Bridgeport
The original corporation was founded in Bridgeport, Connecticut and started selling its machines in 1938. It became famous in the following decades for small- and medium-sized vertical milling machines, with an iconic form of quill-equipped multiple-speed vertical milling head with a ram-on-turret mounting over a knee-and-column base. The American Precision Museum's biography of Rudolph Bannow[1] reports that he conceived the iconic design in 1936 as the logical machine on which to mount the milling head already being built by the Bridgeport Pattern and Model Works (which he owned with partner Magnus Wahlstrom). The first Bridgeport milling machine (serial number 1) is on display at the Museum.[2]
The company’s manual milling machines have been so successful that the term "Bridgeport" is often used to refer to any vertical milling machine of the same configuration, regardless of make. Many other companies have cloned the form. Today the Bridgeport brand still produces this configuration in both manual and computer numeric control (CNC) versions, although tool-changer-equipped machining centers are now equally prominent members of the product line.
Bridgeport manual milling machines have come in many types and sizes over the years, including (but not limited to) the C head (original), R head (heavy duty C head), M head, J head (and high speed, 5440 RPM version), 2J1 1/2 head (1.5 HP Vari-Speed), 2J2 (2HP Vari-speed), and Series II head (4HP Vari-speed). All of the heads offer variable speeds, the earlier ones via a step pulley (cone pulley) and the later ones via either continuously variable transmission (CVT) systems or variable-speed drive. Typical table sizes are 9″ × 49″ (Y and X, respectively) and 10″ × 54″. Machine tapers for toolholding include Morse tapers (on early models) and the R8 taper (a widely used standard that Bridgeport created) on most models. Both Morse and R8 allow for both collets and solid holders; and a drill chuck can be held by either of the latter. Machine slides are of the dovetail type, and rotary bearings are mostly of the roller and ball types.
