The assignment for this week is design a 3D mold, machine it, and cast parts from it.
I wanted to design a badge for fabacademy, I started to design the mold with solidworks.I first created small box of size of my mold and cut the small portion to place the badge.Then created a small circle with a star at the center.Then I added texts.
This was my initial design, but I had to change it since when I added it to the fab module, the text were not recognized in the path.
So I removed the texts and updated the design and save it as .stl file.
I designed according to the availabe machinable wax's thickness, so I took that piece and attached doubled sided tape.
We used Roland MDX-20 for machining, so I collected drill bits for it, 1/8 round bit for rough milling and 1/16 round bit for finish.
Since we are milling on Roland , I placed the machinable wax on the bed.Then placed the 1/8 round bit for rough milling.Like in the PCB milling, we use fab module for controlling the machine.First select as per following image:
Then load .stl< select bit< make png < make path. Now set x,y,z axes.
Then make rml < send it < begin mill, thus starts the rough milling.
After finished it change the drill bit to 1/16 for finish,change the drill in fab module gui also.Then start the milling again.
Here is a picture of finished mould:
For this we are using Mold Max 60 which is high heat resistant silicone contains two compounds known as A and B, mixing with each other in a specific compostion creates the mold.
First, we need to know how much quanity of this compound is needed for our mold, for this I filled my mold with water and pour it to a glass and marked the level.
Then, after removed the water I poured the part A compound to the glass just above the marked level and take the weight on a weighing machine.
This for finding compound propotion. Then with 1:100 propotion I poured the part B compound into a small plate.
Now part A and B compounds are mixed together and stirred it for about 20 minutes.
Then I poured the mixed compound to the mould.For removing air bubbles I had to gently tap the wax mould for sometime.
After waiting around 24 hours the mould was set, using a tweezer I removed it from wax mould.
Smooth Cast 305 is a liquid plastic, with two compounds A and B.
The compounds A and B are mixed in a 1:1 proportion, for coloring a Urethene color system is used.After taking same amount of compounds A and B seperately, they are mixed with color (I used yellow and then black ).Then soaking for sometime I poured it to the silicone rubber mold.
After waiting about 30 minutes (its cure time), my badge is ready.
For this, first we need to melt the babbit blocks, this can be done by using a furnace.Cut the babbit block into small pieces using bandsaw and place it inside the furnace.Babbit's melting point is 223 °C,set the furnace to that temperature and wait for it to melt.
After sometime pour it to the silicone rubber mold and again wait for it to cure.
And here is the final result: