08/21/2014 at 05:54 •
Fresh baked molds. The one on the right used a more refined recipe and came out great.
We used a hairdryer to blow out the ash from the inside. You can use any form of compressed air.
Creating sprue extenders, used so that liquid aluminum causes pressure inside of the chamber. They need to be skinny & tall!
Attaching the sprue extenders atop of the mold. Good ol' duck tape can be used for this to keep out the sand.
Our sandbox with a small layer of sand on the bottom. Place the molds in the sandbox and then cover with sand until it reaches near the top of the sprue extenders.
Carefully pouring the aluminum.
Aluminum will burn through the sprue extenders. It is important to fill the box until the sand reaches near the top of the sprue extenders. Our box nearly caught on fire..
Taking our mold out of the sand. This is the most fun part of the process, seeing what is inside...
Chisling the plaster away with a screwdriver or whatever you got.
you have a part to remove from its mountings! This part came out great!
However, we learned a lot about the mounting of the part when
attempting to remove it. That will be covered in the next project log.
08/20/2014 at 21:31 •
We're going to microwave out our molds. Here's some science about whats happening.
Two important stages:
Stage 1: Remove all water - will sweat profusely the water content in the form of vapor - may need towel to keep microwave from flooding.
 Warning  Use safety precautions! We did this outside and stood atleast 30 feet away from the microwave.
During this stage, we have seen conditions where the mold could split and explode. This was mostly in part due to heating the water in the mold too rapidly in one spot. The microwave that caused this problem had no spinning plate. This is bad because then the microwaves will target one particular point and will begin to overheat the mold. We observed a chain reaction when this happened. Once a section of the mold began to overheat, a hot-spot forms and it grows as it absorbs microwaves at a higher rate [becoming a susceptor!]. This is what caused Porygon's brains to blow out of the mold and become captured in aluminium.
It was hard to capture the smoke escape the mold. Microwave in short bursts starting at a lower temperature.
We set our microwave at 50% [1100 watts] and zapped it in short bursts of around 5 to 15 minutes on average.
The investment will of evaporated and start smoking (non-profusely). The susceptor absorbs the microwaves at a higher rate at which the contents from the mold incinerate and create the cavity inside. Make sure that no plastic is visible in the bottom of the sprues and wells and use a form of compressed air [we had a hairdryer) to blow out the ash and residue from the inside.
You're ready to move onto the next step when the mold has been cleared of ash and residue, making aluminium!!
** Don't reuse the microwave for food again **
08/20/2014 at 18:54 •
Investment [mold]: Equal parts of Perlite / Plaster of Paris / Water
Something to stir with and a bowl to stir in
Old plastic Tupperware
Vibration table of sorts [to remove the air bubbles from the container]
It took about 3.5 cups of each ingredient equally in order to fill our mold.
Mix "investment": equal parts perlite + plaster of paris + water. Mix dry ingredients before adding one part water (equal to the perlite or the plaster). Investment should have the consistency of thick soup (think: pancake batter). Do not stop stirring for more than 15 seconds after you add water or the investment will harden. Stir until ready to pour, then pour quickly! You're looking for a thick soupy consistency like pancake batter.
Pour a little investment into the container to server as a 'floor' for the object to rest on.
Place the object on top of the investment.
Cover the object with the remainder of your investment, until the object is no longer visible.
You will want to vibrate the mold with the container so that the air bubbles inside can escape. We might try to use a laundry machine next time and see how that goes.
We added a little weight atop of our mold while the investment hardened. Set for ~ 1 hour.
We had accidentally got Tupperware that was too firm it caused a problem to remove the settled mold.
Use older / plastic Tupperware that has flex and wiggle in it so that after the 'investment' has settled you can remove it easier :)