Rhino 3D Tip: Clean, reliable hatch boundaries from Make2D

Clean, reliable hatch boundaries start with how you run Make2D and how you clean its output.

Workflow overview:

• Model prep:
  • Set Units and tolerances appropriately (tight absolute tolerance reduces tiny gaps).
  • Organize by layers you want to control in 2D (e.g., “Sections,” “Hidden,” “Hatchable”).
  • Freeze/hide unneeded geometry before Make2D to minimize overlaps.
• Run Make2D with intent:
  • Choose Projection = View (for presentation) or CPlane/World for orthographic drawings.
  • Disable Tangent Edges if they clutter regions you plan to hatch.
  • Enable Maintain source layers and Group output for easy selection/management.
  • Separate visible vs hidden lines; only hatch from visible outlines.

Post-process for clean boundaries:

• Flatten certainty:
  • Use ProjectToCPlane (DeleteInput=Yes) or SetPt (Z only) to guarantee all curves are coplanar.
• Remove duplicates and micro-segments:
  • SelDup then Delete to kill stacked lines.
  • SimplifyCrv with a tolerance smaller than your drawing precision; then Merge and Join to consolidate collinear edges.
  • SelSmall to find slivers; consider deleting or combining as needed.
• Close gaps and build regions:
  • CurveBoolean is your friend: click inside the areas you intend to hatch, set DeleteInput=Yes to output clean, single-loop boundaries.
  • Where gaps persist, use Extend, FilletCorners, or CloseCrv to seal them.
  • Check with SelOpenCrv to ensure only closed loops remain for hatching.

Hatching best practices:

• Use Hatch on closed, planar curves only. Self-intersections or overlaps will fail.
• Adopt named Hatch patterns and Annotation scales so drawings stay consistent across layouts.
• Place hatches on dedicated hatch layers (by material or cut type) for quick visibility and print control.

Quality control:

• Toggle wireframe/technical display to spot tiny leaks in boundaries.
• Use What on suspect curves to confirm “Closed curve = Yes.”
• If Make2D output is overly fragmented, slightly relax tolerance in SimplifyCrv and retry CurveBoolean.

Automation macro (starter idea):

• _-Make2D _Projection=View _TangentEdges=No _HiddenLines=No _MaintainSourceLayers=Yes _GroupOutput=Yes _Enter
  _SelDup _Delete
  _SimplifyCrv _Tolerance=0.01 _Enter
  _Join
  _CurveBoolean _DeleteInput=Yes
  _SelClosedCrv _Hatch _Pattern=Solid _Scale=1 _Enter

Grasshopper option (for repetitive drawings):

• Make2D component → RegionUnion → Boundary Surfaces → Bake → Hatch. This pipeline reduces manual cleanup and is ideal for standardized outputs.

Pro tips:

• Turn off hidden lines during hatching; add them back later on a separate print layer.
• Use Layer States to switch between “Hatch Edit” and “Final Plot” configurations.
• Consider Solid hatch for sections and patterned hatches for materials; keep scales consistent across layouts.

Need Rhino licenses, plug-ins, or expert advice? Explore Rhino at NOVEDGE and follow NOVEDGE for professional CAD/CAM tips and offers.

You can find all the Rhino products on the NOVEDGE web site at this page.