So this week I gave mold and casting a go for the first time! Figured it would be a good idea to practice molding before I do any bigger projects like the stave heads for my Mystogan Fairy Tail cosplay since those will be really big and everyone says it's a good idea to start small and work your way up to bigger projects.
For my first mold I did a simple Subaru key chain that I 3D printed.
Step one was to print out the key chain on my AnyCubic I3 Mega 3D printer:
Here is the key chain printed out finished on the print bed:
After that I hot glued the print to some foam core:
Then I boxed up the rest of the project with foam core walls and sealed up the seems with hot glue to make the mold box and got all my supplies ready. Mold max 30 silicone, mixing sticks, mold release, and a scale that can read grams:
Now for some math. I measured out about how much part A silicone I needed and then from that weight in grams I calculated the 100:10 ratio to mix in the part B or Part A value divided by 10= part B value.
Now that my silicone is mixed I had 45min of work time before it starts to set. I then did a air pour (since I don't have a fancy vacuum chamber yet to suck all the air bubbles out). This is to fill up the mold and also allow the air bubbles to pop out of the liquid rubber during the long pour. Now that the silicone is poured into my mold box I had to wait 24 hours for it to cure 100%.
After 24hrs of curing I freed the master, that ended up breaking since a ton of silicone leached under the print and I tried too hard to just pull it out rather than cut it free. But it was a 20min 3D print so no losses here. So once I cleaned up the edges of the mold and freed the rest of my master it was ready to pour resin:
Since the resin wasn't free I first filled the mold with water and measured the weight of that in grams so I could mix up the exact amount I needed. Before I poured, I made sure to spray some of my mold release into the mold since I didn't want anything getting stuck. After that I mixed up the 1:1 ratio by volume resin and poured it into my mold. I only had 3 min of work time (after 3 min it will go from a thin runny liquid to a gummy liquid as it has started to cure) and then 10 min before it was 100% cured and ready to take out so 13 min total. It is also really cool this resin starts out clear but then cures to white:
Finally I took my cured cast out of the mold . I just need to clean it up and will have a finished resin cast.
After some sanding to level off the back where the resin was poured in and some rotary tool work to clean everything else up I have a finished resin cast.
This was a really fun project and I enjoyed challenging my self to try out some new skills. For the next mold/ cast project I will try and do a more complex object, have it more finished before molding (rather than fresh off the printer, maybe some XTC-3D to smooth it out), and also try to tackle a 2 part mold rather than a dump 1 part mold.
Ohhh also I should have a stave project update this weekend! :D