Onshape Featured Case: One Bracket Thickness Change
A step-by-step examination of how a minor 0.5 mm dimensional adjustment propagates across parametric parts, top-level assemblies, linked drawings, and active bill-of-materials structures.
Structural Flange: 2.0 mm → 2.5 mm
Step 1: Part Studio Feature Tree Recalculation
When the bracket thickness parameter is modified from 2.0 mm to 2.5 mm in the primary Extrude feature, internal bend reliefs and mounting clearance holes regenerate automatically. Feature dependencies must be verified to prevent inverted sketch constraints.
- Sheet Metal Bend Allowance: K-factor formulas adjust total blank size calculation.
- Weight Delta: Mass property update from 312 g to 384 g.
- Clearance Check: Internal bend radius remains constant at R 2.0 mm, slightly shifting inner relief lines.
Step 2: Sub-Assembly Mate & Clearance Shift
In the chassis sub-assembly, the planar mate referencing the outer face of the bracket offsets adjacent mounting rails by exactly 0.5 mm. Fastener alignment holes must maintain nominal axial tolerances.
- Mate Connectors: Planar and Fastened mates resolve without broken kinematic degrees of freedom.
- Interference Alert: 0.5 mm clash detected against adjacent sheet metal enclosure shroud prior to mate adjustment.
- Resolution: Enclosure clearance cutout extended by 1.0 mm to maintain safety gap.
Step 3: Fastener Stack & Grip Length Validation
Increased bracket wall thickness consumes screw thread engagement. The previous M4x10 socket head cap screw no longer satisfies the 1.5x diameter thread engagement rule inside the captive nut plate.
- Old Grip Length: 6.0 mm stack allowed 4.0 mm engagement with M4x10 fastener (insufficient).
- Standard Part Swap: Fastener upgraded to ISO 4762 M4x12 Grade 8.8 (P/N 912-M4-12).
- Engagement Verified: 5.5 mm thread engagement achieved in mating frame.
Step 4: Drawing Annotation & Dimension Updates
The 2D manufacturing drawing (DWG-408-01) displays the updated flange dimension. Flag notes and section views automatically sync with the 3D model revision, highlighting affected datum callouts.
- Associative Dimensions: Thickness dimension reflects 2.50 ±0.08 mm.
- Bending Table: Updated flat pattern dimensions synced with sheet metal DXF export configuration.
- Revision Block: Automated entry created with revision index bump to Rev B.
Step 5: Bill of Materials (BOM) Real-Time Alignment
The multi-level BOM table updates automatically. Raw material consumption fields adjust to sheet stock specifications, and the fastener entry reflects the new part number across all parent assemblies.
- Item Line 04: 408-BRK-01 description updated to "Bracket, 2.5mm AL5052-H32".
- Item Line 12: Swapped fastener from 912-M4-10 (Qty: 4) to 912-M4-12 (Qty: 4).
- ERP Sync readiness: Metadata properties formatted for enterprise synchronization.
Step 6: Where-Used Query & Dependency Tree
Running a Where-Used query identifies every assembly and drawing referencing P/N 408-BRK-01 across workspace branches, isolating secondary project variants that utilize the same component.
- Primary Assembly: ASM-100 Main Chassis Enclosure (In-progress update).
- Secondary Variant: ASM-200 Outdoor Ruggedized Module (Requires engineering review).
- Branch Isolation: Changes preserved in branch `feature/heavy-duty-mount` prior to merge.
Step 7: Release Package & Engineering Change Order
The complete package—bracket, fastener upgrade, revised assembly mates, and updated 2D drawing—is assembled into a unified Release Candidate with automated approval workflows.
- Release Candidate: CR-2026-088 generated with linked item revisions.
- Approver Workflow: Assigned to Lead Mechanical Engineer and Quality Assurance.
- Historical Audit Trail: Immutable version snapshot locked upon final sign-off.
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