I'm building another machine and will use Acme with zero backlash nuts. My K2 machine had Nook standard ballscrew, the ball nut had 0.007 backlash (which was within their standards) and 0.005 to 0.007 in 12" on the screw (also within standards). These standard ballscrews are not sold as suitable for cnc use, and they are not, they are motion grade ballscrews. My standard grade, super cheap Enco acme with zero backlash nuts give me less than 0.005 in 12" for 5% of the cost of the precision ballnut/ballscrew assembly from Nook anyway. IMHO
A single ballnut can have very low backlash, but either you or the factory is going to match the ball bearings to achieve it at a much greater cost than a simple acme zero backlash nut (ie dumpster sells these nuts for like $19.00). Nook wants $100 to load a single ballnut, $175 will buy a double ballnut for zero backlash. |