TL;DR: FOrcaSlicer (FOS) is a fork of Snapmaker OrcaSlicer for the Snapmaker U1. The U1 has four independent print heads, and FOS makes each one capable of carrying a different nozzle diameter and doing a different job - a fine nozzle on the visible surface, a coarse one on everything behind it, and painted color applied as a thin shell instead of a solid block of filament. Snapmaker Orca is a great slicer to build on; FOS just leans into the U1’s four-head hardware in a way stock doesn’t yet.
Everything below is verified in G-code. It’s still early, so feedback is very welcome.
Launch demo
A short walkthrough of what FOrcaSlicer does differently from stock Snapmaker OrcaSlicer, across three areas: mixed nozzle sizes, splitting the outer and inner wall onto different heads, and Color Patch mode.
The Idea: Four Heads, Four Jobs
Most multi-material slicing treats extra heads as a color feature - same nozzle, different filament. But the U1’s heads are independent hardware, so they can carry different nozzle sizes. Once you accept that, the four heads become a fabrication strategy: spend precision where it’s visible, and speed where it isn’t.
1. Outer Wall / Inner Wall Split
Stock treats “walls” as a single setting. FOS splits them into two independently assignable features:
- Outer wall (OW) on a small nozzle (e.g. 0.2 mm) - the surface you actually see and touch.
- Inner wall (IW) + infill on a larger nozzle (e.g. 0.4-0.6 mm) - nobody sees it.
- Solid infill on a larger nozzle (e.g. 0.4-0.8 mm) - it prints faster on flat top and bottom faces.
A set of gears printed with a 0.2 mm outer wall and a 0.4-0.6 mm interior has the same tooth profile as an all-0.2 mm print, but finishes in about 5 hours instead of 8.5 - even with a wipe tower running.
And it’s not only speed. You can put a different material on each: a low-friction nylon ¶ tooth flank over a stiff carbon-fiber-nylon (PA-CF) core, at the same time. One nozzle can’t do that.
2. Per-nozzle Settings
Each nozzle prints at its own line width and speed, and support and the prime tower are sized to the nozzle that actually prints them (no more a 0.2 mm tip being told to lay a 1.0 mm tower line). Each nozzle can also carry its own process preset.
3. Color Patch: Color As a Surface, Not a Volume
When you paint a region in most slicers, the whole solid volume beneath it becomes that color - buried filament you never see. Color Patch applies the painted color as a shell of a few perimeter loops and keeps the interior as base material. Same look, a fraction of the colored filament.
The fun part: shell and core can be different materials. A soft TPU grip becomes a shell that mechanically wraps a rigid PETG core - TPU won’t chemically bond to PETG, so a side-by-side paint would delaminate, but a wrap holds.
Translucent shells also give real see-through effects (think a legging over a skin-tone leg).
Being Honest About the Limits
- Layer height is still shared, bounded by the smallest nozzle in use - so a 0.2 mm outer wall pins the whole print to a fine layer height. Per-nozzle layer height is the big in-progress feature.
- The U1 firmware doesn’t support mixed-nozzle printing from the touchscreen yet - you send the job directly from the slicer. Lifting that needs a Snapmaker firmware update, which is out of my hands.
- Windows only, Snapmaker U1 only. I do not have another multi-toolhead printer to test with, and I am not a programmer nor software engineer. Windows and Snapmaker U1 are the things I have to test with.
A more detailed Wiki is also available at:
https://github.com/jiyang1018/FOrcaSlicer/wiki
How to Get It
Project repo is at:
https://github.com/jiyang1018/FOrcaSlicer
The latest release is at:
https://github.com/jiyang1018/FOrcaSlicer/releases
Dev roadmap is at:
https://github.com/jiyang1018/FOrcaSlicer-roadmap
