This is a pattern for a piston. I just have the first coat of spray paint on it so far, but tomorrow promises to be a nice enough day to possibly cast something, and this may be the first trial of the newly lined iron furnace, final paint coat, or not.
This pattern is a single piece, rather than split. It is hollow and has draft on the outside and the inside of its semi-conical shape. These were turned into the blank by offsetting the topslide on the lathe.
Instead of a parting line along the horizontal, like the split cylinder pattern, it will be cast upright with the parting line at the widest end. The hollow is intended to produce a greensand core when making the mold, in lieu of a hard core. What looks like a core print on the far end is actually a feature of the intended casting, to be used as a chucking piece when machining the piston in the lathe.
So this piston pattern illustrates different features and approaches to casting requirements when compared to the cylinder pattern, even though they look similar.
