This week for Molding and casting .Molding and casting is a technique that uses different sets of materials to reproduce its molds for later replication. Goal of this week is designing a 3D mold, machine it and then cast it.
It starts from a design.
I used Rhino 3D For designing the mold ,I decided to design a Space Invader structure
First I draw 2D structure of space invader and then I enclosed it within a rectangle for creating the mold.
You must extrude the exterior sides as shown in the image below.
Then 3D model exported into STL format
Download STL file from here
Preparing the materials for making the form
Usually reproduced onto:
I decided to reproduced mold onto machinable wax with the Modela
Making the mold
Macine: roland mdx-20 (modela )
First i set the origin of the modela and noted it, because i am going to remove the material using two mills, first using a rough mill and then a ball mill ,so use same origin for both mill
Exported STL file open with fab module then choose "from format mesh(stl)" and "to process roland modela (rml)" here make sure to select the appropriate end tool, in my case I'm using an 1/8 mm end mill. Then i
configure the fab module parameters as shown in the image.
The path for the rough job should look like this:
Do not remove the wax block when completing first job .The first job is called rough which just sculpt the mold , when this is finished 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 with "1/8 mm, wax, finish", remove the wax block . Now mold is ready.
Next proceed with the casting.
Casting
For the casting I used Silicone Rubber(SORTA Clear 37) . It is a Water white translucent silicone rubbers which cure at room temperature with negligible shrinkage and feature high tensile and tear strength. The product is divided in two chemicals (SORTA Clear Part A and Part B ) that you have to mix in equal proportions
Measuring the volume of the form to estimate quantities required:
To calculate the exact quantity of material you gonna need, fill your mold with water, pour the water from the mold to the container you gonna use for the mixing . I used a transparent plastic glass
Next, pour the water into a cup and mark the top level then take away the water and fill the half of mark on the cup with the "A compound". Next step is take a new cup and fill the half of mark on the cup with the "B compound" and Red color color is mixed on to B compound. I use read color to mix on B compound. Finally mix the two compounds
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 6 hours
I checked after 6 hours and the silicone was cured
