Hard to tell unless there are any data that states start end end of production. I would expect it to be 1930s and older. Even though chrome details on the machines were standard (knobs, levers, face plate, ect), the feet were often nickle plated, or other type nickle coating I'm not sure how they did it. By the 40's and closer to the 50s all original accessory boxes I've seen have been chromed, and the basic stitch foot hinged. In the 1930s I think it still was one piece metal and nickle finish.