Known Limitations¶

Current as of v2.3.2-fos.8.5.6.

This is a complete list, including items with no fix scheduled. Where a workaround exists, it is given. Nothing here is a crash - every item below is a limitation you can work around or live with.

Slicing¶

Layer height is shared across all four nozzles¶

Layer height and initial layer height are a single global setting. All nozzles print on one layer grid, and the grid is bounded by the smallest nozzle you actually use - so you cannot ask a 0.2 mm tip to lay a 0.6 mm layer. A 0.2 mm outer wall nozzle forces the whole print to a fine layer height even though the 0.8 mm nozzle could lay much thicker layers. The limit follows your assignments: use only larger nozzles and the allowed range opens up.

Note that a per-object filament counts too - an object's filament is its outer wall. If the allowed layer height looks too low, check each object's filament in the object list, not just the Filament for Features dropdowns - an object whose outer wall is on the 0.2 mm nozzle keeps the ceiling low even if the global assignments all use larger nozzles.

Impact: the speed benefit of a large infill nozzle is capped. You get the wider line and the faster speed, but not the taller layer.

Status: this is the central piece of work now in progress - per-nozzle layer heights within a single object. It is the reason FOrcaSlicer exists in its current form. Not in this release.

Workaround: none. Choose your smallest nozzle knowing it sets the layer height for everything.

Thick internal bridges can extrude far taller than the layer height¶

With Thick internal bridges enabled, an internal bridge is extruded at a height of nozzle diameter x the square root of the bridge flow ratio with no clamp against the layer height. Under mixed nozzles this can be extreme: a 0.8 mm nozzle on a 0.1 mm layer produces a single 0.8 mm-tall extrusion - eight times the layer height - that overlaps the sparse infill beneath it.

This is upstream OrcaSlicer behavior, not a FOrcaSlicer bug. Stock Orca with uniform 0.8 mm nozzles at 0.24 mm layers produces the same 0.8 mm bridge (3.3x layer height) with the same overlap. Mixed nozzles change the magnitude, not the mechanism.

Workaround: disable Thick internal bridges when the solid infill nozzle is much larger than the layer height.

Status: a layer-height-aware clamp is under consideration.

Filament flow limits still largely follow the Outer Wall nozzle¶

As of 8.5, line width and speed are resolved per nozzle - a large nozzle now gets both its wider line and its own speed, and support and the prime tower are sized per nozzle as well. Filament-side values are further behind. Filament profiles are offered per slot, filtered by that slot's nozzle diameter, but the filament flow limits applied when slicing still largely follow the Outer Wall nozzle's profile rather than each nozzle's own. A 0.8 mm nozzle assigned to sparse infill runs at its own line width and speed, but not necessarily at the full volumetric flow a 0.8 mm nozzle is capable of.

Impact: you get the wider line and the faster speed from a large nozzle, but not necessarily its full flow potential.

Status: planned. Tied to the same per-nozzle work as layer height.

Support layer height follows Nozzle 1¶

Support line width and speed are now sized per nozzle (see the 8.4 support fixes in the release notes), but support layer height still follows Nozzle 1. A 0.8 mm nozzle assigned to support can be asked to print support at Nozzle 1's layer height.

Status: consistent with the shared layer grid above, and resolved by the same per-nozzle layer-height work.

First-layer line width and speed are global¶

Initial (first) layer line width and initial layer speed are a single global value, not resolved per nozzle - the first layer is typically laid down by several tools. Every other feature width and speed is per nozzle as of 8.5.

Status: low priority. Per-tool first-layer handling would be a new feature.

Color Patch¶

Curved surfaces may render as a solid infill pattern rather than shell loops¶

On spheres, cones, and cylinders, a Color Patch region may be filled using the top solid infill pattern instead of resolving into separate inner wall loops and infill. Flat-faced geometry is the tested and reliable case.

Status: under investigation. Lower priority given the U1's typical flat-faced use cases.

Workaround: none. Check curved-surface color patches in preview before committing to a print.

CL=1 seam artifacts at arc endpoints¶

With seam position set to Nearest or Aligned, a single color loop can show a visible artifact where the loop closes on a curved surface.

Workaround: set seam position to Random. This resolves it.

Status: a dedicated seam geometry fix for CL=1 is planned.

Top/bottom boundary staircase¶

Where a painted region wraps from a side wall onto a top or bottom face, the color boundary steps layer by layer rather than following a clean diagonal.

This is the same solid-shell propagation stock OrcaSlicer uses for any multi-material top shell - not a FOrcaSlicer regression.

Status: the intended fix is bisector-based separation, so the boundary follows the angle that splits the two surface normals, like a mitre joint. This requires the slicer to track which layers have given up area to a painted region. Planned, not started.

