Continous Concentric Shell for non-circular objects #2333

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MrUnknownDE · 2026-04-06T04:16:09+02:00

MrUnknownDE commented

2026-04-06 04:16:09 +02:00

Originally created by @witc-git on 8/29/2025

Is there an existing issue for this feature request?

I have searched the existing issues

When I use Concentric Top/Bottom shells it starts printing outside moving inward. After a while it will retract, lift, and move deeper into the center of the print where it starts printing again. It does this repeatedly which results in a lot of retractions, lifts and non-print moves on a top or bottom surface. Each of these stop and starts is a point of failure for bed adhesion due to curling at the line start (Ender 3V2, Ender 5S1, Ender 6, K1 Max, K1 SE). This also make seams on the shell a lot more visible than they should be.

See first layer in OrcaSlicer preview

Which printers will be beneficial to this feature?

All

Describe the solution you'd like

A solution would be to handle Concentric shells (or create a new shell type called continuous concentric) that works the way PrusaSlicer handles concentric, and the way OrcaSlicer currently handles concentric for perfect circles. It starts at the perimeter, then moves inward line by line, never retracting, lifting or relocating the print head. A shift sideways for a seam is fine, but moving more that a single line width is too much.

See first layer progress in PrusaSlcier preview

Describe alternatives you've considered

I've tried Octagram Spiral, but it also has a bunch of non-print moves.
I've tried Archimedean Chords, unless it is a perfect circle it also has non-print moves and doesn't connect to the perimeters properly.
Considered going back to Monotonic, but when it works Concentric just looks so much more polished and intentional.

Additional context

I read somewhere that the way Orca currently handles concentric is done to improve elephant's foot, personally I've never had a problem with elephant's foot no matter the shell type I used, I have constant issues (occasional failed prints, frequent hideous shells on the outsides of objects) with the start-stop method of Orca's concentric pattern.

*Originally created by @witc-git on 8/29/2025* ### Is there an existing issue for this feature request? - [x] I have searched the existing issues ### Is your feature request related to a problem? When I use Concentric Top/Bottom shells it starts printing outside moving inward. After a while it will retract, lift, and move deeper into the center of the print where it starts printing again. It does this repeatedly which results in a lot of retractions, lifts and non-print moves on a top or bottom surface. Each of these stop and starts is a point of failure for bed adhesion due to curling at the line start (Ender 3V2, Ender 5S1, Ender 6, K1 Max, K1 SE). This also make seams on the shell a lot more visible than they should be. See first layer in OrcaSlicer preview <img width="824" height="583" alt="Image" src="https://github.com/user-attachments/assets/bcab69a8-68c5-42df-b59c-cd697a07c780" /> ### Which printers will be beneficial to this feature? All ### Describe the solution you'd like A solution would be to handle Concentric shells (or create a new shell type called continuous concentric) that works the way PrusaSlicer handles concentric, and the way OrcaSlicer currently handles concentric for perfect circles. It starts at the perimeter, then moves inward line by line, never retracting, lifting or relocating the print head. A shift sideways for a seam is fine, but moving more that a single line width is too much. See first layer progress in PrusaSlcier preview <img width="824" height="583" alt="Image" src="https://github.com/user-attachments/assets/d780ad0c-1783-4727-94dc-4fa6b60f7dd5" /> <img width="824" height="583" alt="Image" src="https://github.com/user-attachments/assets/a61d5198-2f15-4824-b98b-9e4debe9c5e0" /> <img width="824" height="583" alt="Image" src="https://github.com/user-attachments/assets/5288a453-f6c4-4161-b48e-9d15edb3f2dc" /> <img width="824" height="583" alt="Image" src="https://github.com/user-attachments/assets/acf43fbf-c25e-40b6-8fc3-9cf7c086808d" /> ### Describe alternatives you've considered 1. I've tried Octagram Spiral, but it also has a bunch of non-print moves. 2. I've tried Archimedean Chords, unless it is a perfect circle it also has non-print moves and doesn't connect to the perimeters properly. 3. Considered going back to Monotonic, but when it works Concentric just looks so much more polished and intentional. ### Additional context I read somewhere that the way Orca currently handles concentric is done to improve elephant's foot, personally I've never had a problem with elephant's foot no matter the shell type I used, I have constant issues (occasional failed prints, frequent hideous shells on the outsides of objects) with the start-stop method of Orca's concentric pattern.

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Reference: github/OrcaSlicer#2333