03 slice

3. Slice

Click 1. Slice in the panel. The plugin picks the geometry (if not already selected), runs the slice pipeline, and bakes the output into Rhino layers under 3DP::*.

📷 Rhino viewport after Slice: a part with the spiral toolpath baked, skirt loop visible at the base, build-volume box wireframed around it.

What gets baked

Layer	Content	Always baked?
3DP::Spiral Toolpath	Continuous spiral curve (Spiral mode)	Spiral mode only
3DP::Outer Toolpath	Outer wall curve per layer (Layer mode)	Layer mode only
3DP::Bracing Toolpath	Zigzag or sinusoidal rib per layer (see Settings reference)	Layer mode + Bracing
3DP::Skirt	15 mm outward-offset loop from the lowest contour	Always
3DP::Build Volume	Wireframe box of the configured cell envelope	Always
3DP::Print Position	RGB axis cross at world origin	Always

📷 Close-up of a sliced spiral with the layer striations visible.

Slice modes

• Spiral Slice — vase mode. One continuous spiral between horizontal contours; no Z-seam.
• Layer Slice — discrete planar layer contours. With Outer Wall Bracing enabled, each layer also gets a structural rib anchored to an inward-offset projection. The rib is either a zigzag (sharp triangle wave, default) or a sinusoidal cosine wave (smoother robot motion, no corner reversals) — toggle in Settings. Wall-contact points sit half a bead width inboard of the contour centerline so the bracing bead's outer edge tangentially meets the outer-wall bead at the contour centerline ("french kiss" overlap — Issue #11) for solid structural bonding. Robot prints outer wall → bracing → next layer.

Bracing only runs on ruled / extrudable geometry (cylinders, prisms, cones, planar extrusions). Free-form Breps are rejected up front — the per-layer seam-align algorithm wanders on organic shapes and produces a twisted unprintable structure.

📷 Side-by-side comparison: Spiral mode vs Layer + Bracing mode on the same cylinder, showing the different toolpath styles.

Build-volume safety

Two checks fire on every slice:

1. Pre-slice — geometry bbox vs configured build volume. If the part overflows, a cancellable popup asks whether to continue anyway. (Useful when you've turned shrinkage up and the scaled part briefly overflows but you know the print will still fit.)
2. Post-slice — full toolpath bbox (skirt + base + part frames) vs build volume. If overflow is detected here, the plugin arms an internal flag that hard-blocks 3. Send to RoboDK. You can still inspect the bake, but you can't send it.

📷 Popup screenshot showing the post-slice "robot would crash" warning.

The block is released by re-slicing successfully — typically by lowering shrinkage %, moving the part, or expanding the build volume.

Skirt — always on

Every part begins with a 15 mm outward skirt loop printed before the part itself, derived from the lowest contour. This:

• Primes the extruder (initial feed of clay before the part starts)
• Gives a visible alignment reference on the build plate
• Closes the loop without a Z lift before transitioning into the part

The skirt is concatenated with the part toolpath into a single curve sent to RoboDK — one approach at the start, one retract at the end, no intermediate Z lift.

Base layers (optional)

If Base → EnableBase is on, the plugin prepends N flat layer contours below the part body — useful for parts with narrow footprints that need extra adhesion / mass at the build plate. The part geometry shifts up by N × LayerHeight so the part itself starts above the base.

Next: 4. Analyze.