Inconsistent layer shift- at my wits end

  • I am having an insane issue with layer shift with my Ender 3 v2. It seems to only happen when I have multiple models on the plate. For example, if I print a single cookie cutter for my kid's play-doh, it comes out pretty much perfect. If I print a batch of 4, that’s when we see layer shift. I can also demonstrate this with the XYZ cube. One cube print comes out perfect, but if I do four, they are all messed up. The layer shift is also random in nature. If I print the same batch of items from the same gcode, the layer shift will be a different pattern. I am using regular PLA (inland and overture) I have gone through all the standard Calibrations and in the beginning, things seemed to be fine. The printer sits in the basement, and its difficult to babysit. on occasion, I can hear a quick "pop" from the printer, one that sounds like missed a step, but it’s basically impossible to tell which axis it came from.

    I am using Cura 4.8.0 "canned" standard quality profile

    • Retraction distance 5.4
    • Retraction speed 45
    • Flow 95
    • Print speed 50
    • Wall speed 25
    • Initial layer speed 20
    • hot end 200-210 depending on the exact brand style The Black I have in the example is 210
      60 bed

    Firmware is Creality 1.0.2

    Things I have done:

    • Estep calibration- Done, set to 97.1
    • Flow calibration- Done, for inland filament seems like 95 works well.
    • Retraction calibration - my tests show 5.4/45 has very good results.
    • Completely torn apart and realigned the Z axis. I needed to add a washer on the back of the Z axis motor in order to get it to align with the brass nut on the extruder mount. Screws are barely snug on the z axis motor, otherwise the motor wants to kick out and tilt the lead screw out of alignment. The brass nut screws are backed off a bit in order to give it a tiny bit of play. I checked the leadscrew itself, and it is true. Everything slides nice and smooth with little effort
    • Adjusted the X axis eccentric nuts. I made sure it was loose, then tightened it up such that there is no wobble and none of the wheels free spin. At first, I had this way too tight, everything slides nice and smooth now with little effort
    • I didn’t do too much with the Y axis. The eccentric nuts were loose from the factory. I tightened them up just enough that there is no wiggle in the bed. It always slid nice and smooth with ease.
    • Belts- obviously checked this one hundred thousand times. They are tight, but not stupid tight. They do not appear to be rubbing on anything obvious.
    • I made sure the idler pullies were screwed in tight. The pullies on the motors are pressed fit.
    • Bed is as level as its going to get. I had to throw a few slices of aluminum foil in the middle because its slightly sunken in. I've had few issues with bed adhesion, except for this black which appears to be persnickety. the layer shift happens with any PLA I have tried though even when adhesion has been perfect.
    • Heat- I thought the motherboard might be overheating, I cracked open its enclosure to allow the fan to blow in, and heat to escape from the top.
    • VREF voltages- I thought maybe something was incorrectly calibrated from the factory so I checked the VREF voltages. Everything looks good per marlin's spec, even on the high side of their rage. 3 V2/#vref. I also checked the electrical connections and they seem tight.
    • Motor temperatures- Not sure what they normally run at, but with my heat gun I can see Z is 53c, X is 31c and Y is 47c. None of those seem unreasonable.

    At this point, I have no idea what the issue could be. Knowing my luck, I overlooked something stupid obvious, or I legit have a defective motherboard or motor. I should also mention that I was having the layer shift issue way worse before I adjusted the Z and X gantry. Before I got those dialed in, a single large model would experience layer shift. I seemed to have got past that. Note the pictures of the white frying pan, before and after adjustments. Also I have pictures of a set of four cubes that I just did (don’t mind the warping, that’s not generally an issue, this black PLA I don’t have dialed in yet, I don’t have that issue with anything else I have done) The single cube is one I did all by itself and you can see its pretty much perfect. Any help would be appreciated.

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