I bought a Vellemann K8400 a few months ago. I’ve had some issues with shifting layers. I’ve followed all the guidelines and troubleshooting tips on your website. I’ve also used all tips that I’ve come across by googling. The issue is that the movement of the print head on the x and y-axis is not smooth. I’ve even printed alignment guides for the rods to ensure alignment between the X and Y axis. I have a digital caliper as well to double check. The issue seem to be clearly linked to the rods, it is very difficult to get a perfect alignment. I’ve redone the alignment like 3-4 times, but it doesn’t run smoothly still. With enough lubricant on the rods the printer prints well for a short time, so it works for smaller prints. However if I print parts that take more than 2-3 hours I get shifting layers. When testing manually, it is clearly more resistance moving the print head towards the edges of the printer. Especially towards the back end. I’ve tried to adjust to make is move smooth, but without luck so far. Can the rods themselves be off?
I’ve now spent so many hours trying to fix this issue, and I’m out if ideas. I hope you can help