Mucj smoother when I turn now

I would take the grinder apart and check that the 4 motor mounting bolts are tight. A number of owners have reported that theirs loosened up because the factory had forgotten to put Loktite on the bolts. A simple fix for wandering grind settings.

Is it tricky to open it to check the motor mounting bolts?

But by disassembling it I void the guarantee, right?

I can't be sure, but the top thread on the collar looks like it might be slightly damaged in the photo. The Niche threads are fine, but I don't know how anybody could have been sloppy enough to strip the threading by forcing it on cross-threaded. But just in case, take a very close look and see if the threads look precisely cut with identical sized grooves and no damaged areas. That's how they should look new and how they should continue to look. Even a tiny bit of thread damage would tend to jam the collar when it turns.

Im sorry to chime into this thread but im having a similar issue and its bothering me for some time. Im using my ZN grinder with the Gaggia Classic Pro for more than a year now. Usually I grind at around 20-22 grind setting. I clean the grinder once a month. What started happening recently is that my grind settings are very inconsistent after cleaning and calibrating. Ill Calibrate after cleaning the grinder, return to my usual setting and find that its too fine and chocking the espresso machine. I then try to recalibrate and find that the calibration was way off. Idk why there is such a huge difference between calibrations before and after I grind for the first time after cleaning the grinder.

Calibration is an imperfect process as it depends on how hard you turn the grinds setting cone. You really only need to calibrate once, ever, unless you turn the black grind level indicator ring accidentally (and can't remember by how much ), or change the burrs, it doesn't need doing ever again. If you calibrate after every cleaning, it's almost certain your grind settings will be off a bit.

A screw thread is one continuous channel, with one start...same with the top barrier....the top carrier can only ever start in the same place every time.

If you're removing the burr, then you need to ensure that the bolt is torqued to close to the same level each time. Otherwise the burr gap can be slightly different. Either a soft, wooden chopstick to hold the burrs or using a "snap" action have worked for me. Just tightening against the drag of the motor was not repeatable enough for me.

Deserven wrote:I then try to recalibrate and find that the calibration was way off. Idk why there is such a huge difference between calibrations before and after I grind for the first time after cleaning the grinder.

There is an issue with the Niche calibration that requires same method each time. And care not to shift the movable cal marker dot when adjusting.

The upper burr carrier builds up a ring in line with the mounting bolts



The ring has a bit of height and prevents the clean cal position being attained.




This causes the adjustment point to vary. Solution is to cal with the grinder spotless and then mark the clean machine point.



As long as one keeps the clean mark and the dot aligned, settings are 110% repeatable... or at least they have been for the past 2½ years.