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Molded Tesseract

A tesseract i.e. a 4D cube. Designed in Fusion 360 and molded in silicone

Molded Tesseract

For my week 8 assignment for How to Make Almost Anything (HTMAA) (6.9020), I decided to mold a tesseract out of silicon. Specifically I wanted to explore multi-part molds and this would require six parts – one for each of cube's faces.

Inspiration

During class, Prof. Neil Gershenfeld showed us a previous student who molded a hypercube. However this wasn't the first time I had seen this mold. In The Deep, one of MIT's makerspaces there is a 3D printed version of this mold. I used to run a silicion mold training every week there, and it was the model people were most interested in especially the squishy version which works as a great stress toy. Unfortunally, the 3D printed mold is netoriously hard to get a good cube out of so I decided to try make my own hypercube I could use for my trainings.

The Plan

The whole process consisted of:

  1. CADing the hypercube in Fusion 360
  2. Generating the negative of the hypercube
  3. Cutting the negative out of a block of wax on a router
  4. Molding the cube with silicion

Designing the Tesseract

To begin I designed the two cubes in Fusion being careful to use parameters for the sizes and thickness to make it easy to change in the future.

Cube inside another cubeCube inside another cube

Next I drew a line connecting the bottom corner to a top corner and created a pipe with a rectangular cross section.

Cube with an armCube with an arm

Then I circulated patterned and mirrored with arm to make 8 of them in total and get the finished cube

Finished cubeFinished cube

Of course, to mold the cube I actually need the negative of the space being taken up by my hypercube. I needed 6 parts – one for each face. I created a cube that was 10mm larger in width than mine and placed my hypercube inside. Then I used the Combine feature in Fusion to cut out my Hypercube from the block.

Cube with hypercube cut outCube with hypercube cut out

Then I created 4 planes each at a 45 degree angle cutting through the block to divide the block into 6 different pieces

Cube with 4 planesCube with 4 planes

Which gave me the piece I needed to mold

Negative of cube to moldNegative of cube to mold

CAMing and Cutting

I was given a 1.5"x3"x7" block of wax to cut my negative out of. I used the Shopbot CNC router which first required for me to create a setup file in Fusion 360.

I created a new Fusion file where I made block of wax. Then I inserted my hypercube negative and cut it out of the block.

Wax with cube cutoutWax with cube cutout

Then I switched to the manufacturing view and created a setup file. I first used an adaptive clearing and then a flat facing before switching to the contour finishing operation.

Adaptive clearing operationAdaptive clearing operation

Then I cut the block on the CNC router

Wax block after being cut by RouterWax block after being cut by Router

Molding the block

Since this was a 6-part mold I was pretty worried about getting it all done in time. Oomoo has a cure time of around 2 hours and my block only let's me mold 2 at a go so it would of taken a minimum of 6 hours just to make the mold to cast the cube in. Instead I went over to The Deep which had Mold Star which has a cure time of only 30 minute.

Firsly to figure out the volume of material I needed for my mold I placed some Cous Cous into the block.

Using CousCous to measure volume of wax moldUsing CousCous to measure volume of wax mold

Then I got my Part A and Part B of MoldStar and mixed them together. Unfortunally, Mold Star has a pot time of 6 minutes so I wasn't able to take any photos! After 30 minutes, I took out the mold and it was a success.

Two molded cube sidesTwo molded cube sides

I repeated this process 2 more times to get my 6 pieces

Two molded cube sidesTwo molded cube sides

Casting the cube

With my 6 pieces I could now, finally, mold my hypercube. I first applied mold release to all my pieces and then used elastic bands to form a cube shape.

Assembled molded cubeAssembled molded cube

Then I got Part A and Part B of Dragon Skin, another Silicion, and mixed these together with some blue dye and glitter for effect. I then degassed this mixture in a vaccum chamber.

Casting material beside cubeCasting material beside cube

Finally, I poured this mixture into my mold. After 24 hours I was able to take out my cube and it was a success!

Finished cubeFinished cube