Principles of Engineering — ReFilament

Designing a Funnel

We had previously used anything from a tiny PLA printed funnel to a paper funnel as a hopper, but the final system deserved something streamlined and effective.

Using Asana for Sprint Cycles: A Retrospective Journey

Our team utilized a sprint cycle methodology for completing tasks throughout the project. For those unfamiliar with the sprint cycle, it’s a theory of project management that goes a little bit like this:

Design choices — system housing

The system housing is the structure that hold our extrusion subsystem together. It must meet these requirements:

Python packages!

When I started building the ReFilament GUI, I started with the Python package Tkinter. I had already heard of Tkinter and from what I could tell, it was relatively easy to use. Building the homepage only took about 10 minutes, so it seemed like a viable option. Then I started to play with…

Digital caliper data collection

(Backdated: Nov. 10, 2016)

In order to measure the diameter of our filament, we decided to use digital calipers with a data output port.

NTC thermistor bridge

(Backdate: Dec. 1, 2016)

Today I built the thermistor-based temperature measurement bridge we’ll use for extruder barrel thermal control system. I specced a kind of glass-bead thermistor last week, one of the very few on Digikey that can get up above 250 degrees…

Switch to Thermistors

(Backdated: Nov 29, 2016)

Today I finally bailed on thermocouples. I couldn’t for the life of me figure out a good way to measure the tiny voltage they produce, even with an instrumentation amp with buffered inputs and a high gain stage. In light of that, I…

Bubble Adjustments

(Backdated: Oct. 28, 2016)

Our first Sprint Review was today, and we got some great feedback from our reviewers. For instance, we were advised that air bubbles can be eliminated using vibration or vacuuming. Both of those will be difficult to implement, but either one…