Printer missing steps, is the rods bent?

Vertex 3D Printer Vertex - Assembly and user manual
1

After first assembling my kit i had problem with the K8400 missing steps causing the prints to go bad after a few layers.
Accepting the the first defeat i ended up reading alot about how to properly [color=#40BF40]align the xy-carriage[/color].

After reassembling the xy-carriage and then enlarging the distance between the clamps i got the printerhead to move with almost no friction,
as long as i are moving the opposite side of the rods(at the clamps) equally. Moving one of them to much/little so that the rod no longer is
perpendicular will increase the friction a lot so that the the rod have to be readjusted to become more perpendicular to allow further move.
Is this normal or have i enlarged the distance between the clamps to much? I felt that friction when moving the rods was to high before
enlarging the gap this much.

After attaching the belts and adjusting the rods to be as perpendicular as possible with only a digital calliper (about 0.1 mm difference).
I then moved the printerhead by hand, and both in x and y axis i feel that the friction increasing about once ever 100mm, after that distance
it become easier to move again, and then again after about 100mm the friction increase again. Turning on the power and stepping movement
from the controller show the same behavior that some areas have more friction that others. The friction as about the same in the middle as
towards the end of the rods, its just some parts during the movement the friction increases.

Another thing i noticed will trying to troubleshoot the printer lately is that when i move the printer head in x or y axis i can see that the clamps
are moving up and down very slightly just like if the rods are a little bent. Is this normal? or could it be that the rods Velleman delivered
was slightly bent causing me all this trouble?

2

It’s always hard to tell where the problem is lying. If the alignment is not fit the rods will bend when moving the head.
So it’s important to test such things before the assembly : rolling the rods on a flat surface, check if the diameter is constant, check the length.

3

I have taken apart the printer and measured the rods now, the result is below.

350mm Ø8mm ROD

  • Measured lenght: 350mm, and Ø7.95mm. The diamter is constant.
    289mm Ø8mm ROD
  • Measured lenght: 289mm, and Ø7.96mm. The diamter is constant.
    298mm Ø8mm ROD
  • Measured lenght: 298mm, and Ø7.96mm. The diamter is constant.

I guess the diff of 0.05mm in the diameter is within the tolerance?

Checking if the rods was straight was more difficult, rolling the rods on a flat surface i could not notice that the rods was bent. I then attached the rods to two clamps(as the 350mm rods are “attached” in the printer) and rolled the rods, i could then notice that 3 of the 350mm rods and the 298mm rod was slightly bent. Difficult to say how much they where bent since i only had my eyes to measure with, but i think the rod was moving up and down with about 1 mm in the middle while rolling them. The 4th 350mm and the 289mm rod I could not visually see that they where bent.

Based on my measurements, does it sound reasonable that my issues are from such small bend in the rods, or could this be something complete unrelated?

4

I discussed the issue with Velleman and they will send me new rods.