Having issues with first benchy (and 2nd, 3rd, 4th...)  

Having issues with first benchy (and 2nd, 3rd, 4th...)

I received an MK4, fully built. Removed from packaging (the shipper had delivered it on its back, not sure if it was upright through the rest of the shipping experience though. I righted the box, extracted the printer, and ran through the setup process by the book. It all went smoothly. Loaded up the Galaxy PLA that was included with the printer, and ran the benchy test print:

Comparing this to my other first benchies from an Ender 3 S1 and Bambu P1S, there are some obvious issues—most notably, around any transition from fill to surface, there was a noticeable layer shift, like 1-1.5mm! I posted this to Twitter, and got some helpful responses, a few people said to use the Prusa Belt Tuner web app.

I did that, and switched filaments to Prusament's Prusa Orange, and here's the result, with the same file:

I had loosened the Y-axis belt a little, as the app was saying it was too tight (like 120 Hz or so), so I loosened it underneath until it was in the green range and the app said 'just right' (and yes, I was plucking just the top of the belt, not touching both belts, etc.). I had printed that at the same time as my Bambu P1S was printing alongside it, so I wondered if maybe the table's shaking could've caused the issues to get worse.

So this morning, after taking a few more Twitter suggestions into account, I ran another print without the Bambu running, just to get a baseline and make sure table vibration from another printer wasn't an issue (a lot of people told me it shouldn't be... but I like being sure). Here's that print:

I also physically pushed around on the hot end (when it was not hot), the print head/extruder, and the y-axis bed, and all are solid, with no wobble (okay scientifically speaking maybe like 0.01mm since nothing is perfect), but they are very solid, no wobbling or anything.

I also sliced my own benchy and am running two test prints now, one with input shaping, the other without, just to get baselines there.

Are there any other things I should check on, or should I re-check the belt tightness again? A lot of people seemed to think that could be the problem. I wish there were a more scientific way to check belt tensioning than plucking the belts with the app...