Week 13. Moulding and Casting¶
Group Assignment¶
This week, during our group assignment at Fab Lab Dilijan, our instructor Mkhitar Evoyan introduced and thoroughly explained the processes of molding and casting, covering their main principles, applications, and the materials used.
He demonstrated how molds are created using different methods, including milling and 3D printing, and explained the specifics of casting with various materials such as metal, plaster, plastic, and silicone.
After the theoretical part, we moved on to the practical work, where we were assisted by Areg Khalatyan. First, our teammate Hrach designed the part that would serve as our master model. More details about that process can be found on Hrach’s page.
Individual assignment¶
After the group assignment, I moved on to my individual work, where I tried to practically apply the knowledge gained during the group project.
At the initial stage, I was not only thinking about what kind of object to make, but also trying to connect it with the idea of my final project, so that the work would not be a separate experiment, but a continuation of the same concept. Following this logic, I decided to make a coin-shaped object, which can be viewed both as an independent piece and as a symbolic or functional part of my main project.
Design Part¶
I started with the main body of the coin. In FreeCAD, I drew a circle and used Pad to create volume. I chose the height so that it could later fit easily into the wax.
Then I added a slight taper to the sides (taper angle around -6°), so that the side surfaces would not be completely straight. This helps the part come out of the mold more easily.
After that, on the top surface I drew concentric circles again and used them to form the characteristic outer ring of the coin. I raised that section using the Pad tool, creating a defined border. At the same time, this also helped provide sufficient wall thickness, making the part stronger and visually more complete. A small taper angle was also applied to that Pad, so the edge section could separate from the mold more easily.
Then, in the central section, I drew the main curved line of the yin-yang symbol and raised that outline using the Pad tool, so that the symbol would stand out from the main surface. This made the symbol more expressive and visible, while the raised relief gives the finished part interesting light and shadow. I chose the height carefully so that the shape would be clear while the overall structure remained balanced.
Then I added a moon shape on one side and sun rays on the other side. These were also made with separate sketches and then raised from the surface using the Pad command to the necessary height. Taper angles were also applied to these Pads, so the side surfaces would be slightly angled and the part could be removed from the mold more easily.
Finally, I added small stars in the empty background areas so that the surface would not remain empty and the composition would feel balanced. I placed the stars in different positions to make the design more lively and dynamic. A small taper angle was also used on them, so that all decorative elements would follow the same structural logic.
After finishing the main coin design, I realized that the shape alone was not enough, because it had to be placed into a mold in order to be machined and cast later. For that reason, I designed a square outer frame around it.
I chose the square shape so that it would be symmetrical and visually match the circular coin design in the center. I left enough surrounding space so that the walls would be strong and would not be damaged during the working process.
I deepened the inner section, creating a cavity in which the coin design remained in the center. I intentionally rounded the corners, because sharp corners are difficult to machine with a milling tool, while rounded sections also make removal from the mold easier later. I also gave the walls a slight taper angle, so that separation from the mold would be easier.
After creating both the coin design and the outer mold structure, I needed to combine them into a single object. For this step, I used the Union (Fuse) tool in FreeCAD.
First, I selected both bodies (Body and Body001) from the model tree. Then I applied the Union operation, which merges multiple shapes into one solid object.
This step was important because:
- it ensured that the model would be treated as a single piece during machining
- it removed any separation between the coin and the surrounding frame
- it made the geometry cleaner and more suitable for exporting
Generating G-code (Mods Project)¶
After completing the 3D model, I moved on to the next important step — generating the G-code using the Mods Project platform.
At this stage, I used the mill raster 2.5D module, where I set the tool diameter to 3 mm, which is suitable for removing larger amounts of material during the initial milling process.
However, since my design included smaller and more detailed elements, I decided to change the milling tool afterward. I switched to a 0.75 mm tool, which allowed me to achieve finer details and improve the overall precision of the final result.
