Manufacturers love Bridgeport mills, particularly those machines that were made in Connecticut prior to 2002. Many of these mills have been in service two decades or more. Over the course of time and regular usage, it’s expected that some condition issues will arise, and that those issues will be addressed through prompt repair or refurbishment.
[[image:275423a.jpg|left|medium]]If you’re in the market for a used Bridgeport, you need accurate information about the milling machine’s condition in order to make an informed purchasing decision. Here are the top four areas of concern:
The ways, or mill bed, can become worn and uneven over prolonged, heavy use. The condition of the ways is often immediately obvious to a skilled observer: there will be pronounced areas that have been worn smooth and are no longer flush with the remainder of the ways. The absence of scraped lubrication channels is a red-flag sign that refurbishment is needed.
Worn ways can be addressed through chroming and rescraping. Once this refurbishment is completed, the typical Bridgeport mill is capable of delivering many more decades of reliable service.
The Ball Screws
The expected life that one will see from the ball screws is entirely dependent on what type of material has been worked on the machine. Working cast iron, for example, will wear out a Bridgeport’s ball screws on a fairly predictable timeline, while a Bridgeport that’s been used to mill aluminum or non-glass plastics might never need ball screw and nut replacement.
As a buyer, you want to know what type of materials have been worked on the machine, as well as how heavily the machine was used. A Bridgeport that has been used strictly to produce prototypes or run only one shift per day may be preferable to a used production milling machine.
The Lubrication System
In addition to the ways previously described, it’s essential to make sure all components of the Bridgeport’s lubrication system are installed and working properly. Ideally, you should see all refurbished Bridgeport mills you’re considering in operation prior to purchase to ensure you’re content with the lubrication system.
The CNC Controls
Bridgeport mills have been produced for decades, and over the course of this time, the control systems have evolved. The earliest Bridgeports were manually controlled. Then, as technology advanced, we saw the first primitive CNC modules installed. You can still find Bridgeports out there that accept 3.5” floppy disks! Ask if the used Bridgeport you’re considering has been retrofitted to a USB drive or if it has a RS232 port.
You will also want to know the programming language of the Bridgeport you’re considering. As with all CNC systems, familiarity with the language is critical. EZTrak™ 2 or 3-axis CNC is great for those who are already comfortable with it. (Photo above shows an EZTrak equipped machine)
Some machinists may prefer a different control system. ProtoTRAK™ control systems are very common on Bridgeports, as are Centroid and Anilam. As a buyer, you will want to know what system is in place, when it was installed, and how well it operates.
Bridgeports are our specialty!
As used manufacturing machinery brokers, we have a particular appreciation for the quality and character of Bridgeport mills. If you’d like to acquire a used Bridgeport, or if you have one you’d like to sell or have rebuilt, give us a call. We are in touch with former Bridgeport craftsmen who will refurbish mills. We specialize in connecting buyers and sellers of used manufacturing machinery. Here’s how you get started.