Button Head (BHCS)
Direct Answer
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.
Source: ISO 7380-1 / ASME B18.3
Specs
| Standard Specifications | ISO 7380-1 / ASME B18.3 |
| Head Profile | Low-profile smooth domed contour |
| Bearing Base Diameter | Extra-wide circular bearing base (approx. $1.75 \times$ 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) |
| Primary Applications | 3D printer motion carriages, motorcycle fairings, electronics rack enclosures |
Aesthetic and Low-Clearance Benefits
Button head screws eliminate sharp vertical corners. Their smooth, rounded dome prevents clothing from catching on exposed machinery, makes accidental tool impact bounce off harmlessly, and fits into tight spatial gaps where a tall DIN 912 socket cap would collide with moving machine slides.
Shallower Socket Depth Warning
Because the button dome is low-profile, its internal hex socket is shallower than that of a standard socket cap screw. When tightening button head screws into high-strength assemblies, operators must use high-quality, unworn hex keys to prevent stripping the shallow socket.