Bambu Studio 2.9.1 Is Out: Mixed Nozzle Sizes Start With the H3C, and Bambu Lists Security Fixes
Bambu Studio 2.9.1 adds the H3C and per-region mixed nozzle sizes, H3C first, and brings the 2.8.3 and 2.8.4 beta features to the public release.
Bambu Lab released Bambu Studio 2.9.1 on November 3, its first public release since 2.8.2.61. It adds the new H3C and lets nozzles of different sizes print different regions of one model at their own layer heights, but Bambu says that feature supports the H3C first, with other printers to follow in later announcements. For other Bambu printers the release brings the 2.8.3 and 2.8.4 beta features to the public release, makes monotonic the default infill just below the top surface and, Bambu says, fixes stability and security issues.
A public release that starts mixed nozzle sizes on the H3C
Bambu says 2.9.1 supports per-region mixed nozzle diameters on the H3C first; support for other models will come in official announcements.
The release includes the 2.8.3 and 2.8.4 public-beta features, including a new monotonic default for the infill just below the top surface.
Bambu’s November 3 roadmap estimates mixed-size printing for the H2D in November 2026 and for the H2C and X2D in February 2027, later with a filament track switch.
ReportBambu Lab
Mixed nozzle sizes arrive for the H3C, and the 2.8.3 and 2.8.4 beta features go public
Bambu Lab published Bambu Studio 2.9.1 as a public release on November 3; its wiki release-notes index lists it directly above 2.8.2.61, the previous public release. Bambu says the release adds support for the H3C and brings “fixes for a number of stability and security issues”. Its headline feature, mixed nozzle diameter slicing, lets users assign nozzles of different diameters to local details and to the main body of one model, each printing at its own layer height. Bambu says “This release supports the H3C first. Information about support for other models will be provided in official announcements”, and that the slicing refactor behind it means all multi-nozzle models benefit. Color mixing changes too: Color Split has been merged into the existing mixed-color page and renamed Color Matching, which now offers Manual Mixing and Color Matching on the same page, Bambu PLA Palette is supported, and the color-mixing sublayer feature is on by default for the H3C’s 0.4 mm presets at 0.2 and 0.24 mm layer heights.
For owners of other Bambu printers, the release matters because it includes the features from the 2.8.3 and 2.8.4 public betas: an optimized top-surface monotonic path with fewer travel moves, illustrated parameter tips, a separate Initial Layer Infill Line Width, a new Archimedean spiral ironing pattern, and a new sub-top-surface setting whose default is now monotonic instead of the rectilinear pattern used before. Bambu’s release notes do not list which security issues were fixed. Site analysis, not a measurement: because a default pattern and some toolpaths changed, a project re-sliced in 2.9.1 may not match its 2.8.2 output, so re-check a known-good project before a production batch. The Crafty Catsman has not tested 2.9.1 and makes no claim about its stability or print results.
What else changes, and when the H2D, H2C and X2D catch up
Other changes Bambu lists: a TPU 75A filament preset; PVA now retracts 12 mm in one continuous movement; modifiers can apply alternating layers and a conformal fill; the tree-support tip diameter is adjustable in Developer mode; the AMS filament-backup feature is redesigned so backup can work between different subtypes and colors within a filament family, but Bambu says this is currently supported only on the H3C printer, with other models to follow in a future firmware update; and support for the Bambu Lab E1 Purifier is added. Fixes include an account being signed out unexpectedly after sending a print job, software freezes on macOS and on Linux, and the calibration page choosing presets by extruder 1’s nozzle diameter when an X2D uses nozzles of different diameters. Mixing nozzle sizes on an H3C needs nozzles of more than one diameter fitted.
When the H2D, H2C and X2D get mixed nozzle sizes: Bambu’s November 3 blog post says it is developing multi-orifice nozzle printing for the H2D, H2C and X2D and gives an estimated software timeline: without a filament track switch, November 2026 for the H2D and February 2027 for the H2C and X2D; with a filament track switch, February 2027 for the H2D and March 2027 for the H2C and X2D. Bambu calls these estimates and says the work is a low-level adaptation, because those printers’ AMS setups differ from the H3C’s. Until it ships, 2.9.1 does not offer per-region mixed nozzle sizes on those printers. H3C buyers need 2.9.1 for the new printer.
- Which security issues 2.9.1 fixes; Bambu’s release notes do not list them.
- When mixed nozzle sizes actually reach the H2D, H2C and X2D; Bambu’s dates are estimates.
- When the AMS filament-backup changes reach printers other than the H3C; Bambu says a future firmware update.
Hold off if:You were planning to buy extra nozzles or hotends for mixed nozzle sizes on an H2D, H2C or X2D: 2.9.1 supports the feature on the H3C first, and Bambu’s dates for those printers are estimates.
Update if:You use Bambu Studio with any Bambu printer: install 2.9.1 for the stability and security fixes Bambu lists, then re-slice a known-good project and compare it before a production batch.
Bambu Studio 2.9.1 — what Bambu’s release note lists
| Detail | Bambu Lab Bambu Studio 2.9.1 |
|---|---|
| Release type | Public release; note posted November 3, 2026 |
| Previous public release | 2.8.2.61, per Bambu’s release-notes index |
| New printer | H3C support |
| Mixed nozzle sizes per region | H3C first; other models in later announcements |
| Beta features now public | 2.8.3 and 2.8.4 public-beta features |
| Sub-top-surface default | Monotonic instead of rectilinear |
| AMS filament backup changes | H3C only for now |
| Security fixes | Listed but not itemized |
Sources: Bambu Studio 2.9.1 release note
Update for the fixes, then re-check a project you know well.
Install 2.9.1 for the stability and security fixes Bambu lists, then re-slice one known-good project and compare it before a production batch, because the sub-top-surface default and the top-surface paths changed.
Hold off on extra nozzles or hotends for that purpose: 2.9.1 supports the feature on the H3C first, and Bambu’s dates for the other printers are estimates.
Bambu publishes Bambu Studio 2.9.1
Bambu’s wiki release note for the 2.9.1 public release went up on November 3, and its release-notes index lists 2.9.1 directly above 2.8.2.61.
Bambu posts its mixed-nozzle roadmap
The same day, Bambu’s blog gave estimated dates for multi-orifice nozzle printing on the H2D, H2C and X2D.
Primary pages and records used for this report.
Frequently Asked Questions
Does Bambu Studio 2.9.1 let my H2C, H2D or X2D mix nozzle sizes by region in one part?▼
Not yet, according to Bambu. It says 2.9.1 supports mixed nozzle diameter printing on the H3C first, with other models to follow in official announcements. Its November 3 roadmap estimates November 2026 for the H2D and February 2027 for the H2C and X2D, or February 2027 for the H2D and March 2027 for the H2C and X2D with a filament track switch, and calls those dates estimates.
Will my existing projects slice differently in 2.9.1?▼
They may. Bambu changed the default infill for the surface just below the top skin from rectilinear to monotonic and optimized the top-surface monotonic path, so re-check a known-good project before relying on 2.9.1 for a batch. That is site analysis from Bambu’s release note, not a measurement.
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