I’ll show you how I make plastic parts into metal using a lost wax process. You can make shapes you make yourself into metals such as tin, pewter, aluminum, lead, silver, gold, and other metals. Here, I'm using tin.
Before we begin, most importantly be careful and use good judgment, Melted metals are very hot and can severely burn you.
Not all of us can afford metal printing 3D printers, and I propose we don’t have to or want to. For the price of the metal, beeswax, and some re-usable molding materials, you can make your own metal castings from your plastic parts. And the process is straight forward after you do it once.
Step 1: What You Will Need for DIY Metal Casting
You will need your mold making materials, ComposiMold or ImPRESSive Putty. We will first show you the ComposiMold, but at the end of this video we will also show you the ImPRESSive Putty. Both are reusable. The ComposiMold is a heat and pour and will pick up great details simply by pouring. For the ComposiMold, use either the ComposiMold-Original or the ComposiMold-Flex so you can bend the rubber mold around the wax without causing damage. Also, for the ComposiMold, you will need to chill your mold prior to pouring in the wax. You cannot use the ComposiMold for microcrystalline waxes because of the higher temperatures. Use ImPRESSive Putty instead.
The ImPRESSive Putty is a heat and press material that is extremely easy to make molds with, but is firmer, so you may need to make cuts in the mold to remove the wax without breaking it. However, if you use ComposiMold instead of the wax, you will not have any issues. We’ll show you that in another video, but trust us, it’s pretty cool. The ImPRESSive Putty can handle higher temperatures so you do not need to chill the mold first. Other materials you will need to make your metal casting using the lost wax process is a wax. I like beeswax, but you can use microcrystalline waxes with the ImPRESSive Putty. You can experiment with other waxes as well. A metal. We’re using tin. Higher temperature metals such as steel are likely out of the temperature range you can do in a DIY environment. ComposiMold Plaster. ComposiMold plaster contains an additive to make good strong molds in and around ComposiMold. Torch. If you have a high temperature oven that will work too. Something to hold the melted metal in. I use a small crucible. Pliers to hold the hot metal Eye protection, hand protection, and body protection. Please be careful. This is dangerous if not done with care. And some random containers and stir stick Plus an oven, and a fire extinguisher for safety is also a good idea. Do this in a well ventilated area. If in doubt, do not do it.
Step 2: Make or Use an Original Shape
And of course you need your original shape. We are using a 3D printed eagle that we found on thingiverse. This is an awesome collection of models and designs. Download the file, copy it over to your 3d PRINTING software. We scaled this guy down to about 1/3rd the original shape. And then I printed it with our 3D printer.
Make a mold of your object so you can make a wax casting so you can make a disposable plaster mold that can handle the heat of the metal.
It’s much easier than that sounded, so let’s start. Melt the ComposiMold in the microwave for about 40 seconds for a small amount. Make your rubber mold by pouring ComposiMold around your object. To stop this eagle from floating I could hot glue it down, but instead I poured a little ComposiMold into the cup and let it solidify. Then I poured the rest of the ComposiMold over and around the object. The already cool ComposiMold holds the eagle in place. To cool this faster, I placed the mold in the freezer.
After solidified, in about 20 minutes, I pulled off the mold box container and pulled out the original. Many people like using Legos to make the mold boxes. In this case a cup worked fine. The ComposiMold mold is ready to for the wax.
Step 3: Make Wax Casting, Chill Your Mold Before Pouring in Beeswax
I want the mold to be cold when I pour, so while the mold is still cold being in the freezer, I melted the beeswax on the stove at about 200 F and poured it into the mold. Let the beeswax cool so it is on the edge of solidifying again to reduce any possible melting of the ComposiMold. Let it cool to around 165 F. And be sure the ComposiMold is chilled when pouring. The wax will cool from the outside in, so it will chill in the correct shape.
After this cooled in about 15 minutes, I removed the wax eagle from the ComposiMold.
If I was making beeswax candles, this would be the finished product. And it is very nice.
Step 4: Now the Plaster Casting From the Wax
Now we make the disposable ComposiMold plaster mold using the wax Mix the ComposiMold plaster with water at about 2.5 parts by weight or volume plaster to 1 part water. I typically just eyeball it and make it as thick as possible while still being pourable. Place the wax eagle into another mold box, or cup.
Pour the plaster around the wax figure and let solidify for at least an hour. Two hours or even overnight is better.
Cut away the mold box to Remove the plaster mold from the cup and Now comes the lost wax process. The eagle wasn’t quite on the bottom of the mold box so I chipped away a little of the plaster so I had a hole to pour out the wax and pour in the metal.
Step 5: Melt Out the Wax
Flip the mold upside down and melt out the wax. I use a few stones to keep the mold up in the air so the wax can come out. You can reuse the wax as well. I melted out the wax at 350 F in an oven for about 20 minutes. Don’t let the wax overheat, it can catch on fire.
After the wax is removed, continue to warm the plaster to remove more water. You also want the mold warm when you pour in the metal so there is less temperature difference between the plaster mold and the metal. This is especially true for higher temperature metals like aluminum or silver.
Step 6: Melt the Metal and Pour Into Your Plaster Mold
Now the last casting step, melt the metal. The tin can be melted with a butane torch. You may need an insulated oven to melt higher temperature materials such as aluminum. I've melted aluminum with the butane torch, so you can do it.
Clean off the top of the tin. I used a handle of a spoon to scrape off the top layer.
Carefully pour the metal into the plaster. Definitely wear eye protection and you should also where heat protection for your body and hands. The metal can splatter and cause serious burns.
Let the metal cool in the mold. You may want to quench the metal to create a different microstructure in the metal, but I did not for this. I let it cool for 1 hour.
Step 7: Break Away the Plaster Mold, Clean Up Your Part, and Admire
Using a chisel or screwdriver and hammer break away the plaster and admire your metal casting.
Final Tin Eagle. Ready to go.
Thank you for reading, let me know what questions you have and any comments.