Steptoe, McFarlan and Co
of the Western Machine Works, Cincinnati
The business was started by British immigrants John Steptoe and Thomas McFarlan, some time between 1845 and 1853, when they were known as Steptoe & McFarlan or Steptoe & McFarland. The partners formally established their business in 1858, and this is apparently when they became Steptoe, McFarlan & Co.
The VintageMachinery.org website provides and excellent source of information on the company
Made woodworking machinery, shaping machines, and lathes. Their first lathe was said to be a copy of a Putnam lathe.
From 'English & American Tool Builders' by Joseph Wickham Roe, 1916:-
By 1870 they employed about 300 men, some of whom went on to establish their own businesses (including William Lodge, Thomas P. Egan, William E. Gang, Mr Oesterlien, and Mr Dietz).
On Steptoe's death in 1888, Thomas P. Egan (administrator of Steptoe's estate on behalf of his widow) sold the business, apparently to Otting and Lauder, with the stipulation that the John Steptoe name should be retained. The John Steptoe Co subsequently made shaping and milling machines.
'Steptoe's name should be remembered, for Cincinnati tool building owes its start more to him than to anyone else, with the possible exception of William Lodge, who was himself one of Steptoe's workmen.'
Sources of Information
-  vintagemachinery.org, Steptoe, McFarlan & Co.