Final Build: Gearbox — RoboCAD Academy

Two-Stage Spur Gearbox — complete assembly with housing, shafts, and gear train (9:1 total ratio).

Planetary Gear Set — sun, planets, carrier, and ring gear in a compact coaxial arrangement.

1 Experience

2 Reflect

3 Theorize

4 Apply

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Quick Review Opportunity

Revisit

Putting It All Together

Time to apply everything you've learned to build a real-world component: a gearbox.

Part Design: The Gears

Sketch involute profiles for the sun, planet, and ring gears. Use Revolve and Extrude, maintaining a constant module and pressure angle across all gears.

Part Design: The Carrier

Design a carrier for the planet gears with axle holes using a transition fit to hold shafts without binding.

The Assembly Workflow

In a new assembly, ground the ring gear, apply Revolute joints for the sun and carrier, then pin planets to the carrier axles with rigid joints.

Design for Manufacturing Checklist

Before exporting to STL or STEP, verify:

Fillets are applied to the internal corners of the carrier plates.
The clearance between the gear teeth is at least 0.15mm (for FDM 3D printing).
Sufficient wall thickness around press-fit bearings.

Stage 2 Pause and Reflect

Looking back at all 15 modules, which concept changed your understanding of CAD the most?

What would you do differently if you started this gearbox project from scratch?

✓ Your reflections are saved automatically

Stage 4 Apply What You Learned

Complete the gearbox design by applying every concept from the course.

Verify all gear ratios match the required output speed and torque
Check that every part is fully constrained in the assembly
Run interference detection to find any collisions
Create a drawing package with dimensions, tolerances, and BOM
Evaluate manufacturability: can every part actually be built?
Prepare a presentation render showing the assembled gearbox

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Reference Assembly: T-Slot Frame

This example assembly was generated by AICAD AssemblyForge, a companion tool that creates parametric 3D models from text descriptions using CadQuery. It demonstrates exactly the kind of assembly workflow you're learning in this module.

Parts List

Part	File	Qty	Dimensions (mm)
20x20 T-Slot Extrusion	`extrusion_2020_160mm.step`	4	160 × 20 × 20
L-Shaped Corner Bracket	`corner_bracket.step`	4	40 × 20 × 4

Assembly Steps

Insert two M5 T-nuts into the end slots of each extrusion (8 total).
Lay out four extrusions in a square, butting ends together for a 200×200 mm outer dimension.
Place a corner bracket at each joint, aligning bolt holes over T-nut positions.
Insert 3 mm dowel pins into corner alignment holes.
Thread M5×8 bolts through bracket holes into T-nuts and torque to 4 Nm.

Hardware needed: 8× M5×8 Button Head Cap Screws • 8× M5 T-Nuts (drop-in) • 4× 3×5 mm Dowel Pins

This assembly was auto-generated from the prompt: "a simple 80/20 T-slot frame, 200x200mm square using 2020 extrusions with corner brackets". The AssemblyForge pipeline enriched the prompt, generated CadQuery scripts, validated mesh geometry, and produced STEP files ready for 3D printing.

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