Julia Longtin •
04/03/2016 at 15:04 •
Tightening up the scope of the project to just the aluminium casting techniques.
pizza cat •
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.
Julia Longtin •
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 **