291 Head Differences

[JohnZ]

To be more precise, high-volume castings had multiple PATTERNS (made of cast iron or stainless steel); when sand was packed around the pattern, it created a sand mold. The sand mold was opened, the pattern was removed, and the mold was closed. Iron was poured in the sand mold, and the sand disintegrated on the "shake-out" table after cooling, when the raw casting was removed.

Each pattern was numbered and carried the casting number, casting date and hour clock; that appeared on each casting, and enabled internal traceability in the foundry back to the pattern in the event of a problem with a casting.

The casting number, casting date, and pattern number were individual brass characters soldered to a brass plate that was pinned or screwed to a recess in the pattern; the date tag was changed every day, and the clock tag was changed every hour. Photo attached of tags from the Saginaw Foundry.