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Module 2 — Parts & Subassemblies

Objective: build accurate models quickly and check motion/clearance.

Prereqs: Workspace with MKCAD and templates.

Steps

  • Import COTS from MKCAD; model custom parts with correct mass/material.
  • Constrain motion; check clearances and interferences through full travel.
  • Add simplified versions for performance if needed.
  • Add mates to reflect real constraints (slots, bearings) and check for over-constraints.
  • Run exploded views and section views to confirm stackups and fastener access.

Deliverables

  • Subsystem assembly with motion verified and no interferences.
  • List of critical dimensions and datum references for drawings.

Resources

  • Onshape Learning Center: learn.onshape.com

Instructions (numbered)

  1. Import COTS from MKCAD; model custom parts with correct materials/mass.
  2. Apply mates to reflect real constraints; avoid over-constraining.
  3. Check motion through full travel; run interference/clearance checks.
  4. Create exploded/section views to verify stackups and fastener access.
  5. Make simplified configs if performance lags.
  6. Capture critical dimensions and datums for drawings.

Example

  • Intake assembly: MKCAD rollers, custom plates with correct material; mate limits set; section view confirms bearing stack; simplified config without threads for performance.

Best practices

  • Use mate limits to reflect real travel; avoid unnecessary detail in early stages.
  • Check tool access for fasteners in CAD, not in the pit.
  • Keep simplified versions for large assemblies.

Common mistakes

  • Over-constraining mates → rebuild errors.
  • Missing clearances/interferences until late.
  • No tool access; ignoring thread engagement.

Checklist

  • COTS imported; materials set
  • Mates applied and not over-constrained
  • Motion and interference checked
  • Exploded/section views reviewed
  • Simplified config (if needed)
  • Critical dims/datums captured

Recommended tools

  • Onshape Interference/Measure, exploded views, section views, mate limit settings.

Sample log (template)

  • Date:
  • Assembly changes:
  • Checks run:
  • Issues/fixes:

Photos/diagrams

  • [Placeholder: exploded view and section view screenshots]