Most Orca Slicer users only scratch the surface of what the software can do. They load a model, select a quality preset, click slice, and print. But underneath the default interface lies a deep well of advanced features that can transform your print quality, dramatically reduce print times, and enable workflows that are simply not possible with other slicers. This guide covers ten advanced features that every serious Orca Slicer user should understand and incorporate into their workflow. Each section explains what the feature does, why it matters, and exactly how to configure it for optimal results.
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1. Tree Supports
Tree supports are Orca Slicer's most visually impressive feature and arguably its most practically useful one for complex models. Unlike traditional line or grid supports that grow straight up from the build plate in dense columns, tree supports create organic, branching structures that reach upward and outward to precisely cradle overhang regions. The trunk grows from the build plate at an angle, and branches split off at configurable intervals to reach multiple overhang areas from a single base.
The practical advantages are significant. Tree supports use 40-60% less material than equivalent traditional supports because the branching structure is inherently efficient. They are far easier to remove because the contact points with the model surface are minimal and can be configured to use a thinner interface layer. The support scars they leave on the printed surface are smaller and easier to sand smooth. On complex organic models like figurines, busts, and mechanical assemblies with internal overhangs, tree supports are often the difference between a successful print and a failed one.
To configure tree supports in Orca Slicer, navigate to Print Settings > Support and select "Tree (Auto)" as the support type. The key parameters to tune are the branch angle (45-55 degrees works well for most models), branch diameter (2-3mm provides good stability), branch tip diameter (0.6-0.8mm for easy removal), and tree wall count (1 wall for easy removal, 2 walls for better stability on tall supports). Enable "Support on build plate only" for models where internal supports would be impossible to remove. The tree support algorithm runs during slicing and can take longer than traditional support calculation, especially on complex models, but the improvement in material usage and post-processing time more than compensates.
2. Scarf Joint Seam
Every layer of a 3D print starts and stops at a seam point, creating a visible line that runs vertically along the surface. Traditional seam strategies (aligned, random, nearest) all leave some visible mark. The scarf joint seam is Orca Slicer's unique solution: instead of starting and stopping extrusion abruptly, it gradually ramps extrusion up at the start of the perimeter loop and gradually ramps it down at the end, creating a feathered overlap that is dramatically less visible than a conventional seam.
Enable scarf joint in Print Settings > Quality > Seam. Set the scarf joint start length to 10-20mm, the scarf joint angle to 20-35 degrees, and enable scarf joint for contour. The length determines how far the ramp extends along the perimeter, with longer values producing a more gradual transition. The angle controls the slope of the ramp, with shallower angles creating a less visible transition but requiring more precise extrusion control. On printers with excellent pressure advance calibration, you can use shorter lengths and steeper angles because the extruder responds quickly to flow changes.
Pro Tip: Scarf joint seam works best on circular and cylindrical surfaces. For models with sharp corners and complex perimeter shapes, the aligned seam may still produce better results because the scarf ramp can create slight surface irregularities on flat walls. Test both options on your specific model geometry and examine the results under side lighting to see which produces the cleaner surface.
3. Adaptive Layer Height
Not every region of a model benefits from the same layer resolution. A flat vertical wall looks identical at 0.12mm and 0.24mm layer height because the layer lines are equally spaced either way. But a shallow curve or a nearly horizontal slope shows dramatic quality improvement with thinner layers. Adaptive layer height analyzes the geometry of your model and dynamically adjusts layer thickness based on the surface curvature at each height.
Enable adaptive layer height in Print Settings > Layers and Perimeters > Adaptive Layer Height. Set the minimum layer height to 0.08mm (or your printer's practical minimum, typically nozzle_diameter * 0.1), the maximum layer height to your nozzle diameter times 0.75, and the quality slider to 0.5 for a balanced approach. A quality setting of 0.0 maximizes time savings with minimal quality preservation, while 1.0 minimizes time savings but maintains maximum quality on curved surfaces.
The time savings are substantial. On a model that combines vertical walls with curved domes and shallow slopes, adaptive layer height typically reduces print time by 25-35% compared to using a uniformly thin layer height. The printed result is visually indistinguishable from a constant thin-layer print on the curved surfaces, while the flat regions print faster with thicker layers. This feature is especially valuable for models like helmets, vases, architectural models, and any geometry that combines flat and curved surfaces.