Color patch may not update on a freshly painted object¶

Occasionally, a newly painted object does not reflect a mode change until you toggle it.

Workaround: switch Original -> Color Patch once. Low frequency.

Presets and UI¶

Nozzle tabs show only one tab after adding a U1 preset¶

After you add a U1 printer preset, the per-nozzle notebook shows only one tab. Clicking away to another settings page and back populates the rest.

Workaround: click to another page and back. Status: cosmetic; the presets are created correctly.

New printer presets inherit a single layer-height range¶

When you create a printer preset (PTP), FOrcaSlicer inherits one layer-height range from the base preset by nozzle size, rather than deriving it per nozzle. An inherited range that is wider or narrower than the nozzle can actually print will drive the auto-adjust prompt, or the hard limit, at slice time.

Workaround: inspect the min and max layer height before saving a new PTP - see Before You Print for the inherited defaults by nozzle size.

Status: per-nozzle range derivation is tied to the per-nozzle layer-height work.

The Verify nozzle sizes check gates the Print and Export G-code file buttons, but it does not gate the Export G-code... menu option, which can export a file without the check.

Impact: minimal. The Snapmaker U1 firmware cannot print a mixed-nozzle file anyway, so a file exported this way still will not run on the machine.

Status: a minor fix to gate the menu option is planned.

Installation¶

Drag-and-drop STL fails on a fresh machine¶

On a computer that has never had OrcaSlicer installed, dragging an STL onto the FOrcaSlicer window may do nothing.

Workaround: use File -> Import, which always works. Running stock OrcaSlicer once may fix it - it appears to register the Windows shell handler - but this is not guaranteed.

Status: low priority. The cause is currently unknown.

Printer¶

The printer touchscreen cannot start a mixed-nozzle print¶

The Snapmaker U1 firmware does not yet support printing with mixed nozzle sizes. You can still send a mixed-nozzle project to print directly from the slicer - that path works. But once the project has been sent to the printer, you cannot use the printer's touchscreen to start a mixed-nozzle job: the firmware blocks it.

Workaround: send mixed-nozzle prints directly from FOrcaSlicer rather than starting them from the touchscreen.

Status: this requires Snapmaker to release firmware that lifts the guard. It is outside FOrcaSlicer's control.

Platform¶

No Linux build¶

Windows and macOS builds are provided - the macOS build is a universal Intel + Apple Silicon DMG (macOS 12 Monterey or later). There is no Linux build yet; build from source.

Snapmaker U1 only¶

FOrcaSlicer is not tested against, and not intended for, any other printer.

macOS¶

The app is unsigned and unnotarized¶

The project has no Apple Developer certificate, so macOS blocks the first launch with "FOrcaSlicer can't be opened because Apple cannot check it for malicious software." The download is not damaged.

Workaround: after moving the app to Applications, clear the quarantine flag once - xattr -dr com.apple.quarantine "/Applications/FOrcaSlicer.app" - or open it via System Settings -> Privacy & Security -> Open Anyway (the Control-click bypass was removed in macOS 15). See Download and Install.

Status: blocked on an Apple Developer certificate.

Dark mode can render light-on-light on first launch¶

In dark mode, the notebook and nozzle-diameter labels can show as light text on a light-grey background the first time the app starts.

Workaround: switch the system appearance to light and back to dark - it corrects for the session.

Status: cosmetic, macOS only. The app reads the system appearance before its window exists and does not re-check it.

Not Fully Validated¶

These work individually. Used together they are untested - they will not stop you, but verify your own combination before a long print.

Mixed nozzles and Color Patch and several different feature extruders (outer wall, inner wall, solid infill, sparse infill all on different nozzles) all at once.

Roadmap¶

In rough order of priority:

Item	Status
Per-nozzle line width and speed	Done in 8.5
Per-nozzle support and prime-tower sizing	Done in 8.4
Per-nozzle process preset (PRP) selection	Done in 8.5
Per-nozzle layer height within one object	In progress - the current focus
Per-nozzle filament flow limits	Planned - tied to the per-nozzle layer-height work
Per-nozzle layer-height range on new presets	Planned - with the layer-height work
Per-nozzle first-layer line width and speed	Low priority
Mixed-nozzle printing from the U1 touchscreen	Blocked on Snapmaker firmware
Gate the Export G-code menu option behind nozzle verify	Planned - minor
Bisector color boundary (removes the staircase)	Planned
Dedicated seam geometry for CL=1	Planned
Layer-height-aware clamp on thick internal bridges	Under consideration
Curved-surface Color Patch behavior	Under investigation
Drag-and-drop shell registration	Low priority - cause unknown
Chinese localization of this wiki	Machine translated, human proof read