Second/third layer not adhering

Hi,

I'm finishing my hypercube but the test prints are failing as per the video: [youtu.be]

The first layer adheres well, sometimes the second goes OK but the third have issues adhering to the second and it messes everything up.

This is an hypercube with two distinct Z axis steppers. Since the steppers are 0.8º I'm using 800 steps per unit instead of the standard 400 for the lead screw T8:

#define DEFAULT_AXIS_STEPS_PER_UNIT   { 160, 160, 800, 95 }

The bed was leveled with a UBL routine (hence the 1st layer is OK), so I don't suspect of anything related with it.


Any idea what am I doing wrong?

Any suggestion will be welcomed,

Thanks!

What are you Z lead screws?

My guess is your Z steps/mm is not correct for your hardware, so the layers are getting further and further apart

What if you do a simple Z test. Home Z, then tell it to move to Z100 and measure how far it moved in reality.

Hi,

I have two Z lead screws like these:

Machifit 400mm T8 Lead Screw 8mm Thread 2mm Pitch Lead Screw with Copper Nut

Each screw has its own stepper (and each stepper has its own driver - using the 2nd extruder slot for Z2).
I have no anti-back-lash nuts, still waiting for it.

Moving Z to 150 I can measure exactly 15cm with a rule, so it shouldn't be a matter of wrong definition of "steps per mm".

I've increased the steps per mm of the extruder from 95 to 100 and I'm doing tests.

What nozzle size and layer height are you using. layer height is recomended to be less than 70% of nozzle diameter.
What gap are you leveling the bed at and what did you put in the offset parameter in the slicer. Do your settings intend to over extrude on the 1st layer.
Its possible you are under extruding in general but an inaccuracy in the 1st layer printing/settings compensates on the 1st few layers.

The bed to nozzle gap should be less than the 1st layer height. If not its possible to compensate using the 1st layer % modifier.

Hi,

I just got tired of this inconsistent printer behavior and dismantled everything: Bed, X carriage, extruder, hotend and probe and assembled everything back again.
I also reduced the number of wires going to the X-carriage, as I had redundant conductors and I think it was too heavy because of that.

I'll be able to do some tests tomorrow night. I'll post the results here.

Thanks