Extreme speed change (+2000%) at layer with overhang #1079

New Issue

MrUnknownDE · 2026-04-05T16:46:46+02:00

MrUnknownDE commented

2026-04-05 16:46:46 +02:00

Originally created by @JustusRijke on 1/14/2026

Is there an existing issue for this problem?

I have searched the existing issues

OrcaSlicer Version

2.3.1

Operating System (OS)

Windows

OS Version

10

Additional system information

No response

Printer

Bambu X1C and P1S

How to reproduce

Create a model with an overhang, with dimensions roughly like the one in the attached project file.

Actual results

At the position where the support ends, layer adhesion is bad, causing the print to be very weak. This seems to be due to a sudden extreme speed change at the point where the overhang starts. The speed at that point is +/-200 mm/s instead of 10 mm/s, so about 20× faster.

Expected results

Print speed (of the non-overhanging part) should be identical to previous and next layer.

Project file & Debug log uploads

orcaslicer_test_overhang_speed_FAIL.zip

Checklist of files to include

Log file
Project file

Anything else?

Changing the geometry slightly (e.g., changing the width over the overhang from 4 > 3 mm) removes the strange speed change.

We detected this first at Bambu Studio 2.4.0.70 (issue link), and then tried to reproduce with Orcaslicer 2.3.1, with more or less the same result.

Printers: issue reproduced on X1C and P2S

Profile:

Bambu X1C
Bambu PLA Basis (but also reproducable with Bambu PETG and other vendor filaments/filement types)
0.20 mm Standard profile

Modifications:

Enabled support (disabling it still shows the problem, though)

We have identified this issue using Bambu filament (PETG, PLA) but also filaments from other suppliers, leading us to think the problem is with the slicer.

*Originally created by @JustusRijke on 1/14/2026* ### Is there an existing issue for this problem? - [x] I have searched the existing issues ### OrcaSlicer Version 2.3.1 ### Operating System (OS) Windows ### OS Version 10 ### Additional system information _No response_ ### Printer Bambu X1C and P1S ### How to reproduce Create a model with an overhang, with dimensions roughly like the one in the attached project file. <img width="540" height="374" alt="Image" src="https://github.com/user-attachments/assets/024e5945-16f3-474a-8f78-8683adbc2861" /> ### Actual results At the position where the support ends, layer adhesion is bad, causing the print to be very weak. This seems to be due to a sudden extreme speed change at the point where the overhang starts. The speed at that point is +/-200 mm/s instead of 10 mm/s, so about 20× faster. <img width="1445" height="823" alt="Image" src="https://github.com/user-attachments/assets/4fd87ffd-75ba-4a03-8101-7d3005ca43cc" /> <img width="1445" height="823" alt="Image" src="https://github.com/user-attachments/assets/fd302e94-56ea-4e01-b532-faff8aa595bc" /> ### Expected results Print speed (of the non-overhanging part) should be identical to previous and next layer. ### Project file & Debug log uploads [orcaslicer_test_overhang_speed_FAIL.zip](https://github.com/user-attachments/files/24615821/orcaslicer_test_overhang_speed_FAIL.zip) ### Checklist of files to include - [ ] Log file - [x] Project file ### Anything else? Changing the geometry slightly (e.g., changing the width over the overhang from 4 > 3 mm) removes the strange speed change. We detected this first at Bambu Studio 2.4.0.70 ([issue link](https://github.com/bambulab/BambuStudio/issues/9366)), and then tried to reproduce with Orcaslicer 2.3.1, with more or less the same result. Printers: issue reproduced on X1C and P2S Profile: - Bambu X1C - Bambu PLA Basis (but also reproducable with Bambu PETG and other vendor filaments/filement types) - 0.20 mm Standard profile Modifications: - Enabled support (disabling it still shows the problem, though) We have identified this issue using Bambu filament (PETG, PLA) but also filaments from other suppliers, leading us to think the problem is with the slicer.

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Reference: github/OrcaSlicer#1079