CRITICAL ISSUE: Missing Z hop: Nozzle Collision Issues During Movements

[amzaldua]

OrcaSlicer Version

1.9.0

OS version

Mac OS Sonoma 14.2.1

Additional system information

Apple M1 Macbook

Printer

Bambu Lab A1

How to reproduce

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

Actual results

The nozzle scratch over piece.
Check the movement in layer 142 between 59672 and 59674 lines, 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

issue nozzle dragging.3mf.zip
Archivo.zip

Checklist of files to include

• Log file
• Project file

[amzaldua]

Please, check this as soon as possible. I came from BambuStudio because of the same issue, and to my surprise, your software has exactly the same problem. This issue damages our nozzle and ruins our projects because the piece is scratching and detaching from the bed. Bambu Support is missing.

[CCS86]

It's called Z-hop. Retraction is an extruder move in the negative direction.

[amzaldua]

It's called Z-hop. Retraction is an extruder move in the negative direction.

Updated. In the context of CNC machining, it is accurate to use the term "Z retractions," but I acknowledge that in the world of 3D printing, it might lead to misunderstandings. Thank you for the correction.

[tsmith35]

@amzaldua you left out the forum link with the expanded description. I will attach the link at the bottom.

Here is my comment from the same issue in Bambu Studio:

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 {hop} in the Z-axis, even if the trajectory passes through lines already deposited in the same layer.

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.

https://forum.bambulab.com/t/a1-and-bambu-studio-issues-z-retractions-and-axis-limits/48872

[amzaldua]

You are right. Thank you!

[Loriborn]

I wanted to verify that I am experiencing this issue with OrcaSlicer as well, after trying it out due to this issue while using Bambu Studio.

[ReinhardC]

Try removing the checkmark on Process settings>Others>reduce infill retractions. This helped me get rid of some nasty infill collisions.

[amzaldua]

Try removing the checkmark on Process settings>Others>reduce infill retractions. This helped me get rid of some nasty infill collisions.

Thank you. I'm going to test this option. It shows promise.

[Loriborn]

Try removing the checkmark on Process settings>Others>reduce infill retractions. This helped me get rid of some nasty infill collisions.

Thank you. I'm going to test this option. It shows promise.

I have tried using this setting, and still experience the issue.

[Snelso91]

I have the exact same issue, and currently I have also disabled reduce infill retractions, but that only helps the printer avoid infill collisions. The main area I'm having problems with the nozzle colliding due to lack of z hop, is at the end of each layer when the nozzle travels to the prime tower (if you are doing a multimaterial print or using smooth timelapse this will be enabled), as I detailed in this related issue: #3656
Because the nozzle does not z hop when travelling to the prime tower, it often scrapes on several parts on the way there, including delicate structures such as regular grid supports that can easily be knocked over by the nozzle.

[ReinhardC]

Try removing the checkmark on Process settings>Others>reduce infill retractions. This helped me get rid of some nasty infill collisions.

Thank you. I'm going to test this option. It shows promise.

I have tried using this setting, and still experience the issue.

Try changing z-hop type to normal (move up, travel, move down). The default z-hop type is slope (moves up while traveling). If this doesn't help try increasing the z-hop distance.

[ReinhardC]

I have the exact same issue, and currently I have also disabled reduce infill retractions, but that only helps the printer avoid infill collisions. The main area I'm having problems with the nozzle colliding due to lack of z hop, is at the end of each layer when the nozzle travels to the prime tower (if you are doing a multimaterial print or using smooth timelapse this will be enabled), as I detailed in this related issue: #3656 Because the nozzle does not z hop when travelling to the prime tower, it often scrapes on several parts on the way there, including delicate structures such as regular grid supports that can easily be knocked over by the nozzle.

Could be worth a try testing z-hop type 'normal' here too, but I suspect this is a different issue maybe due to a bug in gcode construction.