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

For this assignment I sought  the possibility to machine an organic geometry mold, despite the geometry I made is very simple I learned a lot about how to machine this kind of surfaces and how to use them as a mold.

As industrial designer I already have some experience with silicon molds, because of that I wanted to try a different technique so I decided to make a wood mold using the 3 axis machining process of the CNC router.

The first step was to model a surface in Rhino with the desired form, with that surface I started the design of the mold, I used  tools such as extrude, join, booleans and some others to get the mold done. It's important to mention that the edges are slightly angled to permit an easy unmolding. To machine this mold first I exported the model in a .stl format,  which is admitted by the software  Aspire to perform the surface machining. After importing the model, I programed the machining, first is the rough process, in which I used a .25 inch cutter. The second step was programming the finishing, for this  I used a .25 inch ball cutter. Both programs were ran separately to avoid some problems detected on prior practices.

The software used (Aspire) is very intuitive, it has enough tools to keep the entire process under control.

You can download the files HERE

With the G code ready I started the machining process with the router. Because the size of my mold was considerable small it was very fast to machining, it took around 12 minutes.

For the casting process I gave a better finishing to the mold, so I have sanded it a little bit, then I used some wax as a release agent I have to mention that this is a important step, otherwise the casting process would fail because the impossibility of taking off the poured material. Once I finished with the wax I used some isophtalic resin, after catalyzing it  I poured it into the mold.

Some marks made by the wood texture were copied by the resin however with some wood putty is possible to erase them from the mold and from future pieces.