Introduction: Entwined Hearts Cast in Aluminum
I had just finished building a metal casting furnace and needed to make a valentine's day present for my wife. I found his idea and decided to translate it into cast aluminum. I used a technique called lost foam casting which involves pouring molten metal directly on a pattern made out of foam. The foam vaporizes and the metal fills the void creating the casting. I hadn't tried it before but it's supposed to be fast and easy and involves fire. Who doesn't like that?
Step 1: Cutting the Pattern
Attachments
Step 2: Preparing to Cast
You can do lost foam casting in a number of ways. I chose to just bury my pattern in loose sand. This is the easiest and most immediate method but it gives you a grainy surface from the sand. I knew I was going to do some finishing to my castings so I didn't mind. I sifted regular play sand into an old soup pot and buried the first heart up to the top of the sprues. Then I took a short can with the top and bottom removed and put it around the entry side. The can acts as a collar to retain the metal and gives you an extra supply to help fill the mold as you are pouring. You also don't have to be quite as precise as you pour.
Step 3: Pouring
Step 4: The Second Pour
Step 5: Finishing
Now it's just a matter of removing the sprues and finishing the surface of the hearts the way you like. I used a saw to cut them off as close to the top of the hearts as I could. Be careful not to cut too much off. Next, I used a grinder to rough shape the tops. I used a file to do the final shaping and to smooth the surface somewhat. I wanted to leave the ridges in the hearts but also have them be smooth enough that they invite you to handle them. Finally, I used 120 grit sandpaper to take out the file marks and 600 grit to get the final finish. This was my first real cnc project and my first casting. I was very pleased with the result and my wife liked her present too.
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