This tutorial will explain how to make molds of and cast relatively small 3d printed components. I am still learning, so feedback and questions are appreciated! I will update images as i go.
Step 1: Gather Materials
You will need:
- The object you wish to cast
- Resin, obviously. I used Smooth Cast 65D resin
- Silicone for molds, I used Mold Star 15 SLOW
- Scalpel or exacto for extracting the molds
- Cardboard or plastic for mold frames
- Plastilinia clay
- Gloves (non-latex)
- Mixing cups/sticks
Optionally you can also use a vacuum chamber
Step 2: Sand and Prep Your Parts!
This is the easy step. Depending on the quality of the parts you want, you can sand and prime the 3d printed components like regular plastic. Every little detail will be rendered in the mold, and therefore in the resin. I chose not to sand my components very hard, as i know that it will be easier to remove imperfections in the pours than the masters.
Step 3: Set Up for Mold-making
In order to make a part, you first need to make the mold. Using scrap cardboard and hot glue, i made a rectangular box to pour my silicone into. I then used clay to form supports for the parts, to form the "pour tubes" for molding.
Next, I mixed the silicone.This particular mixture is 1:1, so after carefully mixing each individual container i poured roughly the amount i thought I'd need into a cup and mixed it with a plastic stick. Be careful to only use containers, gloves (and please do wear gloves!) and stir sticks that do not contain any chemicals that will inhibit curing, as this leads to nasty and useless slimy molds.
Once the compound is mixed, it will be on it's way towards curing. If you are using a fast-curing type, work fast!
Step 4: Make the Mold
Now, it's time to pour! This step is relatively simple, once the last one is complete. Pour the silicone mix into the mold shape to cover the part by about a half inch. Now, you can choose to place the mold in a vacuum chamber and let it de-gas, or simply let it sit. I allowed this to sit, as the compound I'm working with has more than enough cure time to fully release all trapped air bubbles. Unfortunately, some of my components began to float as well.
Step 5: Remove the Mold Master and Prep for Resin
Wait! Make sure you've let the silicone cure for the necessary time.
Now that the mold is complete, you can remove the master part and prepare the mold for casting. In my case, since i'm mostly making single-part molds, i liberated the master parts with a scalpel (as not to create any holes in the mold larger than what would stay together on it's own) and cut the pour-holes for casting. The places where the supports had been also became pour holes and/or air vents. Be sure that your pour hole is at the exact top of the part, otherwise bubbles will form!
Step 6: Mix and Pour the Resin!
Mix the resin according to instructions in a fresh cup with fresh stir-sticks. As always, be safe, wear gloves, and mix in a ventilated space. Then, (working fast) pour the resin into the molds. Make sure to let the resin flow in, and any bubbles pop out, continue to pour after they do so the entire mold fills up. You'll know after if bubbles formed, or if the mold shapes were bad.
After pouring, i immediately placed it into the vacuum tank to pull all the remaining air out.
Step 7: Liberate the Final Parts
Once the parts have cured, we can remove them from the molds (the same way we did for the masters) and see our new cast parts... or failures. Trim and sand the mold spouts as you see fit, and enjoy! If large bubbles form or the cavity doesn't fully fill, try re-making the mold or changing the shapes of the pour holes.