Building a 3D printer is easy. Getting the details right to build a great 3D printer is hard, as this is where most companies fail. Why?
For example, on this printer, the bed is a three-point mount (two wheels for adjustment at the front of the printbed) and the printer’s bed levelling dialogue doesn’t show the height difference that needs to be adjusted (which most 3D printers do). It does show how much it needs to be turned, and the bed levelling wheels have 1/8th turn indicators, making it easy to get it perfect.
In short, instead of an arbitrary number like 0.3mm that has no meaning to the user, they tell the user to turn this knob 1/4 of a turn. An instruction the user can follow.
** Why is this so outstanding? It doesn’t cost much, but it improves the user experience. Are companies blind to these improvements because the engineers are experienced, or is there a lack of testing during development?**
By the way, years ago I did such a fix/modification myself on a Tronxy XY2 pro by adding indicators on the wheel for 0.2mm height difference so I could convert the number to rotation: https://www.printables.com/model/301670-replacement-bed-leveling-wheel
Screws of the same pitch will generally be pretty consistent regarding their specified pitch. Unless the manufacturer is randomly grabbing screws, and their matching nuts, from a mixed bin there shouldn’t be much variation.
I didn’t say anything about variation between two screws of the same pitch. There are various pitches for each length/diameter of screw on the market, and some are more common than others.
But this is what everyone else is talking about, because that’s what matters in this case. The manufacturer knows exactly what type of thread they used, and the variances within that type are really small, so they can easily tell how many mm of vertical movement 1/8 of a turn is with high consistency.