Bridgeport CNC Retrofit

Our Bridgeport Series I Boss 7 CNC Mill came with the original control system, along with the infamous automatic tool changer (this has been regarded as one of the worst CNC tool changers ever made). The machine was in great condition mechanically, but having the original control system means it had servo motors driven by quite old electronics. It was the perfect candidate for a retrofit to newer, upgraded controls.

The first steps we took were in an effort to reduce size. In any shop, you can never seem to have enough space, and Motim is no exception to that rule. The tool changer had a very complex pneumatic and electronic control system, and the enclosure for all those controls was enormous. Research pointed out that the Boss 7’s tool changer controls were unreliable at best, and at worst, the tool changer would occasionally throw a tool holder up to 30 feet. As such, we decided to forgo the use of the tool changer in favor of changing tools manually. Removing the tool changer and its control enclosure cut the footprint of our mill in half.

On to the important part, our upgraded controls. We chose to use 2000W servo drives with 2048 count encoders. They supply plenty of power, and give us about 0.00005 inch resolution. For the spindle, we kept the original motor, and powered it with a 3 HP GS2 variable frequency drive. It is all currently being controlled with Linux CNC.

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