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
It’s extremely expensive to produce things with tight tolerances. Cheap 3D printers have gotten away with it by making things “good enough”. Which why you got this the other way around;
0.3mm is easy to measure with the right tool like digital indicator. On the other hand, quarter turn on a knob might adjust 0.3mm on one bolt, but 0.5mm on another.
Also as mentioned, ABL, cheap and can be DIYed. Cheap / printed parts can warped over time, bolts can shaken loose, etc. ABL just put these out of the equation.
How much do you need to turn the knob for 0.3mm? Most people don’t know the answer so they make a guess which is likley wrong.
If the firmware converts 0.3mm to 1/2 rotation it is clear what they should do. This particular printer probs itself after the adjustments and if it isn’t right it shows once more the dialog/instruction with the adjusted rotation value. After 2 rounds, you would already have accounted for the manufacturing tolerances.
This process can be ontop of ABL and z-offset dialog (eyeball it with a shim, testprint, tell the printer which looked the best, the firmware knows what z-offset was each of the 5 prints/lines).
I largely agree with what you’re saying, but was surprised to see that you called out that much variation in thread pitch. I would absolutely expect a lot of variation in the ability to measure z - especially since most printers rely on microstepping here. Thread pitch on the other hand is generally way more consistent. I am not a machinist, but it would be interesting if one chimes in. I don’t know what to ask Google to get some data here, but I strongly suspect there’s a term to use.
Even in millimeters, there’s a wide range in standard thread pitches. 1mm thread pitch in most common screw sizes is generally available, sure, but don’t always fit the “cheapest sufficient part” criteria.
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.
Tight tolerances will exponentially skyrocket production cost, period.