Only aluminium and non-ferrous metals? Indeed, for these millings machines were the product of a company famous, since its founding in 1915 in, Niles, Illinois, for woodworking machinery. Just as with certain models from the well-known  English maker of wood machinery, Wadkin, some Woodworking machines do lend themselves to the machining of softer metals though occasionally more resilient materials can be handled as well. Onsrud also manufactured metal-working machinery for the aircraft industry, a typical example being a huge gantry skin miller 12 ft wide and 90 ft long. The bed sections were made of steel plate, two or more inches thick bolted together and carrying ways of hardened steel sections that were also bolted on together with the gear racks. The Gantry moved on recirculating roller bearings, the drive being by hydraulic piston motor. Also produced were copying lathes, examples of this type being used in the Springfield Armory to manufacture rifle butts.
Based in Chicago at 3900 Palmer Street - the large brick-built factory with its glass-block windows, a hint of Art Deco decoration at the roof corners (and with the original entrance door still surviving) Onsrud had several patents to its name, some these being taken out between 1921 and 1960 by members of the founder's family: Oscar Onsrud, Rudulf F. Onsrud, Karl Onsrud and Charles R. Onsrud
In 1968, in order to obtain their metalworking machinery, Onsrud was bought by another Chicago-based company, the punch-press maker Danly Machine Corp. In the early 1980s Danly - having presumably lost interest in the wood machine side of the enterprise, sold this to two employees. At some unknown date, the name Onsrud was changed to Onsrud Machine Corp. - a press release on the Advanced Technology Services website reported that "Advanced Technology Services has acquired from Onsrud Machine Corporation all inventories, documentation, manufacturing and marketing rights for all Onsrud woodworking and metalworking machines previously manufactured and sold by Onsrud Machine Corporation in Wheeling, IL. ATS is now the source for replacement parts and repair service on all existing and newly purchased Onsrud machines."
Today? See today's continuation of Onsrud wood machinery here:
https://www.youtube.com/watch?v=dXBIKDdUrow

The Onsrud factory door in 1943