Bridgeports with ball screws? How to tell?

[bogiestl]

I'm probably going to convert a benchtop mill, but if I end up where I have a garage after I get moved, I'd like to pick up a Bridgeport for the larger non-CNC jobs... But I'd eventually like to convert it too... I'm going to be making predominantly smaller parts for a niche market or two, but having a big mill would just be convenient...

If I don't have to replace ball screws, stuff would be significantly more simplified. Eventual CNC conversion will likely involve a fourth axis running off a Mach3 controller, since I've seen how difficult things get in keeping older machinery/controller electronics running.

Any hints/pointers? I use a Jet 9x42 and a BP 9x42 daily for manual stuff...

[frijoli]

"If I don't have to replace ball screws, stuff would be significantly more simplified."

You most likely will not find a manual mill with ball screws. However they are easy to spot if you actually look at the screw. Standard screws use acme threads, and ball screws have rounded grooved thread for the balls to engage in.

They feel WAY different when you turn the handle too.

Clay