Fusion Keychain Project Sheet
Fusion 360 • CAD & Rapid Prototyping Imperial Units (Inches)
FDM 3D Print Lab
Keychain Forge Project Sheet
Design, model, and manufacture a functional, ergonomic everyday-carry keychain.
Tolerances: ± 0.008 in
Designer:
Period / Section:
Date:
Design Mission
Create a personalized keychain in Autodesk Fusion 360 using fully constrained sketches set to imperial units (inches), parametric features, and smooth transitions. Your model must fit a standard split key ring, withstand pocket carry, and print cleanly on an FDM printer without support structures.
Technical & Slicing Constraints (Hard Limits in Inches)
Strict Verification Required
Bounding Envelope
Max 4 × 3 in
Total Thickness: 0.14 - 0.20 in (~5/32 in).
Keyring Hole
Ø 0.187 - 0.220 in
Wall offset: ≥ 0.125 in (1/8 in) solid loop.
Relief & Text
0.035 - 0.050 in
Emboss/deboss depth; stroke ≥ 0.050 in.
Print Efficiency
≤ 25 Minutes
0 Supports; oriented flat on print bed.
Ideation & Dimensioned Concept Sketches (Inches)
Sketch 2 distinct design ideas. Annotate overall dimensions (inches) and mark the keyring hole center.
Scale 1:1 Recommended
Concept Option A: Top-down profile & dimensions
Est. Dimensions: ____ × ____ in Style: [ ] Geometric [ ] Organic
Concept Option B: Alternative shape or text layout
Est. Dimensions: ____ × ____ in Selected for CAD: [ ] A [ ] B
Fusion 360 CAD Milestone Checklist
Verify each step in your parametric timeline
1. Unit Setup & Constrained Sketch
Set Document Settings to Inches (in). Fully constrain lines with dimensions & relations until black.
2. Base Solid Extrude
Extrude base plate between 0.14 in and 0.18 in. Verify as a single watertight solid body.
3. Keyhole Clearance Bore
Bore ≥ 0.187 in (3/16 in) hole with ≥ 0.125 in (1/8 in) outer wall thickness to prevent snapping.
4. Relief Feature (Text / SVG)
Project text or icon; extrude 0.040 in (embossed positive or debossed cut into top face).
5. Edge Fillets & Chamfers
Apply 0.050 - 0.075 in fillets to all outer corners and edges for pocket comfort and stress relief.
6. Mesh Export (.STL / .3MF)
Right-click body > Save As Mesh > Refinement: High > Ensure export units match slicer setup.
Autodesk Fusion 360 • Engineering Design • Student Project Packet Page 1 of 2
Phase 2 • Verification & Analysis
Slicing, Inspection & Reflection
Student Name:
PRINT LOG
Pre-Print Slicer Verification (Cura / PrusaSlicer / Bambu Studio)
Check Before Printing
Layer Height 0.008 in (0.20 mm standard)
Infill Density 20% - 30% Gyroid / Grid pattern
Perimeter Walls 3 Solid Walls (≥ 0.048 in shell)
Supports None (0%) Overhangs ≤ 45°
Sliced Print Time:
min
Filament Used:
g / oz
Bed Adhesion: [ ] Skirt [ ] Brim
Physical Caliper Inspection (Decimal Inches)
Measure printed part with dial/digital caliper
Length & Width
CAD Spec: ____ × ____ in
Actual Measured: ____ × ____ in
Thickness (Z-Axis)
CAD Spec: ____ in
Actual Measured: ____ in
Hole & Ring Fit
Inner Ø: ____ in
Ring loops cleanly: [ ] Pass [ ] Fail
Surface: [ ] Smooth first layer (no elephant foot) Legibility: [ ] Text / logo is sharp and legible Durability: [ ] Loop shows no delamination flex
Engineering Reflection & Design Iteration
1. CAD Timeline & Constraint Challenges: Describe one specific obstacle you faced in Fusion 360 (e.g., setting inch units, fully constraining geometry, broken timeline dependencies, or fillet failures) and how you diagnosed and resolved it.
2. Tolerance & Manufacturing Variance: Compare your caliper measurements (in inches) to your CAD model. Did your print shrink, expand, or warp? What additive manufacturing factors (nozzle diameter, extrusion width, thermal contraction) caused these variances?
3. Keychain 2.0 (Design Iteration for Mass Production): If you had to batch-produce 250 copies of your design, identify two specific changes you would make to either decrease print time or increase mechanical durability in pocket carry.
Assessment Rubric Summary
Total Score: ____ / 16 Points
1. Constraints (4 pts)
Envelope, hole Ø, and thickness match inch specs.
Score: ___ / 4
2. CAD Modeling (4 pts)
Fully constrained sketches & clean timeline.
Score: ___ / 4
3. Printability (4 pts)
Zero supports, layer adhesion & ring clearance.
Score: ___ / 4
4. Reflection (4 pts)
Deep analysis of tolerances, failures & iteration.
Score: ___ / 4
Autodesk Fusion 360 • Engineering Design • Student Project Packet Page 2 of 2
