortable with mechanical parts of the existing machine. I’m going to focus on the electronics first.

    1. To start, I’m going to make and understand the Xiao_RP2040 Dual H-Bridge board from the Instructor Boot camp 2023 to see if I can understand how it works, so I can then adapt it to my project.

    2. I ran into some issues with downloading the existing board to be milled. We don’t use Mods in our lab, so I needed the BRD file to use in Eagle or KiCad. When I clicked on the link the file didn’t download the BRD or SCH files like I’m used to. Here is what came up instead.

      1. This XML file does not appear to have any style information associated with it. The document tree is shown below.

      2. BRDDownloaderror

        1. I went back and tried to right-click on the file to see if the “Save File As” option appeared and no luck. Here is what I got. “Save link as” which seemed like bookmarking the site which was still no use.

      3. RightclickBRD

    3. I did some internet searching for importing XML files into Eagle or KiCAD and came up empty, so I tired to copy the text in to a Notepad file and change the extension from “.TXT” to “.BRD” and no luck. I kept getting import errors.

    4. At this point it seemed like I would have to recreate the board in KiCad using the PNG file as a template, but I was reluctant to do all that work as from a process perspective I didn’t feel I had exhausted all my options. However, the clock is ticking. It presented me with one of the typical Fab dilemmas use the brute force approach and recreate the wheel since our tools are similar but not the same to just get it done or keep searching for a simpler solution. When I showed other people the issue it was something they had not encountered, so I was really stuck.

    5. I decided to wait until the next morning ask in Global Open time to see what I might be doing wrong. When I brought it up in Global Open Time, Adrian and Rico were initially confused, so I was able to share my screen on the Zoom call. Adrian navigated to the same page and right-clicked and got same spot, but his was in Spanish, he indicated that all I need to do was click on the fourth item down, and it would work. I tired it and it did. Easily solved and frustrating at the same time. Typically, in Chrome right-clicking on a file link bring up the option to “Save file as” and it’s no issue, but “Save link as” typically (until this instance) only allows you to save a link.

    6. As frustrating as this was I’m glad I didn’t give up and recreate the file because it’s happened before when I’ve been browsing files on the Fab site to mill as a starting point. By realizing this quirk in the system, I just widened my options for starting points for designs. Worth the effort.

    7. Some time has passed and I’m coming back to this project. I’m looking at the motor driver board for this project and it seems like there is an updated motor driver for Clank that may work. I found the Building Clank site and opened the Fusion 360 file and took a look. The board was part of Modular Things. When I went to the site and looked and found it to be stepper-hbridge-xiao

    8. I’m reviewing the motor drivers I was going to use for this project to see if any updates have been made to the Xiao_RP2040 Dual H-Bridge board I was planning to use.

    9. It looks like updates were made during FAB23 Machine Workshop to the whole base design I started with, so I will start updating my design.

    10. The first item I’m going to concentrate on is the Xiao RP2040 HBridge Board2. I downloaded the file and took a look at it in KiCad 8. It seems pretty straightforward to mill.

    11. While it seemed straight forward to mill, I’m having issues getting the ground traces to mill on our OtherMill Pro and Bantam Desktop CNC. When I loaded the gerber files into the Bantam Software the milled file does not match the gerber. See the two screenshots below.

      1. Gerber
      2. Bantam

    12.

3D Modeling

  1. I will be using Fusion 360 to model the design for my final project. First I must move the file from our machine week group page to my personal account. I think the best way to do this is to download the model and the upload if to my Final Project folder in Fusion. The machine week model is in an account with Basic Access and cannot be downloaded, so I will remake the Fusion Model with the noted improvements. This will allow me to work on my Fusion360 skills.

  2. Issue-When copying and pasting the extrusion components in Fusion 360, the copied component and the original were linked and modified together. For example, when modifying the length of the extrusion it was copied from would change in sync.

  3. A little online search found the solution

3D Printing

  1. The

Laser Cutting

Coding

CNC

Molding and Casting