CAD Level 2 - Part Design & Assembly

Learning Objective

Create complex 3D parts using advanced modeling features (revolve, sweep, loft, patterns), build multi-part assemblies using top-down and bottom-up design methodology with proper mate constraints and interference checking, integrate vendor COTS parts, apply design for manufacturing principles including tolerances and standard fasteners, and generate technical drawings with dimensions and annotations. This level is self-guided and typically takes a couple of months; completing it means you can perform most of the CAD work the team needs day to day.

Prerequisites

• CAD Level 1 - Fundamentals

Primary Resources

• OnShape -- Advanced Part and Surfacing Design
• FRCDesignLib (shared OnShape library of FRC-relevant COTS parts)
• FRCDesign.org -- Assembly Best Practices
• FRCDesign.org -- Design Challenges

Tasks

1. Advanced Part Features

   • Complete OnShape's advanced part modeling learning path
   • Master revolve, sweep, and loft operations
   • Create complex patterns (feature-driven, table-driven)
   • Use multi-body part design techniques
   • Apply configurations for part families
   • Project: Design a custom wheel or roller with multiple configurations
     • Use advanced features: revolve, circular patterns, configurations
   • Assessment: Design a custom FRC bumper bracket with 3 size configurations

2. Vendor & COTS Parts

   • Import and use COTS components from FRCDesignLib
   • Import vendor part files (WCP, REV, AndyMark, McMaster-Carr) into an assembly
   • Understand when to use a COTS part versus designing a custom one

3. Assembly Creation & Management

   • Complete OnShape's assemblies learning path (all modules)
   • Follow FRCDesign.org's Assembly Best Practices
   • Understand top-down versus bottom-up assembly design methodology and when to use each
   • Insert parts and sub-assemblies into a main assembly
   • Apply mate constraints (fastened, revolute, cylindrical, planar, ball)
   • Create assembly configurations for different robot states
   • Check for interferences using OnShape collision detection
   • Major Project: Build a complete FRC drivetrain assembly
     • Include: chassis, wheels, motors, gearboxes, chain/belt drives
     • Demonstrate proper mate relationships and configurations
   • Assessment: Assembly functions properly with no interferences, all DOF controlled

4. Design for Manufacturing (DFM)

   • Study OnShape's sheet metal and weldments features for FRC applications
   • Apply appropriate tolerances using OnShape's tolerance analysis tools
   • Design parts considering FRC manufacturing constraints (waterjet, 3D printing, machining)
   • Integrate standard FRC fasteners into a design
   • Integration Project: Redesign the Level 1 roller for actual manufacturing
     • Include: proper tolerances, fastener selection, material specifications
     • Consider waterjet cutting and 3D printed components
   • Assessment: Manufacturing review with mentor/machinist approval

5. Technical Documentation

   • Complete OnShape's drawings learning path
   • Create dimensioned drawings with basic GD&T
   • Add section views, detail views, and exploded views
   • Generate an automated Bill of Materials (BOM) from an assembly
   • Include material specifications and finish callouts
   • Documentation Project: Complete a drawing package for the drivetrain assembly
     • Assembly drawing, individual part drawings, BOM, assembly instructions
   • Assessment: Drawing package review for completeness and clarity

Level 2 Completion Requirements

• Complete OnShape's assemblies and drawings learning paths
• Submit a complete drivetrain assembly with a full documentation package
• Mentor approval of DFM principles applied to the redesigned roller
• Peer teaching demonstration to a Level 1 student

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