Need some help with y-axis shifting and stepper chattering please

[CoolHandMike 0]

Trying to troubleshoot why my Y-axis stepper goes into berserk mode all of a sudden. It's very reproducible with this print after about 25 minutes: https://www.thingiverse.com/thing:275...

 

Video of the fault (after a few infill passes; skip to 2:35): 

 

 

Things I've tried, to no avail:

• Reduced the Y acceleration from 5000 to 2500 to 1000
• Adjusted the trim pot on the driver both ways in 1/8th increments
• Changed the infill from cuboid to grid
• Reduced print speed from 60 to 40
• Ensured belt is tight and not slipping
• Replaced Y-axis stepper with a new one. Already noticed it is operating much cooler and quieter (original stepper would hit mid 40's C during normal printing whereas all my other ones rarely hit 25°C. Still failed the print at about the same time. 😠
• Reduced print size to 75% (I noticed that the walls have just a tiny width of infill(?), and when the printer hits this layer, the back-and-forth is shaking the whole machine. I thought reducing the print size would eliminate this "wall infill" but it only did slightly. Print went much farther before the dreaded Y-axis shift appeared. Maybe 30 minutes.)
• Reduced infill speed from 60 to 30 mm/s on the 75% print size. This one went 45 minutes before it failed with a Y-axis layer shift. That's where I called it quits for the night.

 

I have many other successful prints but this one is driving me insane. TIA~

Setup: Anet A6 frame and steppers with KFB3.0 motherboard and Marlin 2.0, Cura 4.4 slicer set to draft

 

Edit: Just tried the same print with Prusa Slicer and default settings and it printed perfectly. So now I need to figure out what settings in Cura are causing this. Any ideas?

 

Edited January 1, 2020 by CoolHandMike
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