Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

My next casting used a core, and the sand I used for the core was sandblasting sand that was adhered using a sodium silicate binder.
I thought the sandblasting sand would be sufficiently fine, but it turned out to be rather coarse material.

I did not know that the top of the flask had to be weighted, and so the mold halves separated, and the aluminum 356 partially ran out.

Lesson #2:  Add weights on top of the flask before pouring metal.
Lesson #3:  I made the pattern for this casting out of thin balsa wood, and that turned out to be a mistake because after several uses, the pattern broke into numerous pieces.  Don't make patterns from balsa wood unless they will be a one-time use application.

And although the core remained in place pretty well, but was not mechanically fixed in position in the mold, so it probably shifted a bit during the pour.

The top of the casting turned out fairly decent.
The bottom was another disaster.

At the time, I had no idea about how to set up gates, runners, riser, etc. in a more standard configuration that is often used in foundries.
Fortunately the exact setup of gates, runners, risers, etc. is not critcal, and I almost got a usable casting.