Here we get easily -20 degrees celsius in the winter, so drains are quite a steep angle, and I doubt there.s any water in there. I could solder a cap on the copper pipe and fill it with water. The issue is that I can drive it very deep outside the workshop, but the upper 20-30 cm of the water filled pipe will freeze along with the ground, and probably crack, so goodbye water, and the second option is to drive it beneath my workshop where I have a rudimentary form of what you call a cellar in the Uk, and it.s freeze proof, but I doubt I.ll manage to drive it more than 50 cm, as beneath 2 meters, the soils become quite rocky.

Now about the g code, putting g1 x100 f300 into mdi, moves the axis 50 cm.
All ballscrews are 5mm pitch, and the toothed pulleys on the Z are at a ratio of 2:1, 20 teeth for the stepper and 40 for the screw, so I.m sure I.ll have to mention this somewhere in mach3.
Although the steppers do not make a uniform sound all the time and have small hickups now and then, running the x axis 20 cm to the right, and then returning it to where is was, measured with a dial indicator, is dead accurate.

Rob mentioned an earth spike. I can find locally steel and zinc ones, and copper coated just online. I don.t mind buying a spike, it.s just that I already have some copper pipe.