Edward Octavio Muñoz Sandoval                                                                                                                   Contact: edw_ard0@hotmail.com

Week 12 Assignment: Molding and Casting


         1.- Design a 3D mold, machine it, and cast parts from it


First I had to design my piece, I wanted to do the half King of a chess game.

I designed it in solid works being careful with apply a radius on sharp edges to avoid problems when taking out the piece of the mold.

I didnt does it in the cross because I didn´t like how it looked.

I had to do other piece with the dimensions of the wood to be machined, then apply a cavity with the form of the king, being careful of apply just the half.


Solid works have tools that make this steps very easy.


Then I machined the mold in the modela using the .stl extension of the design.

In the left picture is the rough machined and in the right picture the fine.


The next step was saturate the wood to avoid problems unmolding the piece, so I applied sealant and wait like 2 hours until clean the waste of the mold

Before molding the resin, I applied mold release wax.

I prepared my resin with red colorant and the catalyst, but before that, insert two tacks to be involved by the resin

I had to be careful with the tacks, because at the beginning they float up , but after 5 minutes they remain.

I didn't have problems unmolding the piece and I loved the result:

Silicon mold

In this second part is explained an alternative to this assignment, which is design a 3D countermold, cast a silicon mold and cast parts from it.


The countermold was done in the software Aspire with the process explained in week 14, with the "Transformers" image in black and withe.

The next images show the mold being machined in the router CNC:

The result was acceptable but with the problem that the wood in the bottom broke.

The solution to this problem was clay in the edge to contain the silicon in the mold, but before I had to aply mold release wax.

The materials to cast the silicon mold are silicon rubber, diluent and catalyst:

Mix around 20 parts of diluent with 80 parts of silicon rubber, at the beginning is hard to mix because is very tick, but become easier slowly

Then Mix quickly 80 catalyst drops per 100 grams of silicon rubber, don't wait to much to pour the mixture in the countermold.

I waited 6 hours until unmold the silicon, it was fine but I had to cut undesired edges.

When the silicon mold was ready I cast a resin part from it, following the same process as I described previously in this assignment but without applying mold release wax.