That degree of accuracy is quite expensive, costing thousands of dollars per screw, and only attainable in ball screws which have been finished with precision grinding.
In general, it is recommended that industrial lathes should be C3-C5, which means zero backlash, and accuracy of about 0.001mm. The bigger the number, the less accurate the screw. However, the cross slide is machining in both directions, in and out, so the absence of backlash is necessary to maintain workpiece accuracy.īallscrews have grades of accuracy varying from C0 -C20. Interestingly, it is less important on the CNC lathe lead screw, because most CNC lathe machining on the leadscrew occurs in one direction only, towards the headstock.
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Another name for ballscrews is “antibacklash screws”.īacklash is annoying on a manual lathe, but it is very important on the cross slide of a CNC lathe. They used to be many times more expensive than the older types, but since China/Taiwan has taken over most of the manufacturing, often using equipment sourced from US/Europe/Japan, the costs have plummeted.Īnd the backlash is minimal or zero. They are generally more accurate than square or Acme threads. If they are noisy there is something wrong. Even Wabeco, the respected German lathe manufacturer no longer specifies any threads except ball screws.īall screws require less power to turn due to friction being a fraction of the alternatives. The alternative is Acme or square thread screws, but the few manufacturers who used to use these have all switched to ball screws (as far as I know). )īall screws are the usual positioning screws for CNC machines these days. (can something be “very” crucial? It looks a bit like “very unique”. For those relatives and friends who follow this post, who have no idea what I am talking about, the “ballscrews” are what determines where the cutting tool on the lathe is positioned. And I have purchased 2 ball screws and nuts on Ebay. I have learnt a lot about ball screws in the past few days.
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