Mold Making Highlights
Here you can see the LFMC manifold pattern that will be our next victim.
The pattern is placed on the molding board in the drag half of the flask. This flask is almost too small for this pattern, but I'm cheap and didn't want to build a new one just for this experimental casting.
Facing sand is riddled (I use a 1/4" mesh riddle) over the pattern to provide good conformity to the pattern details.
Once the pattern is covered with finely riddle facing sand and rammed about half full, plain molding sand can be added to fill the remainder of the drag.
Once the drag is filled with molding sand and rammed uniformly, the surface is struck off level to the drag frame and a bottom board is rubbed in.
The drag is then rolled over revealing the pattern firmly set in the drag portion of the mold.
Parting dust is sprinkled over the entire face of the drag to prevent the cope section of the mold from sticking to the drag section. This allows the two halves of the mold to be separated without damage to either one.
Because the top of the pattern is essentially flat, the cope is simple and there is no real detail work involved in ramming it up.
Once the cope is rammed and lifted off the drag, the gates and runners can be cut into the drag to provide pathways for the molten aluminum to flow into the mold. Once these are added, the drag half of this mold is complete.
Once the drag is complete, attention is focused on the cope. Here, the sprues (larger holes toward the middle) and risers (smaller holes toward the ends) have been cut in. Though hard to see in this photo, several vent holes have been added to the cope to allow gasses to escape from the mold to prevent damage to the casting. These vents are made with a small wire tool that simply pierces the sand and leaves a small channel for these gasses to escape. Once these operations are complete, the cope is complete.
With the cope reinstalled on the drag and the flask latched closed, the mold is complete and ready to pour.