Casting Update

There’s been a lot of interest in our aluminum casting efforts.  We’ve stepped things up to our first lost foam casting exercise that ultimately resulted in failure with a lot of learning in the process:

Using a foam blank machined on the CNC mill, we first start by burying half of the foam in oil bonded sand:

Once we’ve filled half of the box, we flip it over and fill the other half:

Adding a funnel for a spot to pour the aluminum into (sprue) and a pipe for a vent on the opposite side of the part:

Then we moved the ready to pour mold near the kiln, on top of a sand bed that will catch any spilled aluminum and prevent it from touching the concrete:
At this point the aluminum was nearly molten, so we added some more segments to fill the crucible with enough stock for the pour:

A short time afterward, a wrench appeared in our plan:

our free kiln had been previously repaired with electrical tape, which until now had held.  Unfortunately, our melt wasn’t up to temperature but our kiln was now running on a single coil, which wasn’t able to raise the temperature, so with molten metal not getting any warmer we went ahead and poured anyways (there’s nothing else you can effectively do with a molten crucible but pour it out someplace):

As expected, our gate froze almost immediately and didn’t allow any additional metal into the casting, so we poured the vent and excess went into the ingot mold:

The resulting end sections of our cast came out with very good surface finish but with lots of oxidation defects from the incorrect temperature and hurried pour.  We’re looking forward to another attempt in the next week or so :-)

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