Opt-in reviewed CAD split plans and dowel connectors

Print Buddy never auto-cuts a single connected solid mesh when arranging parts (python3 -m print_buddy.core.model_job layout). When an oversized single mesh cannot or should not be printed intact, python3 -m print_buddy.core.model_job cad-split provides an opt-in, schema-validated CAD split workflow with alignment/connector bores and printable chamfered dowels.

Safety and structural boundaries

1. Intact diagonal print first: Before cutting any mesh, cad-split checks whether the intact mesh fits the nominal bed under a Z rotation (such as 45 degrees on a 220 x 220 x 220 mm AD5X bed) and exports the intact rotated STL alongside the split artifacts.
2. Reviewed split plans only: Every split requires an explicit --plan preset (rack_adapter_10to19, macmini_mount_a1347) or a reviewed JSON split-plan file. Unreviewed arbitrary planar cuts are rejected.
3. Volume conservation and topology checks: When --execute runs OpenSCAD CSG booleans, Print Buddy verifies that both resulting halves are watertight, 1-shell solids and that the removed volume equals the theoretical cylindrical bore volume within tolerance (whole_volume - (left_volume + right_volume) == expected_bore_volume).
4. Honest status reporting: split_validation.json records the 5-stage status_ladder (geometry_inspected, geometry_nominal_fit, slicer_capacity_verified, gcode_sliced_and_guarded, physical_print_tested) and never marks slicer or physical print stages as passed during offline CAD preparation.
5. No structural load rating: Socket bores and printed/metal dowels locate and bond parts; no structural load rating has been performed.

Built-in reviewed presets

Preset ID	Target geometry	Split plane	Connectors & clearances
rack_adapter_10to19	10-to-19-inch rack adapter (245.0 x 44.5 x 20.0 mm, 1 shell)	X = 0.0 mm	4 blind bores (Ø5.40 mm x 16.5 mm per side at Y = ±12 mm, Z = 6, 14 mm) + 4 printable chamfered dowels (Ø5.00 mm x 30.5 mm, 0.20 mm radial clearance, 2.5 mm length relief)
macmini_mount_a1347	Mac Mini A1347 mount (254.0 x 44.625 x 183.4078 mm, 2 overlapping shells)	X = 0.0 mm (shell-wise cut + union)	2 front M3 pin bores (Ø3.35 mm x 11.5 mm per side at Y = -18.7 mm, Z = 4.5, 11.5 mm) + 1 rear filament guide bore (Ø2.15 mm x 11.5 mm per side at Y = 20.7 mm, Z = 5.5 mm)

CLI usage

Prepare the intact rotated STL, printable chamfered dowels, OpenSCAD CSG script, and split_validation.json without invoking external CAD binaries:

python3 -m print_buddy.core.model_job cad-split \
  path/to/10to19_adapter_with_ears.stl \
  --plan rack_adapter_10to19 \
  --outdir ./rack_split_out

Also execute OpenSCAD to render the boolean split halves and verify post-boolean volume conservation:

python3 -m print_buddy.core.model_job cad-split \
  path/to/10to19_adapter_with_ears.stl \
  --plan rack_adapter_10to19 \
  --outdir ./rack_split_out \
  --execute