scenario-blender-hard-surface

Blender hard surface

Expert hard surface is controlled light on edges: every edge catches a highlight from a bevel or a support loop, flat faces read perfectly flat, and cuts stay editable until the design is settled. The experts disagree on method (n-gons and booleans vs quad cages and subdivision), not on the checks: order of operations, cutter hygiene, planar faces, a shiny matcap orbit. The agent builds the stack with the toolkit and lets the measurable gates find what a human finds by orbiting. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-blender-expert (execution channel, review loop, 5.2 API changes). Toolkit: scripts/bx_hardsurface.py (import sys; sys.path.append("<skills>/scenario-blender-hard-surface/scripts"); import bx_hardsurface as HS), world-space meters, stock Blender only.

Stance (the expert delta)

• Cut first, bevel after, normals last. Booleans above the angle-limited micro bevel, Weighted Normal at the very bottom, a late Mirror above it (Ryuu [00:26:26], [00:28:37]; du Mont [00:19:46]). In 5.2 a pinned modifier keeps its relative order inside the pinned group and new modifiers land above it, so pin bottom-up: HS.order_stack does it and HS.add_boolean always lands above the tail (verified).
• Two bevels, two jobs (du Mont [00:12:25] to [00:15:15]): a weight-limited design bevel (8 to 12 segments) on chosen silhouette edges before the cuts, and an angle-limited micro bevel (30 degrees, Harden Normals, Miter Outer Arc) after every cut, because no real edge is perfectly sharp (Gambrell, du Mont, Ryuu).
• A bevel that shrinks after a boolean is geometry, not a setting (du Mont [00:20:18], [00:30:20]). Move the cutter well away from target edges or make it exactly coincident; keep Clamp Overlap on. Clamp Overlap limits the bevel over the whole object: a slot running 0.7 degrees off a facet edge (clamp ratio 3.8) wiped out the 3 mm bevel on a port elsewhere on the part [verified in 5.2.1]. HS.clamp_culprits names the cut.
• Every wall, step, gap and rounding facet must be wider than 2x the micro bevel width [added, verified]: a 1 mm pocket floor, a 1.5 mm wall, a 2 mm groove with 1.5 mm bevels (a 3.1 mm one was clean) and a slot rounded in 30-degree facets all clamped the whole object's bevel.
• If Harden Normals or Weighted Normal changes nothing, the face is not flat (Gambrell [00:01:06]). Flatten it; more normal modifiers will not help.
• Pick the school by the part, not by taste. Planar machined parts with many cuts: n-gons + booleans + bevel + custom normals, about a quarter of the time and stays editable (Gambrell [00:18:01]). Continuous curvature, non-uniform roundness, a sculpt or bake high: quad cage + subdivision (rileyb3d, PzThree). Sharpen subD edges with support loops, not creases: 36,800 vs 3,600 triangles at equal quality (Lampel [00:05:28]).
• EXACT is the solver. Gambrell's 2021 "switch to Fast" predates 5.x: Float left 16 non-manifold edges on a coplanar cutter where Exact and Manifold were clean [verified]. When Exact misbehaves the operand is broken (Ryuu [00:15:13]): an open cutter gave Exact 19 non-manifold edges and Manifold silently skipped the cut [verified].
• Judge in a shiny matcap and close up on every cut (Gambrell [00:00:33], rileyb3d [00:06:32]). Whole-object sheets hide smears and shrunken bevels.