so what causes this?

[printbus]

Rigidity: motion in the x axis is resisted by the primary square frame of composite wood in plane, which is super stiff in that direction. In effect the stops and starts have something firm to push against. In the Y direction the stops and starts are resisted by a very small piece of wood in the bendy direction especially at the front piece where the y idler attaches, hence more oscillation/ringing.

If I'm right ringing might be reduced a good bit by stiffening that y idler mounting piece. I need to test that. I bet it's less of an issue with the original linear bearing I3 version because that piece was doubled up in that design. Anyone who had both care to comment? or are there too many other variables to compare? From what I've read acceleration/jerk/move planning is a bigger factor, though.

I also read somewhere that the more the machine is allowed to move overall during printing the less this happens. An argument for rubber feet.

I think we're miscommunicating. In my case the ringing is observed on the print sides parallel to the Y-axis. In other words, the print sides that go from Y+ to Y-. Since the ringing is observed on that axis, the ringing has to be lateral movement on the X-axis. Right? Or maybe not... I guess I can kind of see that if the nozzle is moving in the Y direction and the frame is also ringing inline with the Y-axis, the net effect would be the nozzle accelerating and decelerating with respect to the print, and that could cause an artifact to show up. TJC, is that your theory? Interesting possibility I'll have to ponder.

I long ago added 1/2-inch wood reinforcement plates to both Y end plates. The 10 and 12 inch printers likely need something like that even more. As of my last maintenance cycle, I've got the belts tighter than ever or I'd focus on that. I've got the Sorbothane feet installed.

I picked a bad day to do some power rewiring. Might have to kluge things back together to get some test prints underway...