My Failed Attempt at (Showing) Love

Project:
Show my wife how much I love her by custom casting a beautiful heart

Process:
So even though we don't do valentine's (see Mel's blog at http://www.mel-eigenheer.blogspot.com/2012/02/anti-v-dayness.html for more details), I wanted to try my new foundry furnace and make something other than just plain old boring ingots (even though Nathaniel LOVES to play with aluminum ingots!).

I found an elegant scroll-saw pattern online of a heart I wanted to cast in aluminum and printed it out on paper. Since I threw out my carbon paper a year ago I had to find a way to trace the outline on my 1/8" piece of MDF.

I covered an area of the MDF with aluminum tape, and traced along the outline of the heart. The pen made an impression on the aluminum tape which I could then follow with the scroll saw. Once the heart was cut out, the arduous job of sanding started. With the help of a dremel and some sand paper I smoothed all the surfaces and gave it about a 5 degree angle to make the pattern easier to remove from the molding sand.

Next came powdering the pattern with talcum powder and filling up the drag with sifted green sand. After rapping it with a hammer, I flipped it over, covered the surface with some more talcum powder, then filled the cope with green sand, stuck in a pice of pipe for the sprue, took it all apart again and cleaned it up. Once all the sand was cleaned, the feeder was cut, the mold halves were combined again.

After about 25 minutes I had some good molten aluminum. This time I used a 50:50 ratio of NaCl and KCl as flux (making the aluminum more liquid) and some Sodium Bicarbonate (Baking soda) to de-gass the liquid aluminum. Finally, I was able to pour my first casting, after about 10 minutes I took it apart with anticipation and to my disappointment, the mold had barely started to fill, let alone fill the entire shape.

In retrospect I could have guessed that the 1/8" high channels the pattern left in the molding sand was too small for the aluminum to flow through before it solidified. Now I'm gonna have to make a thicker pattern. I'll try one at 1/4" and see if that works, next time I have a chance to go fire up the furnace.

Pictures:

Pattern printed out on paper

1/8" MDF with aluminum tape ready for tracing

Traced heart on the aluminum tape

Cut out heart before the aluminum tape was removed

Pattern in the green sand with the sprue pipe

Cope and drag both filled with green sand

Mold ready for casting

After the casting had cooled down

Failed!

Tools:
Foundry furnace, hammer, scroll saw, dremel, make-up brush, ss strainer

Materials:
1/8" MDF, two scroll saw blades, sand paper, talcum powder

Cost:
$0.00

Time:
2hr

Conclusion:
Failure, the mold cavity was too thin