@whizzard I've just run probe reproducibility test on my delta. Test conditions:
Hot end heated to 200C, to soften any filament on the nozzle tip Probing speed 1200mm/min (i.e. 20mm/sec - this is the recommended probing speed. I also trued 2000mm/min (33.3mm/sec) and obtained similar or slightly better results. 1 dummy probe done (reading ignored) to squash any filament on the nozzle tip, followed by 10 probes, done at bed centre from a height of 3mm Each probe done twice, repeated if the difference between their stopping heights differed by more than 0.020mm (two probes was enough most of the time) The machine has x16 microstepping and 200 microsteps/mm on the towers, so the theoretical resolution is at best 0.005mm.The standard deviations were 0.018, 0.010, 0.009 and 0.015. I then repeated it at 2000mm/min (33.33mm/sec) and had deviations of 0.008, 0.004, 0.004 and 0.005. When I ran the test a little later, it had increased to about 0.015mm before reducing again.
Observations:
Filament on the end of the nozzle makes a a big difference to the deviation. I presume this is because it softens the impact, making the time of contact less precise. You can't expect better deviation than 1 microstep. Many deltas use x16 microstepping with 80 microsteps/mm, so in this case don't expect less than about 0.012mm deviation.I always heat the bed to temperature (in case it changes shape) and heat the nozzle to 200C (to soften any filament on the tip) before running auto calibration. I have the probe Z offset set to -0.050mm (i.e. it triggers when the nozzle reaches Z=-0.050mm). Then I print at 200 to 240C depending on the filament.
HTH David