87 lines
3.2 KiB
Markdown
87 lines
3.2 KiB
Markdown
# Flange Bolt Circle Functional Skill
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## When to use
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- A flange, circular cover, annular ring, coupling, or flanged sleeve needs fastener holes evenly spaced around a central bore.
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- The request mentions bolt circle, pitch circle, PCD, evenly spaced flange holes, or circular pattern of screws.
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## Do not use when
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- Holes are in a rectangular grid, linear row, or mirrored pair on a plate or bracket.
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- The part has no central axis or central bore.
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- The holes are decorative circular cutouts rather than fastening holes.
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## Recognition features
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- Central bore or hub defines the rotation axis.
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- Bolt holes lie on a pitch circle concentric with the bore.
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- Angular spacing is equal: `360 / bolt_count`.
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- Optional counterbores or countersinks remain concentric with each bolt hole.
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## Core invariants
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- Bolt-circle center, central bore, hub, and outer diameter share the same axis.
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- Create one correct seed hole with the correct diameter and seat type.
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- Circular-pattern the hole feature, not just sketch circles.
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- Keep bolt count, pitch-circle diameter, and start angle explicit.
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- Add counterbore/countersink to the seed hole before patterning when all holes share the same fastener type.
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## Parameter roles
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- `bolt_count` controls number of fastener holes.
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- `bolt_circle_diameter` or `pitch_circle_diameter` controls radial placement.
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- `bolt_hole_diameter` defines clearance or pilot size.
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- `start_angle` controls angular orientation relative to a datum.
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- `counterbore_diameter`, `counterbore_depth`, and `countersink_angle` define fastener seating.
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## Construction sequence
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1. Define the central axis from the flange bore or construction geometry.
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2. Place one seed hole center at radius `bolt_circle_diameter / 2`.
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3. Create the seed hole as a cut, HoleWzd hole, counterbore, or countersink according to the fastener.
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4. Use circular pattern around the central axis for `bolt_count` instances over 360 degrees.
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5. Verify that every patterned hole cuts through the flange and remains inside the outer diameter.
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6. Add final chamfers and fillets after the bolt pattern is complete.
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## Common failures
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- Manually placing each hole and producing uneven angular spacing.
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- Patterning a sketch without cutting material.
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- Using a linear array on a circular flange.
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- Choosing pitch circle too close to the bore or outer edge.
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- Forgetting counterbore/countersink depth for flush fasteners.
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## Evidence summary
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- Current library evidence: 45 reviewed SCAD58 flange-like models.
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- Latest run evidence: accepted atomic and functional insights for circular pattern bolt holes, central bore alignment, and axisymmetric flange bodies.
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- Frequent operations in the latest run: CircularPattern, HoleWzd, Cut, Revolution, Chamfer.
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- Source: CAD-SkillX offline review of SCAD58 descriptions, STEP summaries, and SolidWorks feature evidence.
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## Retrieval metadata
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Triggers:
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- `flange bolt circle`
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- `bolt circle`
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- `pitch circle`
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- `PCD`
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- `circular bolt pattern`
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Secondary triggers:
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- `flange holes`
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- `evenly spaced holes`
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- `central bore`
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- `counterbored flange holes`
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Operation triggers:
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- `circular pattern`
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- `hole wizard`
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- `pattern cut feature`
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- `cut bolt holes`
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Exclusions:
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- `linear hole grid`
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- `mounting plate row`
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- `random holes`
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- `side tab holes`
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