cdsl-cad/backend/agent/skills/cad-engine/references/part-skills/source/atomic/pattern-holes-from-datum.atomic.md

Pattern Holes From Datum Atomic Skill

When to use

• A model has repeated holes or repeated cut features that should be controlled by pitch, angle, symmetry, or a construction datum.
• The design intent is a hole row, hole grid, mirrored pair, circular bolt circle, or repeated mounting pattern.

Do not use when

• There is only one custom non-repeated hole.
• Holes are intentionally irregular or individually dimensioned.
• The feature is decorative and not constrained by functional layout.

Recognition features

• Multiple holes with equal spacing, equal angular spacing, or mirrored positions.
• SolidWorks evidence such as LinearPattern, CircularPattern, MirrorPattern, or repeated HoleWzd features.
• Datum clues such as centerlines, edge offsets, pitch dimensions, central axis, or symmetry planes.

Core invariants

• Build one correct seed hole or seed cut feature first.
• Constrain the seed from a datum: edge offset, centerline, pitch circle, or axis.
• Pattern the feature/cut, not only sketch circles.
• Choose pattern type from geometry: linear for rows/grids, circular for flange bolt circles, mirror for symmetric pairs.
• Keep the pattern editable by count, pitch, angle, and axis rather than hard-coded coordinates.

Parameter roles

• seed_position defines the first hole from the datum.
• pitch defines linear spacing.
• count defines number of repeated instances.
• pattern_direction defines row/grid direction.
• pattern_axis defines circular pattern axis.
• total_angle is usually 360 degrees for full bolt circles.
• mirror_plane defines symmetric duplication.

Construction sequence

1. Define the datum: edge offset, centerline, symmetry plane, or central axis.
2. Create and validate one seed hole or cut feature.
3. Select linear, circular, or mirror pattern based on the part family and layout.
4. Pattern the feature with explicit count and spacing/angle.
5. Add shared counterbore/countersink/thread detail before patterning when all instances match.
6. Verify clearance to edges, central bores, slots, and neighboring holes.

Common failures

• Duplicating sketch circles without actual cuts.
• Using linear pattern for a flange bolt circle.
• Using circular pattern for rectangular plate holes.
• Patterning counterbore circles without patterning the underlying through hole.
• Missing the datum so later size changes break alignment.

Evidence summary

• Current library evidence: 58 reviewed SCAD58 models with repeated hole patterns.
• Latest run evidence: accepted insights for linear repeated holes, mirror symmetry, symmetric hole placement, circular bolt patterns, and datum-driven construction geometry.
• Frequent operations in the latest run: HoleWzd, Cut, LinearPattern, MirrorPattern, CircularPattern.
• Source: CAD-SkillX offline review of SCAD58 descriptions, STEP summaries, and SolidWorks feature evidence.

Retrieval metadata

Triggers:

• hole pattern
• pattern holes from datum
• repeated holes
• symmetric holes

Secondary triggers:

• linear pattern
• circular pattern
• mirror pattern
• bolt holes
• hole grid

Operation triggers:

• pattern cut feature
• linear pattern
• circular pattern
• mirror

Exclusions:

• single custom hole
• decorative circles
• irregular holes