Scribe Resin Casting Class
Resin Casting Class
While working as a student machine shop technician at Cal Poly, I often created different trainings for other shop technicians and students to learn more about different manufacturing methods. One example of these trainings was when I created a class to teach students about silicone and polyurethane casting using 3D printed molds.
For this class I designed a very basic scribe mold that showcases good mold design practices and that creates a functional polyurethane scribe. I chose to create a mold for a scribe because it not only provides a simple part for students to cast but also creates a tool we can use and stock in our shop. Additionally, due to its small size, the cost of the scribe is very low making it ideal for trainings.
Scribe Design
The scribe itself is a very simple design. It features a carbide scribe tip with a cast polyurethane plastic body around the tip. The polyurethane body has a hexagonal body that tapers off into a skinnier circular design.
The design was purposefully a very simple geometry to create a very simple mold design. This simplifies teaching resin casting mold design practices and makes it easier to understand the concepts.
A quick curing polyurethane plastic resin was used to cast these scribes because it allows the scribes to fully cure before the training ends. This allows students to take their cured scribes by the end of training versus waiting a full day for the scribe to cure.
Mold Design
The scribe mold features a sprue and tapered inlet to the mold. This allows for easy pouring of resin into the mold. Both the sprue and runner help guide the resin to the bottom of the mold. By filling the mold from the bottom as the resin fills the mold cavity, it will push air bubbles towards the top of the part. This prevents air bubbles from forming in the part. The vent is located at the top of the mold cavity to allow air bubbles and the resin to exit at the top of the mold cavity.
The mold also features an overflow ring around the mold cavity to capture any resin that may leak out during the curing process. It also has tabs to make separating the mold after the part has been cured easier. Additionally, there are screw holes to clamp the two mold halves together.
Resin Casting Class Curriculum
For the resin casting training itself, I designed the training to take 2 hours to teach 6 students about resin casting. The training provides students with a brief introduction to different mold types, the advantages of resin casting, good mold design practices, and a general overview on the resin casting process. The training takes around 30 minutes going over an introduction slideshow and then uses the remaining time to allow students to cast their own polyurethane scribes.
