Hi folks,
I seem to observe that when I do “live” adjustment of the Z offset during the print it does not honor negative values. Positive work, but if I go below zero on the touchscreen, the nozzle stays at 0 offet. The touchscreen shows the neg value, but the expected effect, plastic pressed down stronger is not there. If I go to insane values that usually would basically rub the nozzle into the printing bed, still no effect. It may be connected to me doing a manual 11x11 calibration now - anyone else observed something like that?
Oh, btw. on newest firmware, i.e. 1.13.2 if I’m not completely wrong…
Annoying…
Cheers
Hauke
@Hauke i wonder how it is that Snapmaker always manages to successfully screw up the firmware. Every other printer on the market has a negative as the norm.
Check that your sensor is still adjusted properly and hasn’t slipped down?
Also double check that you’ve mounted the head in the right holes so it isn’t lower than it should be.
You aren’t using any type of additional bed (glass, quick change?) that’s changing it to where it isn’t where it thinks it should be?
-S
…and SM2 had it too. I’ve in the past been using negative offsets successfully. I can only imagine two reasons: Firmware bug in the most recent firmware, or some subtle problem arising from me not using the standard calibration via touchscreen, but the 11x11 via GCode “injection”. Since I’m currently mid-print, I cannot test if neg-Z works with standard calibration.
Sensor is just fine, head mount as it should be, stock print bed and print sheet - everything pretty standard 
There is a strange and annoying bug with z-offsets that screw things up. There are a couple of other threads about it. It was introduced when they changed firmware to write the offsets to EPROM (to allow for correctly applying them when recovering from a power failure). However, in some instances it is now ignoring the z-offset (or applying it twice) making the whole thing out of sync. I’ve noticed that it behaves differently, depending on whether you change the offset during printing or prior (through the adjust button). But I haven’t figured out what exactly happens and in which instance, to be able to avoid the issue.
Calibration does not fix it unless you first manage to set the z-offset to 0, then power cycle and then calibrate. The guy who found this workaround has also reported the bug way back in September…
On my machine I can do negative offsets, but at one point my machine was printing high in the air and the negative correction reached its limit. Last time I printed the first print started fine (no adjustments needed), then the next print unexpectedly dug deep and destroyed the print sheet. Now I’m waiting for my replacement order to arrive. I don’t know what caused the latest surprise so I’m not sure what to do when I get it, unless someone can confirm if it is safe to downgrade the firmware (and the correct steps for doing it). I’m on the latest fw as well, with all the tools upgraded too.
Gosh, that’s so annoying… Why don’t they just stay with well-proven Marlin code? It seems that they re-code too much stuff…
@Hauke because them screwing things up keeps the forum active since they don’t care to come here themselves anymore 
Look at this latest pull request, the absolute chaos of commits not rolled into one. They have no idea what they are doing 
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