Rockford millers were made by the Rockford Milling Machine Company of Rockford, Illinois, USA. The company's "Hand Miller" range consisted of three machines, the No. 1, No. 2 and No. 3. A simple affair, without an overarm, the No. 1 was only capable of stub milling. The longitudinal feed, normally fitted with both screw and lever operation, was 10 inches, the traverse, by screw feed, 4 inches and the vertical travel of the 13.5" x 4" table 6.5 inches though a lever. All feeds were by hand - there being no power-feed option available.
To exactly the same specification as the No. 1, the No. 2  miller was no bigger or heavier; however, it did have an overarm, allowing it to be used for proper horizontal milling. Based on the same body castings as the No. 1 and No. 2 millers, the No. 3 was offered with the option of a longer (18" x 4.25") power-feed table with an inch more travel than the standard 10 inches of the hand-feed version. The casting at the end of the overarm support was formed into a rotating flange on which could be mounted either a plain vertical head, or a slotting attachment. The attachments were often driven in an ingenious way - and one that was not always illustrated in the company's advertising literature - with the drive from the spindle lifted by gears so as to pass through a hollow overarm support. In comparison with bolting the vertical and slotting heads so as to be mounted concentric with the main spindle, this arrangement immediately improved the clearance beneath the cutter and allowed the construction of a large clamping area to improve the rigidity of the fixing. The spindle on all the smaller models was hardened and ground and ran in plain, cast-iron bearings - a ball race taking the spindle end thrust; larger models used tapered, bronze bearings.
By the early 1900s The Rockford Milling Machine Company had merged with another to become the Sundstrand Machine Tool Company and for many years they made large horizontal milling machines, production bed mills, and ordinary and specialised lathes. During the 1930's they turned their attention to the development of hydraulically-powered, speed-control technology that evolved into the constant-speed drives used on almost all large aircraft for their electrical-power supply. Unfortunately, the company finally closed its doors in the early 1990s - yet, happily, the Sundstrand Aviation Company still exists (in 2001) as a division of United Technologies.