I undertook this project in order to develop my understanding of mold making, plastic materials and to gauge the possibilities that 3D printing may play in limited run product production.

 

The design was developed and finalised using SolidWorks 3D modeling software and in turn this design was 3D printed on a desktop machine. Due to the small bed size of the machine - I had to split the model into 3 pieces - which were assembled later.

 

With the higher grade 3D printers it is capable to cast straight from the print - though; as I was using a desktop device; the low resolution meant that I had to prepare the print before it could be molded. I applied builders bog to all print surfaces and sanded them back smooth, this was repeated until the entire print was smooth to my satisfaction.

 

I felt that achieving the smooth internal bowl surface through sanding would be tough - so instead opted to cast the bowl shape using a balloon (I simply applied builders bog to a balloon which was inflated to the right size). When dry the balloon was popped and the cast trimmed and assembled to the existing print.

 

Firstly I attempted to mold the piece with plaster of paris. This was going to be hard and complicated due to the nature of the design - requiring 4 pieces to allow it to be removed. Seperation lines were built with clay and each piece of the mold was poured. Ultimatley the mould in plaster did not yield enough detail and was too fragile as well as heavy.

 

For the second molding attempt I used FLEXICAST 45 - a slow set Polyrethane Elastomer. This is a 2 part system and took around 24hrs to cure. Since this material was elastic to some degree meant that I only needed to make 2 mold pieces (a top and bottom). The print/plug was destroyed though as I was a bit rough on removal.

 

I cast this bowl in a High Grade Gypsum (like Plaster of paris but stronger and scratch resistant) and Rotothane - a 2 part quick setting Polyurethane.

 

The Rotothane was the most successful providing great detail,  quick set time (around 5 minutes) and minimal weight as it is hollow.