UW HCDE 598 — Digital Fabrication Assignment 6: Molding and Casting — TriangLego

José Lara
May 27, 2019 · 5 min read

TL;DR: Milled something, created a mold of said something, casted copies of the something using the mold.

Lego pieces are amazing — unfortunately, there are no individual triangular pieces with three connectors, so it might be interesting to come up with an interpretation of what said piece would be like, to then mill it out of wax, and create plaster copies of it.

I started working on potential ways to create a triangular piece, so spent quite a bit of time on exploring the sizing starting with a regular 2x2 piece.

Image for post
Image for post

OnShape sketch for a 2x2 lego brick

Image for post
Image for post

Extruded sketch for a 2x2 lego brick

Image for post
Image for post

Trying to play with a triangle shape

Image for post
Image for post

Maybe I need to chop the triangle with a hexagon to make it a truncated hexagon

Image for post
Image for post

Experimenting with the connector placement

After struggling a bit with the possible ways to make this fit an actual lego set, I decided to explore the internet to see other approaches (I realized there would be zero ROI if I spent any longer working on my own implementation).

There was a great model that might probably not fit a Lego set, but aligned nicely to the ideas I was exploring and would be perfect for this assignment in SketchUp’s 3D Warehouse

Image for post
Image for post

After stealing downloading the SketchUp file, I converted to STL, and imported into Fusion 360.

Image for post
Image for post

STL for the triangular lego imported into Fusion 360

I started to play around with adding a stock directly in Fusion 360 that would represent the machinable wax

Image for post
Image for post

Model showing the lego inside to the machinable wax stock

I started simulating the process of milling the stock to get the part

Image for post
Image for post

Model showing the lego inside to the machinable wax stock

https://malvenko.github.io/HCDE598SP19/A6-assets/A6_SIM.mp4

With the toolpaths ready, I exported to GCode

Image for post
Image for post

I then realized that the stock was unnecessarily huge, so I’d deal with it directly on Bantam Tools. I adjusted the stock to be slightly larger than the Lego object.

Image for post
Image for post
Image for post
Image for post

WAX TIME!

https://giphy.com/gifs/art-week-notyouraverage-j9ayvgTlphafe

At this point several things happened:

  1. I had to get machinable wax at the CoMotiuon space at UW.
  2. The machinable wax we used for the class did not fit the Othermill
  3. Nadya set up office hours to use a larger milling machine (YASSS)

In the time it took to mill other students’ projects, I had time to tweak the STL piece and place it inside a brick of wax to make it easier to create the mold (just pour the silicone mix, and done!).

Image for post
Image for post

A different perspective

Image for post
Image for post

Setting up the mill after gluing the wax to the wooden base

Image for post
Image for post

Checking the paths one last time before pressing go…

Image for post
Image for post

Milling underway!

https://malvenko.github.io/HCDE598SP19/A6-assets/A6_MILL.mp4

Post-milling result

Image for post
Image for post

Prepping up the OMOO to create a mold out of the milled wax

Image for post
Image for post

Pouring the OMOO on the mold nice and slow

https://malvenko.github.io/HCDE598SP19/A6-assets/A6_POUR.mp4

After the pour

Image for post
Image for post

Six hours (and a bit) later…

Image for post
Image for post

Later, I poured in some plaster of Paris into the mold

Image for post
Image for post

The first batch of pieces after being removed from the mold. They need to rest for 24 hours to cure properly.

Image for post
Image for post

Four pieces curing for 24 hours!

Image for post
Image for post

The final product!

Image for post
Image for post

Learnings/takeaways

  • Although milling is faster than 3D printing, it is quite consuming to deal with multiple file formats and programs.
  • 3D tools (eg. Fusion 360) have a terrible usability — even if large companies (*cough* AutoDesk *cough*) are behind them.
  • 3D tools have incoherent features that WILL change units when importing/resizing or simply looking at it the wrong way.
  • 3D tools seem to be so niche that large companies most likely have no incentive to make them better, which is unfortunate, because on the longer term, with the right usability and format compatibility they would develop a solid following that would be adopted by students first, then professionals, eventually becoming a de facto tool for building 3D experiences in a dystopian world where reality has been replaced with an interactive 3D simulation where humans compete for money, resources, and love.
  • Plaster of Paris takes FOREVER to cure.

Source files for the mold and pieces

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch

Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore

Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store