I have a 1965 Series I Bridgeport 9X42 Mill that I have converted to 2 axis CNC. I am presently using the old Acme leadscrews, which have about 10-12 mills of backlash near the center of travel. I have split the nuts, and tried all sorts of adjustments, but the wear especially on the X-axis results in too much drag away from the center of travel if I tighten the nut further. I have a 2 axis DRO on the machine.
I am contemplating converting to ballscrews to reduce backlash and increase motor efficiency. I can deal with metric conversion in software, so I have been looking at some rolled ballscrews on e-bay, from a chinese company; the store name is linearmotionbearings. I know several people have used their products in homemade CNC applications and seem fairly happy with the products.
I solicit comments on my idea to see if perhaps I am missing something. Has anyone tried this, and compared it to the Rockford conversion kits? Another question is whether I need to use 30 mm diameter ballscrews or if I could downsize to 25 mm ballscrews. My machining does not require heavy cuts, so I am tempted to use the smaller screws. Another question is if I really need left hand threads on the Y-axis screw. I can deal with the direction reversal in software easily. I can also compensate for linear errors within reason. I do not feel the need for higher precision from ground ballscrews.
I do not want to spend too much money on this project since the mill is used for hobby work, and I am retired on a fixed income.