Hey everybody! Lately I have been watching many of videos involving molten aluminum and I wanted to go ahead and try casting something myself. The possibilities are endless with this stuff and you can literally make whatever you want out of solid aluminum! In this tutorial I explain how you can get started and start casting at home using the lost foam method. In this tutorial I will be casting my own YouTube play button.
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Step 1: Watch the Video!
Before you read the rest of this instructable you should watch the video that I have posted below. The video quickly and clearly demonstrates the process of making aluminum castings at home while spending reasonably low amount of money! In the video I make my own YouTube play button using some scrap aluminum and cheap supplies that are very easy to get a hold of. The silver YouTube play button is an award that YouTuber's get for surpassing 100 000 subscribers and I thought that it would be a cool thing to try and replicate. Also, if you enjoy the video I would appreciate it if you hit the like button and consider subscribing to my channel. I also post all of my builds here on instructables so you could also follow me there!
Step 2: Make a Mini Metal Foundry
Before you can melt down some scrap aluminum and start making castings, you will need something to melt some scrap aluminum with. The easiest/cheapest way to make your own mini foundry is to follow Grant Thompson "The King of Random's" tutorial. Grant uses cheap materials that you can find at any hardware store. You can also find some of the materials at the dollar store and even your local thrift store. Instead of explaining how I made my mini foundry I will post the link to his video below. I used the exact same method that Grant used and I couldn't explain it any better!
Step 3: Making the Mold
Once you have made your foundry you can get started with making a mold! The materials that you will need to do this are:
- Play sand
- Wooden box or steel bucket
At this point you will need to get creative. You will need to make an exact replica out of foam of what you want to turn into solid aluminum. As mentioned in the video, the method of casting that I am using is known as the "Lost foam method". The lost foam method is a type of evaporative pattern casting. This process takes advantage of the low melting point of foam (240 Deg C). Once the molten aluminum is poured into the mold, the Styrofoam quickly evaporates and the aluminum takes its place, simply replacing the Styrofoam with solid aluminum. The melting point of aluminum is approximately 660 Degrees C.
In my case, I wanted to replicate the YouTube play button. So I started off by printing off a template and I glued it onto a thin piece of Styrofoam. The foam that I used was from a display board that I purchased at the dollar store. After that I cut out the middle of the play button and then cut around the edges. While I was doing this I realized that the scissors were leaving a rough edge on the foam after I cut it and I wanted to keep the edges smooth. I found that using a soldering iron was the best way to slice through the foam while keeping the edges nice and smooth. If you try this make sure to wear a mask because the melted foam leaves behind some pretty nasty fumes!
After that first piece was cut out, I glued it onto another thin piece of Styrofoam and cut the edges to the same size of the first piece. Once that was done I peeled the paper template off the front and glued two thick pieces of foam onto each side on the back. These pieces were about 5 inches in length and 3/4 of an inch in thickness. These pieces on the back will be used as the sprues.
When you are finished with your Styrofoam pattern it is time to pack it into a box or bucket using some slightly damp play sand. Making the sand a little damp will help hold the sand keep its shape after the foam melts away. When you are packing your pattern into the sand you want to make sure that you are leaving no air gaps around your foam pattern. Once you have your pattern packed tightly into the sand you will want to add a soup can with both ends opened up over one of the sprues. This is where the molten aluminum will be poured into. The can will fill up with the molten metal before the foam melts away. This ensures that pressure gets kept onto the foam pattern. The other sprue will be used as an exhaust port for fumes and any excess aluminum.
Step 4: Pouring the Aluminum
Now that you have a mini metal foundry and a pattern packed into sand, there is only one thing left to do! You will need to get yours hands on some scrap aluminum. When I first started on this project I thought that this would be the hardest part. But it turns out the aluminum is everywhere and it isn't hard to find! The most common way is to melt down empty soda cans. To get a descent amount of aluminum this way, you would need alot of cans. Instead you can go to used construction stores or even thrift stores. Look for things like cabinet handles, aluminum trim, heat sinks, and old electronic casings. You could even go over to your local high school and see if the shop classes have any aluminum scraps.
Once you get your scraps you can go ahead and fire up the foundry. The mini foundry runs off of charcoal so you should go buy some charcoal igniter to get it started quickly. After your foundry is on for a while the crucible will start turning red hot and you can start adding in the aluminum. The crucible that I am using is made from the bottom half of a fire extinguisher. After a short amount of time goes by you should see that the aluminum starts melting away. Once all of your aluminum is in liquid form your can turn off the hairdryer and prepare to pour it into your mold. BE CAREFUL, make sure to wear some proper PPE before you pour out the aluminum. I used a pair of old BBQ tongs to pour the molten metal into the mold.
Step 5: Finishing Touches
After about 5 minutes goes by the aluminum should have hardened up enough that you can pull it out of the sand. Make sure not to touch it because it is still EXTREMELY hot. I used a pair of channel locks to pull mine out of the sand and then dropped it into a bucket of water to cool it off.
After my play button was cooled off I noticed that there was sand marks all over it. I was prepared for this to happen. The marks were created from the play sand being so course. There is a special type of casting sand out there called "green sand" which is very find and it would not leave little indents like this. But I wanted to try doing a casting while spending a minimal amount of money.
All that I had left to do was give my YouTube play button a smooth and shiny finish and cut the two sprues off of the back. After some grinding, filing, sanding, and polishing, it turned out looking pretty awesome! I just used Brasso to give the aluminum a little shine, but a better thing to do is use a polishing wheel.
I hope that you all enjoyed this tutorial and that you learned a few things about lost foam casting. Thank you very much for reading this and watching my video!