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1. Final Project Proposal
2. Principles and Practices
3. Computer-Aided Design
4. Computer-Controlled Cutting
5. Electronics Production
6. 3D Scanning and Printing
7. Electronics Design
8. Computer Controlled Machining
9. Embedded Programming
10. Molding and Casting
11. Input Devices
12. Composites
13. Output Devices
14. Mechanical Design, Machine Design
15. Networking and Communications
16. Interface and application programming
17. Applications and Implications
18. Invention, Intellectual property and Income
19. Project Development

This week assignment is to design a 3D mold, machine it, and cast parts from it.

Designing the mold:

For designing the mold I used Rhino 3D, I decided to create an Space Invader then make the mold with the Modela and machinable was and finally cast it using RTV silicone. For my design file i started with 2D shape and then I enclosed it within a rectangle for creating the mold you must extrude the exterior sides as shown in the image below.



You can download the design files here

Machining with the Modela:

The 3D model must be exported into STL format. Then open the Fab modules and choose "from format mesh(stl)" and "to process roland modela (rml)" here make sure to select the appropriate end tool, I'm using an 1/8 mm end mill.



Load your image and configure the modela parameters as shown in the image. The first job is called rough wich just sculpt the mold when this is finished do not remove the wax block, change the tool option within the modules and choose 1/8 mm, wax, finish. and then send the the job again.



The path for the finish job should look like this:





When the job is finished remove the wax block and your mold is ready. Next proceed with the casting.

Casting:

For the casting I used RTV silicone wich is some kind of silicone rubber made of two components wich are combined at 2%.



The first step is to fill the mold with water so we can get the volume of silicone we need for casting the part. Next, pour the water into a cup and mark the top level then take away the water and fill the cup with the A compound.



The final step is to mix the compound A with the catalyst, for this use an electronic scale and get the weight of the cup with the A compound, then calculate the 2% of this weight, this is the amount of extra weight to add of catalyst, be carefull and add only what you need no more no less, otherwise it won't cure. Finally mix the two compounds for about 1 minute, don't mix in circles try to mix it with straight lines back and forth.



After a minute pour the silicone mix into the mold and when it's done let it rest. It's supposed to let it rest for about a day, but I checked after 4 hours and the silicone was already cured, it might be because of the heat conditions of the lab.