The ball bearing saw guides and “straight” bracket feet are indicative of a late 1930’s model. Observe also the spring loaded elevator stops, which release into a groove at the bottom of the saw guide. This feature was to be adopted by, and would remain with, all subsequent Langdons until the very end of production in the late 1960’s or early 1970’s. Compare this to the Craftsman 3650.
Photos courtesy of Omar Aguilar, of Hialeah, FL.
References:
A Langdon Mitre Box Reference 