Assignments
Design a 3D mold, machine it and cast parts from it
CAD work
For this week i wanted to design a small 3d bottle that i could mold and cast
A bottle is not a complex thing to draw in 3D and i decided to design it in Fusion 360
I started off by drawing some lines in the sketch mode
After i had finished my sketch i could revolve it
This is how the final version of the bottle looked like and the rendered version
My next step was to export my 3D design and create a mold in another 3d program
I decided to make the mold in Tinkercad
It´s a beginners 3D program that i have used before and documented on before in Fab Academy
I made walls for the mold, and pins that would fit into each other
I inserted a paraboloid into the bottle to pour liquid into the two molds that would be pressed together
Vcarve Pro and the Shopbot
Now my next step was to open my finished 3d file in Vcarve Pro
I was going to cut my part in basic purple wax
I measured the wax piece and determined the sizes in Vcarve Pro
The program gives you a good idea on how the cut will look like, if it will succeed
The end mill i used for this job was a 1/8 inch ball nose
My next step was to create a rough machining toolpath for the wax
I changed the default settings of the stepover percentage to 9% and the feed rate to 100
After i was finished with the rough machining i could jump to the finish toolpath
I set the feed rate to 100 again but changed the stepover percentage to 4%
Now i was ready to prepare the cut
I glued the wax to a wooden plate and screwed it on the plate on the shopbot
My next step was to cut out the part
Making the mold
My next step was to make a liquid rubber mold for my bottle
I used a mold kit from Smooth-On
It includes a dry rubber mold compound and urethane mold compound
I followed the instructions on the backside of the packaging for the mixing
I put equal amounts of the dry rubber and the urethane mold into two different cups
Then i combined the molds and mixed the liquid rubber thoroughly carefully
After the stirring and mixing i poured the liquid into the wax and let the mold dry for the next 24 hours
I was fairly happy with the results. The joints were succesful but i felt the mold was maybe to wet and greasy and it had some air bubbles in it
But it sticked nice together thanks to the joints and i wanted to try this mold
Casting
I wanted to start off by making a hydrostone cast
When i designed the mold i made sure to have a hole to pour materials in the mold
The joints on the mold were succesful so could stick the two molds together perfectly
I used clamps to stick them together for the pouring of the material
I used hydrostone powder from DryStone casting media
My next step was to mix the hydrostone powder with water
My instructor Frosti, told me that it was ideal to mix the water and powder together until it felt like yogurt
After a few minutes of mixing i poured my hydrostone cast into my mold
My first try was unsuccesful because i poured to fast into the mold
That resulted with the cast not getting through the hole
I gave it another go and my second try was succesful
Here´s what my hydrostone bottle looked like after taking it from the mold
