Button Head vs. Countersunk
Comparing 2 standards across 12 specifications. 12 key differences identified.
Button Head Cap Screws (BHCS, standardized under ISO 7380) feature a low-profile rounded dome with a wide load-bearing base and an internal hex or Torx drive recess. Designed for applications requiring a smooth, snag-free finish and low vertical clearance, they provide clean aesthetics on exposed consumer products, 3D printers, and automotive interiors.
Flat Head (Countersunk / CSK, standardized under ISO 7046 and DIN 965) screws feature a flat top face and a conical tapered underside (90° in ISO Metric, 82° in US Imperial, 100° in Aerospace). Designed to seat inside a matching chamfered hole, the head sits 100% flush with or slightly below the surface of the joined material.
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Specifications
|
ISO 7380-1 / ASME B18.3 | ISO 7046 / DIN 965 / ASME B18.6.3 |
|
Primary Applications
|
3D printer motion carriages, motorcycle fairings, electronics rack enclosures | Woodworking, door hinges, machine slides, aircraft aerodynamic skin |
|
Head Profile
|
Low-profile smooth domed contour | — |
|
Bearing Base Diameter
|
Extra-wide circular bearing base (approx. 1.75 × shank diameter) | — |
|
Drive Recess
|
Internal Hexagon (Allen) or Hexalobular (Torx / ISO 7380-2) | — |
|
Torque Rating
|
Reduced torque rating compared to DIN 912 socket caps (due to shallower socket depth) | — |
|
Flanged Variant
|
ISO 7380-2 (Button head with integrated wide flange collar) | — |
|
Head Top Profile
|
— | 100% Flat top face |
|
Countersink Angle (ISO Metric / DIN)
|
— | 90 degrees |
|
Countersink Angle (US Imperial / ASME)
|
— | 82 degrees |
|
Countersink Angle (Aerospace / NAS)
|
— | 100 degrees (for thin structural aircraft skins) |
|
Length Measurement Rule
|
— | Overall Length (Measured from top of head to screw tip) |