If you’re old enough to remember a time when none of the names of the machines in your shop had “CNC” before them, you are likely familiar with the Bridgeport vertical milling machine. In its heyday, the versatile knee mill was in a class by itself, allowing the machinist to do milling, drilling, and various other operations in a vise or clamped to the table using the t-slots. Most of the Bridgeport mills had power feed in the X-axis for various milling operations.
The original Bridgeport Series I model had a movable ram to increase the work area and a table designed to take on a larger workpiece. You could swivel the turret to reposition it to different angles so the part could remain firmly clamped when milling angles. The Bridgeport milling machine was an innovative and surprisingly rigid machine for its time.
In 2002, Hardinge, a well-known lathe manufacturer, purchased Bridgeport and continued making the Bridgeport Series I milling machine. Over the years, low-cost copies of the Bridgeport were introduced, many coming from overseas. However, most of them arrived on the scene without the rigidity and precision of the original.
Even if you have one of the original Bridgeport mills, it’s essential to understand that advances in technology make it possible to own a vertical CNC milling machine with the same quality and better features. These CNCs can boost productivity, enhance quality, and ensure repeatability, all at an affordable price. So, here are eight signs that you should upgrade your aging Bridgeport and reap the benefits of a quality CNC machine tool.
Why keep paying all that money to farm out work to a competitor when you could be producing those parts on your own CNC milling machine at a fraction of the cost? Whenever you subcontract work, you lose control over delivery and quality to some extent.
You also sacrifice the flexibility to make engineering changes as easily and inexpensively as you would in-house. And then there’s the matter of logistics: it can be costly to transport those products to and from the other shop. If all of that doesn’t convince you, think about the public relations disaster you might face if another shop messes up critical parts for one of your key customers.
2. You’re finding it harder to meet your delivery dates with a manual milling machine
The first thing people notice about CNC milling machines is how much faster they travel than the Bridgeport manual machines and how much deeper the cuts they can take. Also, the typical Bridgeport is more labor-intensive, meaning it’s more expensive to operate and will be more prone to the mistakes that can scrap parts and put you behind on your delivery schedule.
3. You want to grow your machine shop by taking on more complex work
Chances are you know your stuff; terms like collets, ram travel, spindle tapers, and quill diameter are all familiar from your extensive work on Bridgeports. But now you’re ready to take that knowledge and apply it to a new machine and supercharge your output. That’s where a CNC machine can come into play.
High-quality 3-axis CNC Bridgeport-type knee mills using machining software are steps above the manual vertical milling machine using an Acu-Rite digital readout (DRO) displaying only X-axis and Y-axis positioning.
The CNC knee mill can be programmed for face milling, angle cuts, form milling, profile milling, and many other operations, opening the door for machining complex shapes that are impossible on the Bridgeport mill.
4. You notice inconsistent quality when machining multiple parts on the Bridgeport
With CNC machining, machinists employ computer-aided manufacturing software (CAM) that enables the CNC machine tool to shape your workpiece to precise specifications. The software determines speeds, feeds, and depth of cut, along with the tool path, avoiding manual intervention by a machine operator.
Once a tool path has been designated and the milling machine is programmed, it runs as many parts as you need, all with the same level of precision and repeatability, making the process efficient and scalable.
5. You would like to start quoting competitively on production milling work
The versatile CNC knee mill is ideal for repair, prototyping, and production. And if you are looking to increase your workload and profits, the high-production capabilities of a CNC knee mill will help you get more parts out the door in the shortest amount of time.
In the days before CNC milling machines, production parts required expensive jigs and fixtures. Today, they need user-friendly software and someone to change parts!
6. You’re changing spindle speeds on your J Head Bridgeport mill with a step pulley
Although a step pulley design is cheaper and easier to repair for the hobbyist, it is time-consuming in a professional environment where time is money. The vari-speed head is faster and more convenient to change speeds, but it makes little sense to convert an old Bridgeport to a variable speed head. It’s better to upgrade to a CNC machine where the computer controls the vari-speed activity, and the machine provides multiple advantages for the company.
7. Engraving is currently a secondary operation for your shop
Many machine shops still use manual engraving machines to identify their machined parts. This method works, but it becomes a secondary operation, meaning extra setups and an increased possibility of human error.
CNC mill engraving utilizes the manufacturing software to create a computer-based tool path to produce a precise engraving without the extra setup and with less chance of mistakes as on the manual tool. Add a 4th-axis rotary table, and you can engrave round parts.
8. You want to get parts off the milling machine faster
Even if you are a jobbing shop and have no interest in pursuing production work, you still want to get your parts through the milling machine as quickly as possible. However, hand-cranking a Bridgeport Series I standard milling machine is not the answer. It generally results in worker fatigue instead of increased productivity.
Machinists doing monotonous work throughout their shift are prone to making mistakes or, worse yet, getting hurt. And scrapping parts or having work-related injuries is not the way to get work through the milling machine rapidly. Fortunately, you can speed up production and free up employees to concentrate on other projects. Here’s how!
If your Bridgeport is over the hill, this machine tool could add new life to your shop
The SUPRA CNC vertical knee mill from CNC Masters will make any shop more productive. This versatile machine is ideal for hobbyists, machine shops of all sizes, product development, high productions work, engraving, and teaching tools in vocational-technical schools and science labs.
Look at a few of the specifications for the CNC SUPRA 10×54 Vertical Knee Mill:
- Table travel (Longitudinal X-axis): 35.5”
- Saddle travel (Y-axis): 15.5”
- Knee travel (Z-axis): 18”
- Table size: 10” x 54”
The Supra is a rugged machine tool made in the U.S.A. and backed by a one-year warranty with unlimited tech support. Check out the rest of the specs and all of the features here, then call us at 626-962-9300 or email us at sales@cncmasters.com. Better yet, contact us for an appointment and visit our facility in Irwindale, CA.
