8. Moulding and casting¶
For our group assignment this week, we all tested multiple materials to better understand the working time, properties and Group Assignment - Moulding and casting
Design¶
I wanted to create a small trinket based on my current most-played game, Helldivers 2. So I thought he logo would make a perfect fridge magnet or keychain.
Once again i’m fusion, so I started a sketch and outlined the side stripes
Here is a close up, I will later make small adjustments as I go to adjust for the milling drill-bit size by spacing things out more
To make things perfectly symmetrical, I only drew up one half of the design
We just need to turn the center line into a construction line to prepare for the mirror tool.
Here is our mirrored design
I also drew a rough side view, so i can cut the extruded skull
let us extrude the skull
I used a surface extrude here
At this point I decided it would look better as a keychain
Here is the final design
Milling¶
We were paired up to mill our designs, so we first put our designs on tinkercad
We loaded up our design on SRP Player, and we rotated it. We also did some adjustments to center the origin point.
We selected the following settings that matched our designs best
Next we created the tool path
after that “Preview Cutting” to get an idea of how it would look
This was the older design before adjustment, just to show how having gaps that are too small would cause issues
Much better now
We will also define two areas for the roughing and details
This let’s us avoid cutting the middle, saving on some milling time
We will wrap things up, and start out milling
Molding¶
After the machine was done, we got this result
Here is the positive mold after some initial cleaning, but the gaps and edges need a better clean
A quick wash and clean, and things are looking much better now
To estimate the silicon needed, we will weigh in the water.
My mold will need an estimated ~27 grams, so we will mix 30 grams of silicon
15 grams of base
15 grams of hardner
A good mix for 1 minute in the first container, and another minute back in the other container
Pouring in the positive mold
Final Resin Cast¶
Sadly something went wrong and the silicon was still a bit sticky. However I proceeded on with the resin.
This is the resin I used.
I mesured 10g Resin with 6g of Hardner (5:3 ratio as per the instructions), and mixed for 3 minutes. I then mixed in white acrylic paint to create the top part of the mold, and let it cure for 2 hours.
Then I mixed in black acrylic paint in a new batch of resin, and let the whole cast cure for 72 hours.
Here is the final result! Some minor blemishes were caused by the silicon not fully curing but it overall looks good. I particularly like going with the dual colors.
