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Mold and Casting

Digital Fabrication Assignment 6

Mold and Casting Overview:

  • Synthesis / Define
  • Ideation / Develop
  • Test / Implementation / Deliver
  • Reflection

    • Synthesis / Define

    Design Prompt Criteria:
  • Criteria #1: Design and fabricate a mold in silicone.
  • Criteria #2: Use the mold to cast at least 4 identical parts (e..g in plaster).
  • Criteria #3: Design your master part in CAD first, then design your mold, then design a mold to cast your mold in.
  • Criteria #4: Fabricate your mold's molds either by CNC milling machinable wax or by 3D printing.

    • Ideation / Develop

    For this weeks project, I started off by considering making a mold with a functional purpose. For a father's day gift, I decided that a Sextant mold would entertain my father and he could use it as a business asset.


    After I tried making a Sextant model based on an Inspirational Sextant ,
    I decided to keep it simple so I downloaded a Sextant to act as the detailed model inside the Positive Mold. ( Sextant by IESSanchezCanton is licensed under the Creative Commons - Attribution license. )

    Test / Implementation / Deliver

    Initially I focused on learning the software to design my mold, utilizing Onshape for the Mold Base then Fusion 360 for the Sextant Model and for the assembly.
    This process enabled me to become much more familiar with Fusion 360. This allowed to become much more familiar within the different modes such as Manufacturing, adding new operations like manual tool changes, for milling.

    For example I learned how to convert the Stl models from Thingiverse using the Mesh to Bbodies function.

    Exploded view of an early prototype with restriction points and a sprue.

    Filler

    The original plan was to learn more about subtractive cutting with Fusion 360 and the CNC tooling system.

    Problem

    The plan was to cut the primary body of wax with a 1/8th" bit followed by a 1/32" bit to cut the intracies of the Sextant. However the projected cut time for the wax material was acround 6+ hours. I iterated by switching over to 3D printing for quicker and more reliable results.

    This was the right decision but It create it own set of issues One problem that I encountered with 3D Printing was that their was a kill point in the model's Gcode output causing the print to cut itself off at a certain point.
    The bug was due to a small setting in the original design of the Manufacturing tool mode.
    The bug, a manual tool change operation, was the reason why it failed two times. On the third print, the reel jammed causing a misprint. Fourth attempt resolved the issue.

    3D Printed a Positive Mold so that negative Mold could be produced with OOMOO 30

    The output crumbled when removed from the negative mold.

    Filler

    Repurposed 3D printer errors to make a double sided mold and tested its output.

    Solution

    Overall I was able to overcome my issues by troubleshooting the technology. I was able to leverage mistakes made early on to help me recover later on. For example, from the two part mold I learned that a square plaster platform improves the intergrity of the Sextant piece as more surface area is attached to a platform.
    With this takeaway in mind, I applied it to the smaller one sided mold which maintained its form when pulled out of the mold. This key insight enabled me to complete the assignment with out having to make a new mold with Oomoo 30.

    Explored the use of a single sided mold and a double sided to mold to see which design produced the best results.

    After testing each mold, I focused on using the single sided mold to cast the Sextants.

    Filler

    Final four plastered pieces fulfilling assignment requirements.

    Reflection

    This project was one of those projects that sharing information was crucial and improved peer bonding with one another.
    In hindsight, this project was a succesful balance of skill and challenge for me. By focusing on the outcome I was able to overcome obstacles in a timely manner.

    Attribution:

    Joshua, Angel, Dhwani Vekaria, Julie Do, Peter, Andrew, Nicole, Demarcus, helped each other out with best practices.

    Machine Settings:




    Source files

    Click the Items below to acces the Source Files
  • Sextant by IESSanchezCanton is licensed under the Creative Commons - Attribution license.
  • Bantam Tool Guide
  • Inspirational Sextant
  • OOMOO Overview
  • MIT Student Process
  • Onshape Base
  • Fusion 360
  • Gcode