preFlight - an incredible new slicer with even more incredible bugs (for now)

Product reviewed

Pre-Flight is a 3D printing slicer for filament printers, developed by Oozebot (US). It is a fork of PrusaSlicer, aiming to add new slicing widgets and workflows. The reviewer notes it was too buggy to use before 1.0.0, but by the time of recording version 1.0.0 is “quite usable.”

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Main features highlighted

1) Perimeter interlocking (novel structural feature)

• Designed to address weakness at layer interfaces by staggering and overextruding perimeter lines across layers.
• This helps molten plastic squish into gaps, forming diagonal bonds.
• Claimed benefit: ~5–15% part strength increase with no real change to material use or print time.
• Positioned as potentially better than “brick layer” methods:
  • avoids needing many micro Z adjustments
  • avoids some concerns associated with those techniques
• The reviewer also notes it was presented as pioneered versus similar approaches (including a comparison to Orca Slicer wall/technique variants).

2) Counterbore bridging via “sequential bridging” (quality-of-life + reliability)

• Targets a bridging failure mode where gaps that should bridge straight instead cause stringing or failed “unsupported” counterbore/bore details.
• In the slicer:
  • select the underside face
  • choose how many sequential bridge layers to use
• Guidance given:
  • for small counterbores up to ~6 mm diameter, two bridge layers is “perfectly fine”
  • larger bores need more layers

3) “Nip and tuck” seams (seam placement to protect precision)

• Adjusts the start and/or end of the perimeter slightly (“nip” / “tuck”) to create a small V-shaped feature.
• This aims to bury the seam away from critical geometry.
• Claimed to preserve precision even if it doesn’t hide seams visually.
• Compared to scarf seams:
  • scarf seams still better for visual hiding
  • “nip and tuck” is better for practical accuracy

4) Support workflow upgrades

• Supports manual painting using different styles:
  • grid, organic, or snug
• Supports can be mixed on the same model.

5) Integration with PrusaSlicer configuration wizard

• Pre-Flight can “plug into” PrusaSlicer’s config wizard for printer/filament profile loading.
• The reviewer finds profile behavior inconsistent, with some new-feature interactions not applying correctly.

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Pros (what the reviewer liked)

• Real innovation in structural/geometry features:
  • Perimeter interlocking is compelling, with a noticeable change in print behavior/weight.
  • Sequential bridging reduces reliance on sacrificial bridges/drilling (at least for the demonstrated case).
  • Nip and tuck seams are praised as a practical improvement for precision parts.
• Produces strong, attractive prints when the workflow works.
• The reviewer “still kind of loves it,” viewing it as experimental and forward-looking.

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Cons (major issues / bugs / downsides)

The reviewer repeatedly emphasizes that Pre-Flight is still buggy and unstable, despite usability improvements in 1.0.0.

Key problems mentioned

• Perimeter interlocking/overlocking sometimes doesn’t respond to imported profiles
  • example: PrusaSlicer core 1 profile not reacting
• Import/conversion from other slicers is limited
  • Orca Slicer import exists, but many values don’t carry over correctly (especially filament profiles), requiring rebuilding profiles from scratch
• Multiple “host” issues, including:
  • Modifiers breaking things
  • Random missing layers
  • Infill phase-through perimeters unless overlocking perimeter setting is changed from default (and only on some geometry)
• Performance issues
  • interlocking parameters can make slicing chuggy
  • preview becomes laggy and GPU intensive when zooming
    • tested even with 64 GB RAM, i9, RTX 4070
• Specific filament speed bug (TPU/flex)
  • Volumetric print speed malfunctioned:
    • lowering volumetric flow to ~3 mm³/s caused printer behavior equivalent to roughly ~300 mm/s
  • Mentioned as fixed in a beta for 1.0.1, released shortly before the review.

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User experience / workflow notes

Interface and navigation

• Layout resembles PrusaSlicer, with:
  • left-side tabbed columns
  • right-side model manipulation tools
• Reviewer finds the setup redundant and hard to navigate due to too many settings.
• Accordion mode exists but “doesn’t help much”; the reviewer mostly uses top tabs.
• Hotkeys exist for most commands—reviewer recommends learning them.

Setup difficulty

• Getting a “final working” configuration was described as harder than expected, involving scratch-building profiles due to broken/ineffective imports.

