Feature Request: Support for Continuous Print Paths for Clay and Large Format Additive Manufacturing (LFAM)

[Moeewe]

I would like to propose a Continuous Print Path feature, which is essential for Clay and Large Format Additive Manufacturing (LFAM).

Why is this important?

• Challenge with large extruders: Many industrial 3D printing systems, especially large-scale pellet extruders or metal printing processes, lack mechanical retraction. Stopping and restarting extrusion leads to material defects such as oozing, blobs, or inconsistent deposition.
• Current workarounds are insufficient: The Spiral Vase Mode already provides continuous extrusion but is limited to thin-walled structures. There is no existing option to print complex, infill needing geometries with a seamless, uninterrupted toolpath.
• Commercial solutions exist, but no Open Source alternative: Proprietary software like AiSync or Adaxis already implements continuous print paths, but there is no open-source equivalent. Adding this functionality to Orca Slicer would be a significant step forward for the community, particularly for research institutions and industrial users.

We are actually not far from the goal. One key issue is ensuring that infill patterns—such as rectilinear infill—remain continuous and do not unintentionally start generating bridging areas mid-print (as seen in the screenshots). To solve this, a second seam should be enabled that connects the infill with the outer wall. In cases where multiple walls are present, the seam should extend across several walls to maintain continuity. If these seams could be treated as scarf joints, we would effectively achieve a fully continuous print path.

The screenshots illustrate the current limitations and what is already possible. With these adjustments, we could enable a mode where extrusion never stops, making LFAM printing far more reliable and efficient.

I’d love to hear your thoughts on this and would be happy to contribute to its development!

[Moeewe]

Hey there, just wanted to kindly follow up on this. I’m curious if this idea has been considered or is already on the roadmap? I’ve seen a few similar workflows that could benefit from this, and I’d be happy to provide more detail or examples if helpful. Appreciate all the work you’re doing!

[jewmat]

Hi all — we’re also using OrcaSlicer for non-FFF extrusion workflows, specifically 3D concrete / mortar printing (similar constraints to clay/LFAM). Our extrusion hardware is a screw/pump system, with wide beads and relatively large layer heights. In this setup, continuous deposition is critical: any unplanned stop-start, mid-wall jump, or extra travel tends to leave a visible defect or a weak spot.

Right now, getting something close to a continuous toolpath requires a lot of trial-and-error across many settings, and even then we still regularly see unwanted interruptions (path reordering, travel segments, broken perimeters) that make “single continuous pass per layer” hard to achieve outside of vase mode.

What we’d love to see is a simple option / mode (e.g. “Continuous Path / Clay / 3DCP mode”) that explicitly prioritizes:
• continuous deposition whenever geometrically possible,
• predictable path ordering (avoid mid-wall jumps),
• “one continuous pass per layer” behavior beyond vase mode (except for unavoidable seams / layer transitions),
• minimizing unnecessary travel in ways that support stable extrusion (retraction can still be useful in some cases; the key is avoiding extra moves and interruptions).

Additionally, it would be amazing to have better built-in support for non-filament feed models (screw/piston extrusion), including more direct ways to map volumetric flow to a screw RPM / piston feed rate. Orca already has a “screw/pellet-style” approach for granular plastic workflows, and maybe that could be a useful starting point to adapt. For now, we’re using filament/nozzle diameters as a workaround to map our screw RPM to “E”, and it’s workable — but a dedicated model would be a big step forward.

If the project is open to exploring these features (continuous-path mode + improved feed modeling), OrcaSlicer could become a go-to tool for many enthusiasts and teams trying to achieve reliable continuous-print extrusion beyond standard FFF.

We’re happy to help with data and testing: provide representative STL models + config bundles, preview screenshots showing where the path breaks, and real machine feedback. We can also assist with calculations, implementation support, and validation experiments—whatever is helpful.

If there’s a preferred format for test cases (models + settings + expected behavior), tell us and we’ll prepare a minimal reproducible set.