Sterling machinery carries all types of New & Used fabricating, Metalworking, and Chipmaking machinery. Machinery Like Press Brakes, Lathes, Shears, Plate Rolls, Angle Rolls, Saws, Cold Saws, Vertical Band Saws, Horizontal Band Saws, Shears, Tube Benders, Grinders, OBI Presses, Hydraulic Presses, Drills, Heavy Duty Industrial Equipment, Vertical Mills, Horizontal Mills, Surface Grinders, CNC Machinery, Blast Cleaning Equipment, Vibratory Equipment and much more! We carry brands like Wysong, Niagara, Bliss, Clearing, Timesaver Belt Grinders, Amada Press Brakes, Amada Shears, Leblond Lathes, Clausing Lathes, Bridgeport Mills, Scotchman, Federal, Clausing Metosa, Hardinge, Dake, Hannifin, Greenerd Presses, Rousselle, Haeger, Brown And Sharpe, Blanchard Grinders, Cincinnati Press Brakes, Chicago Dries & Krump Press Brakes, Box and Pan Brakes, Di-Acro, Pacific Press Technologies Press Brakes, Denison Hydraulic Presses, Benchmaster Punch Press, Kenco, Minster Presses, Monarch Lathes, Webb Rolls, Lown rolls, Wysong Rolls, Wysong Shear, Pines Benders, Leblond Lathes, Powermatic Band Saws & Drills, fabricating equipment, forming, forming equipment, metalforming equipment, metal forming equipment, Pacific Press Technologies, Pacific Press and Shear, pressroom equipment, pressworking, press working, press brake, hydraulic press, and many more. Give us a call today!
9310 Garvey Ave.
S. El Monte, CA 91733
The Bridgeport Milling Machine - Then and Now
The earliest Bridgeports were the famous "round arm" machines. This describes the top overarm which was a long round casting which the head was mounted to. The latter models have a dovetail slide in their place. Hence the name "dovetail overarm machine". Most round arm machines had the M-head, 9" travel knee, and a 32" table. As the years passed a 36" table was introduced followed by a 42" and lastly a 48" table. The knee travel was increased to 12". The heads went from the 1/2hp M head to a 1hp J head to a 2hp 2J variable speed head. The Bridgeport of today would have a 2hp 2J head with a 48" table and 12" Y axis travel.
Along with the different sizes, "chrome ways" were introduced. The hard chrome plating of the ways is a very effective means of extending the life of the way surfaces.
The first Bridgeports were equipped with grease fittings as a means of lubricating the ways. The introduction of the one shot lube system greatly improved the lubricating of all of the critical wearing surfaces and parts. Today the use of an automatic lube pump, which is on a timed cycle, improves the lube system still further.
The early power feeds on a Bridgeport were large heavy gear boxes that had to be manually shifted for every feed rate. These power feeds were so heavy that over time were known to actually put a bend in the table. Another drawback was that they were only designed for the table (X axis). The power feeds of today are very light, infinitely variable units that are available for any axis x, y, or z. These units are also equipped with a rapid traverse button and some even have a rotation counter built in.
As we came into the 21st century with Bridgeport feeling the pressure of imported copies, a licensing agreement was made with Hardinge Inc. In 2002 Hardinge Inc. moved the production of the famous Series I knee mill to its headquarters? in Elmira, New York. Two years later Hardinge Inc. acquired the Bridgeport brand and took over the entire line of mills and CNC machining centers. On solid footing and now as part of the Hardinge Inc. family, Bridgeport will continue to grow with innovative and productive milling solutions.
Specifications of Today's Bridgeport
Table Travel (X-Axis)
Saddle Travel (Y-Axis)
Knee Travel (Z-Axis)
Table Length & Width
T-Slot Center Distance
3 @ 2.5"
Weight of Workpiece (Max.)
HP Rating 30 Minute Duty Cycle
HP Rating Continuous
Feed Screw Diameter
Feed Screw Pitch
Vari Speed Range High Gear
500 - 4200 rpm
Vari Speed Range Low Gear
60 - 500 rpm
Power Quill Feed (3) Range
.0015", .003", .006" /rev
8.2' x 5.3'
Machine Shipping Weight
Bridgeport Milling Machine Serial Numbers
The machine serial number is located on the knee casting. Standing in front of the machine, crank the Y axis handle to move the saddle to the rear of its travel. The sliding guards will move to the rear exposing the stamped number. Most serial numbers start with a "12/BR" which signifies a 12" Y axis travel, however, for earlier machines, pre 60's, the serial numbers start with "BR" which signifies a 9" travel.
The numbers were started in 1938 with #1 and today are close to the 300,000 mark. The 50,000 mark was passed in the 1960's and the 200,000 mark in the 1970's. The 1980's and 1990's have brought the numbers close to the 300,000 mark. Along with the machine serial number each milling head is numbered. They are stamped on the main housing and also on a tag on the upper drive. These numbers are prefixed with the model of the head. The most common are "M", "J", "2J". The M model is a 1/2hp older head that was out of production sometime in the 1960's. The J head is a 1hp V-belt drive head that was the main work horse for many years. The 2J variable speed head was first introduced with a 1 1/2hp motor. This was later changed to a 2hp motor. The 2hp heads have a \2 at the end of the head serial number.
The following is a breakdown of machine s/n's in relation to the dates manufactured.