Chamfers, tapers, or bevels added to mating part edges to guide components into position during assembly, compensating for misalignment and easing insertion.
A lead-in chamfer on a hole or shaft reduces the required alignment precision during assembly. Standard chamfer angle: 15–45°. Chamfer depth = 0.5–1× tolerance of mating feature. For press-fit pins: chamfer the pin tip at 30–45°. For hex pockets: add 0.5 mm × 45° chamfer at entry. DfAM extends this to consider robotic and manual assembly ergonomics.
Always add ≥ 0.5 mm × 45° chamfer to hole entries for bolts, pins, and inserts in FDM parts. Add chamfer to shaft/pin tips. For complex assemblies, add first-article assembly instructions noting feature lead-ins. Chamfers also reduce stress concentration at hole edges.
Omitting draft chamfers causes 'jam and rock' assembly: the part must be perfectly aligned before insertion, causing damage to fragile FDM surfaces. Interior chamfers on small holes (<5 mm) may not print cleanly in FDM: verify with a test print.
Related terms: Assembly Clearance, DfAM (Design for Additive Manufacturing), Hole Sizing for 3D Printing, Press Fit
| Field | engineering |
|---|---|
| Also called | assembly draft, assembly chamfer, lead-in chamfer |
| Source | EDi Brain: rules-core |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert