Key principles.
Inch standard
Standard inch flathead screws. ANSI B18.2.
Metric standard
Standard metric flathead screws. ISO 7045.
Aerospace
Aerospace flush rivets. NAS standard.
Specialty
Specialty applications. Less common.
Per fastener
Countersink diameter slightly larger than head diameter.
Flush mounting
Depth places head flush with surface.
FAQ
82° inch (most common). 90° metric. 100° aerospace. 120° specialty. Verify per fastener.
±0.05 mm typical countersink diameter and angle.
Note "82° CSK Ø10.5" for 82° countersink, 10.5 mm diameter at top surface.
Drill-countersink (combo) tools available. One operation, drill + chamfer.
Standard milled Ra 1.6 µm. Polish for cosmetic. Per drawing spec.
Standard countersink no premium. Custom angles slight cost. Specialty tools may add.
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