That does look better around the star at the brim. Are the lines in the middle of the star just drooling / stringing from leakage during moves or was that supposed to be infill?
If you’ve had to adjust all the way to -0.5mm using offset, you’re not calibrating as tightly as you should, for sure.
So there’s 2 steps as I think @xchrisd already implied. First is you should be able to find a help / FAQ on positioning the sensor to the right height on the print head. (Sorry, I’m being lazy not looking for the link myself to put here…it is Xmas eve after all.) Remember the calibration procedure at first is using the induction sensor to make a ‘map grid’ of bed distortion but not by the sensor or nozzle ‘touching’ an actual zero height … it’s supposed to trigger at an offset. The last step of that calibration procedure is where you use the nozzle to determine the final delta to apply to that distortion map.
Second when you do the calibration - 4 x 4 or 5 x 5 steps or whatever, I strongly recommend warming the bed first. Have your print plate on it, use the manual controls to heat the bed up to your usual bed temp or a few degrees above (say 60-65C) and let it hang a few min. I used to think heating the print head too mattered but not so much anymore, and in any event leaving the print head at print temps a long time without printing is slowly burning what’s in it and leads to clogs. So – heat the bed, which lets it build in whatever natural curvature / distortion it might want to, THEN initiate the bed mapping.
At the end of the bed mapping when the print head moves to center and waits for you, you want to use your calibration card paper under the nozzle. If it starts at the 0.5mm increment I’d recommend only bumping down ONCE at most to save button presses – then move to 0.1mm. Bump down, test paper slip, bump again until the paper is feeling the friction but still sliding. The move to the 0.05mm setting. Bump carefully once and test again. You want the paper to be able to be pulled with significant resistance, but not be able to ‘slide back’ without just humping up instead. That’s your starting default. Hit the button to confirm your finished cal. The key with all this is you don’t want to ‘overdo’ it and bury the nozzle / make it too tight then ‘back off’ … it’ll actually not cal as well if you have to do that. (If you do find you hit ‘too tight’ and paper is absolutely pinned, best off to just back off, confirm to end, and start over from a new home and reheating the bed.)
Also – the cleanliness of your nozzle obviously matters for this step, especially if cold. You can imagine how a bleb on the nozzle could add to more paper compression early vs. the metal itself.
For silkies you may STILL need to offset another 0.05mm down (or two!) to get a good squish and stick, while normal PLA might be ok there already. I used to be utterly paranoid about calibration for every single time I removed/replaced a print plate. Now…I only really re-calibrate if I have swapped tool heads to laser for a while, then swapped back so it makes me. (I don’t even recalibrate for different print plates anymore [of same, Snapmaker origin] … Just watch that first line go down on the skirt and then update the Z-offset a step up or down if I think it needs it…although I did just buy an off-brand spring plate with some different textured PEI / PEO and will probably recalibrate when I try it out because it’s a totally different manufacture.)
I’m also wondering if you ever did the extruder stepping calibration up front, and/or if a later firmware update replaced that calibration on you? There’s a giant thread on that (and a newer ‘digest’ thread that pulled out the high points.
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