4. Arc Fitting (G2/G3)
Standard G-code represents curves as sequences of tiny straight-line segments (G1 moves). A circle 50mm in diameter might be approximated by hundreds of short linear moves. Arc fitting converts these sequences into true arc commands (G2 for clockwise, G3 for counter-clockwise), which offers several advantages: smaller G-code files, smoother motion on arc-capable firmware, and reduced computational load on the printer's motion controller.
Enable arc fitting in Print Settings > Other > Arc Fitting. Set the resolution to 0.05mm for high-quality curves or 0.1mm for a balance between quality and performance. The maximum arc radius should be set to 1000mm and the minimum to 0.1mm. Orca Slicer will analyze the generated toolpath and replace qualifying linear segment sequences with arc commands wherever possible.
This feature requires firmware support. Klipper supports arcs natively through the [gcode_arcs] module (add [gcode_arcs] to your printer.cfg if not already present). Marlin supports arcs if compiled with ARC_SUPPORT enabled. RepRapFirmware supports arcs by default. If your firmware does not support arcs, enabling this feature will cause motion errors, so verify compatibility first. On compatible firmware, arc fitting typically produces 10-20% smaller G-code files and noticeably smoother curves on circular features.
5. Object-by-Object Cancellation
When printing multiple objects on the same build plate, a failure on one object traditionally means either wasting the rest of the build plate or risking the nozzle dragging through the failed print's debris and ruining adjacent parts. Object-by-object cancellation solves this by embedding markers in the G-code that identify which moves belong to which object, allowing you to cancel individual objects mid-print.
Enable this feature by checking "Label objects" in Print Settings > Other. This causes Orca Slicer to insert EXCLUDE_OBJECT_DEFINE and EXCLUDE_OBJECT_START/EXCLUDE_OBJECT_END markers around each object's G-code. On Klipper, add [exclude_object] to your printer.cfg to enable the firmware-side handling. On your web interface (Mainsail or Fluidd), you will see individual objects listed that you can click to exclude during printing.
This feature is indispensable for production runs. If you are printing 20 parts and one detaches from the bed at layer 50, you can cancel just that part and continue printing the remaining 19. The printer skips all moves associated with the cancelled object, preventing nozzle collisions with the failed print. On Marlin firmware, the equivalent feature is "Cancel Objects" which requires a compatible firmware build and OctoPrint with the Cancel Objects plugin.
6. Modifier Meshes
Modifier meshes allow you to apply different print settings to specific regions of a model without splitting the model into separate parts in your CAD software. You create a simple shape (box, cylinder, sphere, or custom mesh) and position it to overlap the region you want to modify. Within that region, you can override infill density, wall count, layer height, speed, and other parameters.
Practical applications include: increasing infill density around bolt holes for better thread engagement, reducing wall count in non-visible internal regions for faster printing, adding extra perimeters around snap-fit features for strength, and using different infill patterns in load-bearing versus non-load-bearing regions of a single part. Right-click on a model in Orca Slicer and select "Add Modifier" to create a modifier mesh. Position and scale it to cover the target region, then right-click the modifier and select the settings you want to override.
For advanced use, you can stack multiple modifier meshes to create complex setting gradients across a single part. For example, you might use one modifier to increase infill in a stressed region and another to add extra walls around a cosmetic surface, all within a single print without splitting the model. This workflow is far more efficient than the alternative of manually splitting models in CAD and reassembling them on the build plate with different settings.
7. Per-Filament Pressure Advance
Pressure advance (Klipper) or linear advance (Marlin) compensates for the delay between extruder motor movement and actual filament flow from the nozzle. Different filaments require different PA values due to varying viscosity, compressibility, and melt characteristics. Orca Slicer allows you to store PA values in each filament profile, so switching from PLA to PETG automatically applies the correct PA value through a G-code command at the start of the print.
To configure this, open your filament profile and navigate to the Advanced section. Enter the calibrated PA value in the "Pressure advance" field. When Orca Slicer generates G-code, it inserts a SET_PRESSURE_ADVANCE ADVANCE=X.XXX command (for Klipper) or M900 K=X.XXX command (for Marlin linear advance) at the beginning of the print. This overrides whatever value is set in your firmware configuration, ensuring the correct value is always used for the loaded filament.
This per-filament approach is superior to setting PA in your firmware config because firmware-level PA applies globally and must be manually changed when switching filaments. With Orca Slicer's per-filament PA, you can maintain a library of calibrated filament profiles that each carry their own PA value, smooth time, and other filament-specific tuning parameters. This eliminates the need to re-calibrate or manually edit firmware settings every time you change materials.
