Week 13 Assignments - Moulding and Casting

Cast Epoxy Resin Pendant with Encased 4-Leaf Clover

Group Assignment

The group assignment for this week was to:

Review the safety data sheets for each of your molding and casting materials
Make and compare test casts with each of them
Compare printing vs milling molds

Outcomes

Link to Group Site

The group assignment page for this week is on the 2025 Charlotte Super Fab Lab group site for Week 13 - Moulding and Casting.

Individual Assignment

The individual assignment for this week was to:

Design a mold around the process you’ll be using, produce it with a smooth surface finish that does not show the production process, and use it to cast parts.

Outcomes

Designing the Shapes for Molding

My partner and I are interested in the possibilities of casting for making different kinds of accessories, such as pendants. In particular, we wanted to explore using casting to encase things such as flowers or leaves as part of the design. I decided to create a basic pendant that would be large enough to encase a flattened clover.

I used Autodesk Fusion to create the pendant. The design considered that the pendant should have a basic clasp. It should also have enough area and be just deep enough to encase a flattened clover. The design consisted of the following basic steps:

Sketch an oval for the base and a clasp for the top
Extrude the overall sketch
Fillet the edges to round

Autodesk Fusion Model for Encasing Pendant

I also wanted to try creating a more complex shape for molding. I selected a sun shape.

I used Autodesk Fusion to create the sun shape. The design consisted of the following basic steps:

Select a foundational vector image for a sun shape.
Import the image into a Fusion sketch
Extrude the sketch
Add a connecting circle (sketch and extrude) to join the center and the rays

Creating the Shapes for Molding

In order to create the shapes for molding from the designs, I exported the Fusion designs as .stl files and used a Form 4 resin printer. The resolution of the resin prints would help to create a smooth surface that does not show the production process. I used the Preform slicer software to slice the models and create the prints.

Form 4 Resin Printing of Mold Shape

Once completed, the prints were available on the build plates of the Form printers. This is illustrated with the completed print for the sun shape.

The completed resin prints required some post-processing. For resin printing, the print needs to be washed in isopropyl alcohol to remove liquid resin. This is illustrated with the completed print for the pendant.

Pendant in Basket for Form Wash with Isopropyl Alcohol

Once washed, the parts need to be cured with ultraviolet light.

Pendant and Sun in Form Cure for Curing with Ultraviolet Light

Once cured, the basic parts are ready, but they have supports attached.

The supports needed to be removed as part of post-processing.

Pendant and Sun Prints With Supports Removed

While the parts are very smooth, there were a few places where supports had been attached that needed sanding to smoothen. This is illustated with the Sun print.

Creating the Molds

To create the molds, I followed the same basic process as we employed in the group work. For the molding, I used SmoothOn OOMOO 30.

I set up the parts for casting in a container for molding. This included the resin 3D printed pendant and sun. Since there was some space left in the container, I also included a small jade pendant that I thought would be interesting to test.

I applied some Ease Release 205 release agent to facilitate removing the pieces after the mold was set.

OOMOO 30 has 2 components - A and B - that need to be combined in equal parts and mixed for 3 to 4 minutes.

Mixing OOMOO 30 Components A and B

With the OOMOO 30 mixed, I poured the material for molding.

Pouring OOMOO 30 for Molding

The OOMOO 30 mold needs to cure for 6+ hours. Once set, I removed the material from the container and removed the individual parts to expose the molds.

I removed the parts and trimmed the edges of the molds to finish the process.

The mold for the sun part seemed to come out a bit ragged. Since the part was more complex, a variation on the process was tried. The OOMOO 30 was allowed to set a bit and the part was added in a different orientation.

Casting with the Molds

With the molds created, I began the process of casting. I prepared the molds with an initial coating of the Ease Release 205 release agent to facilitate removal after curing.

I tried 2 different casting materials. The first was a quick-setting urethane - SmoothOn Smooth Cast 305. The Smooth Cast 305 was mixed in 2 parts of equal volume and poured into the molds.

Unfortunately, the cardboard table cover was more uneven than expected. This resulted in some overflow in trying to completely fill the molds.

Smooth Cast 305 cures in about 30 minutes.

The uneven work surface caused the pendant cast to be too thin on one side, but the other partscame out well overall, with some need for post processing.

Urethane Cast Parts with Smooth Cast 305

With the initial practice on fast-curing Smooth Cast 305, for the second material I tried an epoxy cast. This used the SmoothOn EpoxaCast 690 material.

Epoxy Resin Casting with SmoothOn ExpoxaCast 690

The curing time for ExpoxaCast 690 is noted as 24 hours. In practice, to fully cure it took about 48 hours.

The cast parts all came out very nicely.

The extra jade pendant came out quite well, with good detail.

The main goal achieved, an epoxy cast pendant encasing a four-leaf clover.

Lucky Cast - Expoxy Resin Pendant with Encased 4-Leaf Clover

Design Files

Application design files for the project are: