Support top z distance is applied with respect to model geometry, not proceeding layers #651

New Issue

MrUnknownDE · 2026-04-05T16:25:08+02:00

MrUnknownDE commented

2026-04-05 16:25:08 +02:00

Originally created by @Behem07h on 2/22/2026

Is there an existing issue for this problem?

I have searched the existing issues

OrcaSlicer Version

2.3.2-beta

Operating System (OS)

Windows

OS Version

Windows 10

Additional system information

No response

Printer

Ender 3 v2

How to reproduce

Slice the model attached, whose overhang is located at a height not divisible by the layer height (thus, the first overhang layer will be located higher than the bottom of the overhang in the actual model geometry).
Observe the supports. At a support top z distance of 0, they sit against the bottom of the overhang as defined by the model geometry, but leave a 1 layer height gap between the support interface and the overhanging layer, as the overhanging layer was rounded up to a higher position than in the actual model geometry (it was rounded up to a multiple of the layer height)

Actual results

Supports do not touch the overhanging layers when printed, nor when observed in GCode viewer, despite being sliced with a support top z distance of 0.
when sliced instead with a support top z distance of 0.16 (1 layer height), the gap in the gcode is 0.32, 2 layer heights, resulting in worsened overhang quality

this occurs regardless of whether "independent support layer height" has been enabled or not

Expected results

Support top z distance should be calculated with respect to the overhanging layers that the supports are supporting, to ensure a consistent gap to the printed layers above and thus consistent quality of supported surfaces
(else the quality of supported surfaces will vary depending on whether the model's overhang position is a clean multiple of the chosen layer height, which is an unreasonable expectation if third party models are being sliced)

Project file & Debug log uploads

custom_stab_remake_2.6-wire_bender_small(1).zip

Checklist of files to include

Log file
Project file

Anything else?

*Originally created by @Behem07h on 2/22/2026* ### Is there an existing issue for this problem? - [x] I have searched the existing issues ### OrcaSlicer Version 2.3.2-beta ### Operating System (OS) Windows ### OS Version Windows 10 ### Additional system information _No response_ ### Printer Ender 3 v2 ### How to reproduce 1. Slice the model attached, whose overhang is located at a height not divisible by the layer height (thus, the first overhang layer will be located higher than the bottom of the overhang in the actual model geometry). 2. Observe the supports. At a support top z distance of 0, they sit against the bottom of the overhang as defined by the model geometry, but leave a 1 layer height gap between the support interface and the overhanging layer, as the overhanging layer was rounded up to a higher position than in the actual model geometry (it was rounded up to a multiple of the layer height) ### Actual results Supports do not touch the overhanging layers when printed, nor when observed in GCode viewer, despite being sliced with a support top z distance of 0. when sliced instead with a support top z distance of 0.16 (1 layer height), the gap in the gcode is 0.32, 2 layer heights, resulting in worsened overhang quality this occurs regardless of whether "independent support layer height" has been enabled or not ### Expected results Support top z distance should be calculated with respect to the overhanging layers that the supports are supporting, to ensure a consistent gap to the printed layers above and thus consistent quality of supported surfaces (else the quality of supported surfaces will vary depending on whether the model's overhang position is a clean multiple of the chosen layer height, which is an unreasonable expectation if third party models are being sliced) ### Project file & Debug log uploads [custom_stab_remake_2.6-wire_bender_small(1).zip](https://github.com/user-attachments/files/25470267/custom_stab_remake_2.6-wire_bender_small.1.zip) ### Checklist of files to include - [ ] Log file - [x] Project file ### Anything else? <img width="1920" height="1080" alt="Image" src="https://github.com/user-attachments/assets/90ca9fb9-9c28-4460-84fb-b22fdbcf719b" />

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Reference: github/OrcaSlicer#651