After several attempts at casting parts, I visited the nearby Metal Museum located in Memphis, Tennessee, and they have foundry there.
I was very glad to meet these wonderful folks, and they filled me in on many of the do's and don'ts of metal casting, as well as showing me how to make bound sand molds.
This was a golden opportunity for me to learn how metal castings should be made, in order to get high quality castings, and this knowledge solved many of the problems I was having.