Button Head vs. Truss Head
Comparing 2 standards across 11 specifications. 11 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.
Truss Head screws (also known as Mushroom Head / Extra-Wide Pan) feature an extra-wide, low-profile domed head with a large-diameter flat bearing underside. Designed to span large clearance holes and clamp thin sheet metal without tearing or requiring external flat washers, they are widely used in metal building framing and cabinet door hardware.
Specification Comparison Table
11 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Specifications
|
ISO 7380-1 / ASME B18.3 | ASME B18.6.3 / IFI Standards |
|
Primary Applications
|
3D printer motion carriages, motorcycle fairings, electronics rack enclosures | Thin sheet metal ducting, electrical junction boxes, cabinet drawer slide tracks |
|
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 Diameter Ratio
|
— | Extra-wide base (D_k ≈ 2.2× to 2.5× shank diameter) |
|
Head Height Profile
|
— | Ultra-low curved dome (flatter and wider than standard pan head) |
|
Bearing Surface
|
— | 100% Flat horizontal bearing surface with maximum surface contact area |
|
Common Drive Recesses
|
— | Phillips (PH2), Square (Robertson #2), Combo, Slotted |