You can use two delrin nuts pushed apart by springs on a carbon steel or Stainless trapezoidal screw to get very low backlash - at least as long as the nut doesnt wear too much (which it well eventually, probably within 6-9mo if used regualrly). The friction between delrin and steel is low enough for it to work with a reasonably strong spring, but only for small scale, clearly its not going to work for machining steel or heavy cuts in alloy. Using threaded rod instead of a proper trapezoidal screw is a false economy, unless its SS the surface finsh of a zinc plated threaded rod is very rough and high friction and no anti-backlash nut is going to work well. You are better off to buy trapezoidal, and an extra 150mm to make a tap for your delrin nut(s).