Ringing Part 1: Tightening the belts
Ringing problem still persists.
The consensus among 3DP operators is that ringing is caused by loose belts and too-high acceleration and jerk values. In entry #1 I found that changing accel/jerk didn’t do much, so let’s try belts.
Wanhao distributes its belts with tension springs to hold them taut, but of course the spring introduces springiness (haha) and that is not great. So I removed the springs and then tensioned them myself. The X belt was tensioned using a screw tensioner (can’t remember the Thing I used, sorry!). There wasn’t enough room for a tensioner on the Y belt, so I cinched the belt tighter with zip-ties.
The end result was that ringing was greatly reduced, but not eliminated.
BUT BAD THINGS HAPPENED TOO! Tightening the X belt put a lot of tension on the towers they were mounted to, and this caused the Z axis to rise at different rates on each side, leading to the printer locking up once it rose high enough. Similarly, over-tensioning the Y belt visibly pulled on the idler, which is only supported on one side like a cantilever.
Ultimately, I removed the screw tensioner from X and re-tensioned both belts manually. I did this by getting the length of belt that would firmly fit around the mounting screws, and then tying it off short by 2 teeth.