Stability guidance

• The reviewer frames it as: “Save often and crash even more often”, implying crashes and print disasters are possible.

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Comparisons made

Versus PrusaSlicer (base + configuration)

• Pre-Flight is derived from PrusaSlicer and shares UI concepts and config wizard integration.
• However, some PrusaSlicer profiles/settings don’t behave correctly with Pre-Flight’s new features.

Versus Orca Slicer

• Orca is the reviewer’s current “go-to.”
• Similar structural effects exist in Orca (review references prior approach), but Pre-Flight is described as:
  • more geometry-robust (Orca’s method can be “messed up” by external part geometry)

Versus brick layers

• Pre-Flight’s interlocking is said to avoid the brick layer approach’s heavy micro Z adjustment requirements.

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Numerical results / ratings / measurements mentioned

• Strength claim: 5–15% (estimated/claimed by the feature concept)
• Test piece weights (same part variant family, as described):
  • Pre-Flight perimeter overlocking/interlocking: 38 g
  • 100% rectilinear infill: 44 g
  • 100% perimeters: 44 g
  • Orca “similar staggered perimeter effect” (custom Orca settings): 45 g
• Reviewer interpretation: Pre-Flight part appears ~7 g lighter, suggesting it still contains considerable air; the strength difference isn’t verified yet.
• Counterbore guidance: effective range ~up to 6 mm diameter with 2 bridge layers
• TPU speed bug example:
  • volumetric speed reduced to ~3 mm³/s
  • resulted in behavior akin to ~300 mm/s

(No formal star rating or overall numeric score is given.)

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Concrete test described: Violent Crumble / TPU chassis

The reviewer printed a combat robot chassis for an unrestricted Antweight variant using 72D TPU (durable semi-flex).

• Print plan leveraged:
  • Interlocking perimeters
  • Sequential bridging (to avoid drilling sacrificial bridges)
  • Manual supports mixing grid and organic
• Outcome:
  • Final print looks “really good” and appears strong
  • Reviewer admits the time spent getting it working was large, and the strength advantage vs Orca remains unproven

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Overall verdict / recommendation (as stated)

• Recommendation: Don’t switch yet (“probably not”) for most users.
• Rationale: despite innovative features, Pre-Flight is still a “buggy hot mess” with:
  • import/profile issues
  • missing layers
  • seam/perimeter interactions
  • serious performance lag
• Who should try it:
  • users who like experimenting
  • users who can tolerate crashes/print disasters
  • users willing to support a small team improving the slicer The reviewer notes bugs have improved since late last year and mentions ongoing fixes.

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Unique points mentioned (deduplicated)

• Pre-Flight is a PrusaSlicer fork from Oozebot (US startup).
• Was buggy before; 1.0.0 now usable.
• UI layout is a hybrid of PrusaSlicer and Orca concepts, with redundant/awkward navigation.
• Hotkeys exist for many tools (recommended to learn).
• Perimeter interlocking:
  • tackles layer-interface weakness via staggered/overextruded offset perimeters
  • claimed 5–15% strength increase at similar material/time
  • positioned as potentially superior to brick layers
  • compared to Orca’s approach as more geometry-correct
• Interlocking/perimeter testing produced surprising weight differences (38 g vs ~44–45 g).
• Sequential bridging for counterbores:
  • fixes bridging failures
  • requires selecting number of sequential bridge layers
  • example: 2 layers up to ~6 mm diameter; larger needs more
  • avoids sacrificial bridge drilling
• Nip and tuck seams:
  • V-shaped seam burying by nudging perimeter start/end
  • better for precision than scarf seams (though not visually)
• Manual support painting: grid/organic/snug, including combinations.
• Integration attempts:
  • config wizard can load profiles, but some profiles don’t respond correctly to new features
  • Orca import exists but is incomplete/buggy, especially for filament profiles
• Major bugs/glitches:
  • modifiers breaking things, missing layers, infill-through-perimeters
  • overlocking sensitivity issues from defaults
  • slicing/preview performance lag (GPU-intensive zoom preview)
• TPU-specific bug:
  • volumetric speed setting caused absurdly fast behavior
  • fixed in beta (1.0.1)
• Despite bugs, reviewer finds it promising, but most should stick with Orca Slicer for now.

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Speakers / perspectives

• Primary speaker: Angus (Makers Muse) — all key product evaluation, feature tests, comparisons, and overall recommendation are from the same reviewer.