Home About Us Bridgeport Facts Quote (rebuild) Quote (purchase) Accessories Buy Online Ebay Store Contact

The Series I Brideport Milling Machine

Choose a Topic

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 the 1930's with #1 and today have passed 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 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.

1938 - 1950     1 - 11,378
1951 - 1960     11,379 - 46,938
1961 - 1970     46,939 - 131,778
1971 - 1980     131,779 - 206,297
1981 - 1990     206,298 - 257,888
1991 - 1995     257,889 - 267,636
1996 - 2000     267,637 - up

Various Machine Models & Sizes
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 42" or 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.
Back to top