8. Ironing and Monotonic Infill
Ironing passes the hot nozzle over top surfaces at a reduced flow rate, melting and smoothing the surface layer. The result is a top surface that looks almost injection-molded, with minimal visible infill pattern and a smooth, glossy finish. In Orca Slicer, enable ironing in Print Settings > Quality > Ironing and set the ironing flow to 10-15%, speed to 50-80mm/s, and spacing to 0.1mm. Use "Top surfaces only" to iron the topmost surface of each region.
Monotonic infill complements ironing by controlling the direction of top solid layer extrusion. Standard infill alternates direction between adjacent lines, creating a visible pattern of light and dark bands when viewed at an angle due to how light reflects off the slightly different surface angles. Monotonic infill forces all adjacent lines to be extruded in the same direction, eliminating the banding effect and producing a uniform surface appearance even without ironing.
Enable monotonic infill in Print Settings > Infill > Top Surface Pattern and select "Monotonic." Combined with ironing, this produces the best possible top surface quality in FDM printing. The trade-off is a slight increase in print time (5-10% for monotonic infill, 10-20% for ironing on large top surfaces), but for visual parts, display models, and mating surfaces, the improvement in surface quality is worth every extra minute of print time.
9. Conditional Custom G-code
Orca Slicer's custom G-code fields support variable substitution, conditional logic, and mathematical expressions, enabling dynamic G-code that adapts to print parameters. This goes far beyond simple start and end scripts. You can insert G-code at layer changes, tool changes, and specific height thresholds, with the content varying based on conditions you define.
Common advanced use cases include: adjusting fan speed at specific layers for better bridging, triggering timelapse camera positioning at layer changes, changing LED colors based on print progress, inserting pause commands at specific heights for embedding magnets or nuts, and modifying temperatures mid-print for multi-material workflows without a tool changer.
Conditional G-code example
;AFTER_LAYER_CHANGE
;[layer_z]
{if layer_z == 0.2}M117 First layer complete{endif}
{if layer_z > 10 && layer_z < 10.5}M0 Insert magnet now{endif}
{if layer_num % 50 == 0}M117 Progress: {layer_num}/{total_layer_count}{endif}
; Timelapse positioning for Klipper
TIMELAPSE_TAKE_FRAME
The variable system in Orca Slicer exposes dozens of parameters including [layer_z], [layer_num], [total_layer_count], [nozzle_temperature], [bed_temperature], [filament_type], and many more. You can use these in conditional expressions to create intelligent G-code that responds to the specific characteristics of each print. This is particularly powerful for Klipper users who can call custom macros with parameters derived from Orca Slicer's variables.
10. Flow Rate Dynamics and Calibration
Orca Slicer includes a sophisticated flow dynamics calibration system that goes beyond simple flow rate percentage adjustment. The flow dynamics model accounts for the relationship between print speed, nozzle temperature, and actual volumetric flow rate. At higher speeds, the extruder must push more filament through the nozzle per unit time, and if the hotend cannot melt filament fast enough, under-extrusion occurs. The flow dynamics calibration maps this relationship for your specific hotend and filament combination.
Run the flow dynamics calibration from Calibration > Flow Dynamics. The test prints a series of walls at increasing speeds, allowing you to identify the maximum volumetric flow rate your hotend can sustain before quality degrades. Enter this value as the maximum volumetric speed in your filament profile. Orca Slicer will then automatically limit print speeds to ensure the maximum volumetric flow rate is never exceeded, preventing under-extrusion at high speeds without unnecessarily limiting speed on features that require less flow.
This feature is especially important for high-speed printing. A standard V6-style hotend typically maxes out around 12-15mm3/s for PLA, while high-flow hotends like the Rapido or Dragon HF can sustain 25-40mm3/s. Without flow dynamics calibration, setting a flat print speed of 300mm/s will result in under-extrusion on wide extrusion widths where the volumetric demand exceeds the hotend's capacity. With calibration, Orca Slicer intelligently reduces speed in high-demand areas while maintaining maximum speed everywhere else, resulting in the fastest possible print time without quality compromises.
These ten features represent the depth of control that Orca Slicer provides to power users. Implementing even a few of them will noticeably improve your print quality and efficiency. For getting started with Orca Slicer, see our complete setup guide, and for printer-specific tuning, check our optimized profile collection for the Bambu Lab X1C, Prusa MK4, Creality K1, and Voron 2.4.