Electronic Product Design Progress Report: Week 7

PCB Design: Version 3

Having tried multiple times to unsuccessfully solder the TSSOP version of the MCP23017 to the version 2 PCB, I decided that a redesign was needed for the PCB. This also gave me the opportunity to replace the original RGB LED to a 5mm neopixel in order to have access to more colors for the interface.

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Changing to the neopixel also lessened the amount of wires between the main PCB and the Feather Bluefruit. The board was retraced and sent to OSHPark for printing. It is estimated to arrive within the week.

3D Printer Purchase

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After using the 3D printer in Leslie eLab, I realized that purchasing one would be an excellent way to prototype without having the hassle of scheduling time and traveling downtown. Upon hearing how successful it was, while being affordable, I purchased an Ender 3.

Since this is a no-frills printer, I decided to add a couple of features to make life a little easier. Firstly, I added a better Bowden tube in the hopes that it will be more reliable than the stock one. Capricorn makes a tube that is not only better quality but works well with printing TPU and high temperature materials. I thought by adding this, it would make printing flexible materials much easier due to being more slippery than the stock tubing.

Due to a concern with thermal runaway, I upgraded the stock firmware to the unified firmware made by TH3D. This firmware also allowed me to add their auto bed leveling modification which reduces the hassle when starting a new print. So far, this kit has performed extremely well. However, I had to modify the amount of calibration points to compensate for the lousy stock bed; now it takes 15 readings instead of the stock 9.

After experimenting with printing NinjaFlex TPU, I realized that I will require one more add-on as the material was backing-up out of the Bowden tube during all of my test prints. I ordered a SeeMeCNC EzR Struder to replace the original extruder.

Next Steps

Next week, I will receive version 3 of the board. Upon soldering and testing, I will make a new 3D printed case using PLA and TPU. I have already been experimenting with phone clamps and may have found a solution to print that utilizes rubber bands as the spring mechanism that holds the phone in place. I am hoping to have the product out for testing within the next two weeks.