The dreaded..........."Backlash"

[irving2008]

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).

[pjl83]

I've only ever considered stainless rod. I'll have to have a play with it and see what I think. I've seen lots of home build's around the net that use threaded bar with good enough results for what I'll be looking for. Although I agree that there is a little bit of false economy in going this way, but if the funds aren't there then I'd rather get it going on threaded bar and see how we go than waiting until I can afford the better options.

The construction will be easy to disassemble and modify in the future.

Thanks again
Paul