My Z Axis seems to move up while printing

[LeFay Reiner]

Printer Model

2.4 300

Extruder Type

Other

Cooling Type

Stealthburner

Hello dear Voron users,
I would like to introduce myself first, I am Reiner Dobbratz from Kiebitzreihe in Germany.
As an instrument maker I use various 3D printed parts to do my job.
Jigs, pickup covers, pot knobs etc.
The 3d printing topic has become important, I can't do without it.
I hope to get help in this way to solve a problem that worries me.
I want to describe as good as possible my problem, maybe it rings a bell with you and you can give me the decisive tip.

The Z axis of my Voron 2.4 seems to move upwards during printing.
This means that when I print several objects, sometimes in "succession", the nozzle moves further and further away from the printing plate.
This goes so far that the objects printed later adhere poorly or not at all, and that the surface of the first print has larger and larger gaps between the webs, while the first print has a perfect surface. I'm talking about the surface that was facing the printing plate after printing.

I have already checked everything mechanically, all wheels are tight, belts are o.k..
Does it ring a bell with any of you? Do you know this phenomenon?
From a purely logical point of view, I think there must be step losses in the downward movement of the Z axle.

I would be very happy about a tip because I am very concerned about this matter, and because I can't get any further without help.

Best regards to the Voron community,
Reiner

 

[Dre78]

Huum going to have to give little more info on ur setup bud ( slicer , z hop setting, fresh build, or ran fine for hours and now not working? Z move free all the way up and down .

 

[LeFay Reiner]

Thank you for your interest in my problem, at the moment I am doing a test run and gathering more information. More later. thank you

 

[NoGuru]

I would think the rotational distance is wrong or you have the wrong gear installed.

 

[Dre78]

The part when he said print in succession to me is using simple3d and rotation distance would effect all the piece or I’m I missing something ?

 

[ComradeXavier]

increasing effective Z height during a print might be due to thermal expansion of the frame. I have observed that on my 350mm V2.4 when printing a full plate of small ABS parts. ABS temperatures and enclosure yields more thermal expansion; many small parts yield long layer times. My first layer is usually especially slow and so it is affected the most. I have mitigated the problem by ensuring my layer times are short enough to amortize the expansion over many layers.

Klipper's z_thermal_adjust should solve the problem, but it requires a frame temperature sensor and calibration. I have a frame temperature thermistor installed, but other projects have kept me from calibrating the expansion coefficient. So, I cannot comment on how well it works.