Before I had a serious accident with a mouse that resulted in a 3.5 tonne Shizuoka mill turning up at the house, I converted my Bridgeport clone to CNC using a Chinese all-in-one controller from Newker. Those things in the photos are for the z axis drive, housing the closed loop stepper, timing belt drive and pulleys. I fitted a 16mm ballscrew where the original feed trip adjuster screw used to live, as this is much neater and robust than the usual arrangement with a ballscrew cantilevered in front of the head and required minimal modifications to the head. The top one is the final iteration.
Here's a picture of the basic mechanism, before the limit switches, encoder scale etc were fitted (otherwise you wouldn't see the ballscrew).
You inevitably lose some of the precious z axis travel due to the limit switches etc but I managed to minimise that and retain most of the 5" motion.
