Here is the video with the problem.
OK when you hear that rumble it IS an alignment problem.
I know you already did it but you’ll have to redo the alignment procedure. Point 2 of the Wiki is the most important (especially the part about the rod getting dead center in the bearing).
I’ve seen that you’ve put a tensioner on the long belts; it’s not necessary. On the contrary they must be a bit slack.
If I don’t have the belt tensioner then the printer vibrates very bad, jumps on the table. Without belt tensioner it was too slack, the circle was not a circle. The tensioner is not killing the belt, it’s just pulling a bit.
I will take all down today, the rods, the belt, the motors, the bearings, not the full printer, just on the top. And I will replace everything again, to see, if there is something “inside” that maybe I overlooked… I will let you know later, when the printer will be ready… again.
Cheers.
[quote=“silviur2”]the circle was not a circle[/quote]That’s usually caused by a loose motor pulley.
I am back with good news: The printer is working.
Just finished “cleaning” the top section. I took all rods out plus bearings, and cleaned them, placed bearings back, placed the rods back, I cleaned the bushings from the printer head, fresh oil, again, before placing the motor, I tried pushing the printer head with my hand on the rods/axis, and I would say is quite smooth.
Anyway, this now at this hour, it’s my second print and it didn’t skip…yet…
So, Thanks for All the help, and hope It’s gone work from now on… (cuz she’s killing me).
Hello together,
here is an additional check to run:
release all the end caps of the rods, which will move for your suspicious axis.
If you notice a smoother movement of the printhead afterwards, you are dealing with some friction from the end caps to the rods. I faced this problem a short time after building up my printer, it is a matter of tolerances.
Tighten all end caps successively and check the printhead movement until you notice a stopping force. This rod should be reviewed, maybe the end caps widened to allow a small (!) movement in rod direction.
Hello hoh61,
It’s very correct what you said, I had that problem, but not anymore, indeed, some bearings may not be placed properly and the cap could block it from free spin.
If the bearing fits nicely inside and the rods are completely in, not outside on one side, then it should spin perfectly.
Cheers.
Thank you for the information. The “Hammer” worked for me like a charme.
Now I have to fix another 100 Problems 
Hi,
in the beginning I also had a likely problem with the shifting of X or Y-axis, even after allining.
Then I reduced the ‘Trasfert speed’ to 70 mm/s and it was solved. The problem occured while ‘fast movement without printing’. Looks likes the innertial forces and friction compared to the power of the stepper motors was to high.
I also saw later that the scews of some pulleys got a little loose. Tigthening with locktide is really better.