RE: Wavy mystery, unacceptable quality
Wonder what the date is on these kits. The bad batch of pulleys theory sounds plausible.
RE: Wavy mystery, unacceptable quality
I just bought mine in the Black Friday special. Being on the old age pension I wasn't sure about buying a Prusa but the brand reviews have all been so positive I thought go for it. I think that was a mistake as I've been in contact with support over the linear carriage binding on the rail. I got to chat with a Bot, and it went on a meal break, go figure.
RE: Wavy mystery, unacceptable quality
I bought the Black Friday special (kit) and am not having those sorts of problems. I think very slight vertical artifacts are the nature of CoreXY systems and we get them on the Bambu printers at work too. There are two screws I'd check. Be sure the THK X-axis rail is tightened to the crossbar. The kit instructions do the final tightening at a future step and I almost missed it. It tightens like a cylinder head, back and forth from the middle. Also be sure the vertical guide rails in front (next to the top of the Z screws) are solidly clamped in the upper aluminum piece.
The case flexes slightly during printing and it's important that the CoreXY frame is tightly coupled to the bed so they vibrate as a unit. That's why having the rods (and probably everything else) tightly clamped is important.