CRITICAL: Missing Z-hop movements during printing are causing print failures and nozzle dragging.

[amzaldua]

Bambu Studio Version

1.8.4.51

Where is the application from?

Bambu Lab Official website

OS version

macOS Sonoma 14.2.1

Additional system information

Apple M1 Macbook

Printer

Bambu Lab A1 series

How to reproduce

Printing a G-code generated with Bambu Studio with a non planar superior surface.
I attached an example.

Actual results

The nozzle scratch over piece.
Check the movement between 43684 and 43685, there is no a Z-hop movements.

Expected results

The nozzle should be retract in Z axis between movements in the same layer and in the same type of line. Always.

Project file & Debug log uploads

debug_Fri_Jan_19_08_40_03_43376.log.0.zip
scratching example.3mf.zip

Checklist of files to include

• Log file
• Project file

[amzaldua]

The 3D printer and the nozzle are straining, which could lead to damage to the machine. Please, fix this as soon as possible.
The machine firmware is the 01.01.01.00
You can refer to https://forum.bambulab.com/t/a1-and-bambu-studio-issues-z-retractions-and-axis-limits/48872 for more details.
I have a ticket created with the number US240112563001 since 2024/01/12 without any response.

[tsmith35]

I think I understand the issue related to the nozzle scratching. It seems that the slicer doesn’t generate retractions when it moves rapidly within the same type of line. In other words, if the nozzle quickly moves from one XY point to another XY point, at the maximum feed rate, and both points belong to the same type of line, the slicer doesn’t retract in the Z-axis, even if the trajectory passes through lines already deposited in the same layer.

@amzaldua I saw your post and have observed the same thing. It is quite fortunate that you have "extensive knowledge of G codes and the kinematics of complex 5-axis machines" as you stated in the forum. The overwhelming majority of users would not have been able to debug as effectively at the gcode level.

Have you already added an issue for OrcaSlicer as well? Thanks.

[amzaldua]

No, I haven't done it yet, but since you suggest it, I will do it to help OrcaSlicer users. Thank you.

[amzaldua]

@tsmith35 The link to OrcaSlicer issue

[tsmith35]

@tsmith35 The link to OrcaSlicer issue

Awesome. Thank you!

[Loriborn]

Wanted to add that I've experienced this problem as well. Relatively flat prints with a lot of infill experience this the worst, and the issue seems to be exacerbated with smaller layer heights. 0.24mm seems to avoid the problem, probably due to more generous tolerances, but 0.08mm always results in the nozzle scraping over infill, regardless of the type of infill.

[XunZhangBambu]

@amzaldua Hello, personally ,this place doesn't require a Z-hop. Z-hop only occurs during retraction and layer change. And after printing, I haven't encountered a print failure. Could you please tell me why a z-hop is needed here?

[tsmith35]

@amzaldua Hello, personally ,this place doesn't require a Z-hop. Z-hop only occurs during retraction and layer change. And after printing, I haven't encountered a print failure. Could you please tell me why a z-hop is needed here?

@XunZhangBambu is it possible for users to enable a Z-hop before crossing infill? While I agree that it's not needed under ideal conditions, it's possible to drag across infill if the infill is overextruded or if the print suffers from slight warping upward.

The condition of the nozzle dragging across infill is so commonly observed that there is a nearly universal admonition on numerous Bambu-related forums to avoid grid infill whenever possible. This is troublesome for two reasons: (1) grid infill is the default infill in Studio and (2) Prusa users (and users of other printers) typically don't experience the issue. While I appreciate that skipping the Z-hop does speed up printing, it has resulted in a widespread recommendation to use gyroid infill to obtain quieter prints and avoid potential hotend damage. As you know, gyroid infill is one of the slowest infill styles available, but many users use it to avoid the grinding/scraping noise that occurs so often when using grid infill with no Z-hop over the infill.

The minimal speed gain obtained by eliminating Z-hop for increased speed across infill is a disservice to Bambu Lab's many users. That slight speed gain is strongly offset by the many, many users complaining about "loud" infill, reports of scraping noises and users thinking that their printers are being damaged by "dragging across infill" when they use traditional infill styles such as the default grid.

I can't imagine that this is the desired user experience for Bambu Lab printer users, but it's what I've observed as a regular user complaint. As I often point out, every user's experience is different and is strongly dependent on the user's skill level and environment. I'm sure you have many, many hours of experience with 3D printers, but that's not typically the case for most Bambu Lab printer users (or users of many other brands, for that matter).

[SaltWei]

is it possible for users to enable a Z-hop before crossing infill?

Disable this setting.

Modify this setting as your need