Extruder-off travel mode for disjoint infill segments

[CyberCraftLab]

Migrated from GitLab issue bac39641/ccl_clay3dp#19 — created 2026-04-25T18:33:05.628+02:00 by Christophe Barlieb.

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Context

Issue #10 introduced multi-segment infill polylines for non-convex contours. The snake stitching breaks the polyline whenever a connector would cross outside the contour, so the bake visualization is clean.

But during print, the robot still travels at op-speed between disjoint segments with the extruder on, laying a short bead during cross-segment hops. Not visible in the bake (only toolpath polylines are baked) but it WILL show on the printed part as unwanted material across concavities.

Goal

A travel mode that, between disjoint print blocks:

1. Issues extruder-off (S1 — minimum valid value, per cell convention)
2. Slow Z-hop up at F600 (matches existing skirt plunge/retract convention)
3. Travels in XY at travel-speed (faster than op-speed)
4. Slow Z-hop down at F600
5. Resumes extruder (S<spindle>) before the next print frame

Scope

• Add a travel bool flag to the per-frame JSON (RoboDK/FrameSerializer.cs)
• Mark frames between disjoint base-infill polylines as travel=true (BaseBuilder + InfillGenerator)
• Update PostProcessor/KUKA_CNC_2_1_*.py to emit S1 / Z-hop / S<spindle> on travel frames
• New settings: Z-hop height (mm, default ~2), travel speed (mm/s, default ~50)
• Decision needed during implementation: skirt → base → part transitions stay continuous (per base for "vase" like object (user can select) #10 design); only inter-infill-segment hops get travel mode

Acceptance

• Print a teddy-bear-silhouette base
• No material laid between disjoint regions during infill travels
• Skirt-to-base and base-to-part transitions unchanged (still continuous bead)

Related

• Follows up base for "vase" like object (user can select) #10 (multi-layer base feature)
• Memory note: S1 = extruder off (min valid), slow Z plunge/retract at F600

[CyberCraftLab]

Postponed until we upgrade the Stoneflower Board