The 315-model numbers were/are made by Ryobi (web linkhttp://www.owwm.com/mfgIndex/detail.aspx?id=222)
Some machines sold by Sears Roebuck (including all machines before about 1930) did not use any of the Craftsman, Companion, or Dunlap names, but were branded simply as "Sears, Roebuck & Co." An example is a scrollsaw made by Syncro.
Makers of Wood-working Machines, Metal-working Machines, and Stationary Engines for Sears
The list below contains the known makers of the above-mentioned products only. For a more complete list of makers of Sears products, see the section "Sears, Roebuck Number Prefixes", below.
Sears Roebuck introduced wood-working machinery in their 1926 catalog, according to one source. Here is a list of known North American-based makers of their machinery with their model-number prefixes (some companies do not have a model-number prefix because they manufactured for Sears before they introduced the prefix system):
•American Floor Surfacing Machine Co. (207)
•American Machine & Tool Co., Inc. (149)
•Atlas Press (101)
•Belsaw Machinery Co. (306)
•Brown-Brockmeyer Co. (410; motors and grinders)
•Clausing Industrial, Inc. (534)
•Comet Manufacturing Co. (778)
•Covel Manufacturing Co. (108)
•Delco Products Corp. (397; motors and grinders)
•DeWalt Products Co. (900)
•Diehl Manufacturing Co. (315; motors and grinders; later products with 315 prefix were made by Ryobi and are outside the scope of this website)