Head & Drive Type Guide
Fastener Head & Drive Type Guide
Identify screw and bolt head styles, drive types, and their applications. Choose the right head style for flush mounting, high torque, tamper resistance, or general purpose use.
Common Head Styles
| Head Style | Profile | Sits Flush? | Bearing Surface | Typical Applications |
|---|---|---|---|---|
| Hex Head | Tall, 6-sided | No | Large | Structural, machinery, heavy assembly |
| Socket Head (SHCS) | Cylindrical, hex socket | No | Small | Tight spaces, precision machinery, tooling |
| Button Head (BHCS) | Low dome, hex socket | No | Medium | Aesthetics, low-profile, guards/covers |
| Flat Head (FHCS) | Countersunk, 82° | Yes | Tapered | Flush mount, countersunk holes, appearance |
| Pan Head | Slightly rounded, wide | No | Wide | Sheet metal, general purpose, electronics |
| Truss Head | Extra wide, low dome | No | Very wide | Thin materials, prevents pull-through |
| Round Head | Dome shaped | No | Small | Decorative, wood screws, carriage bolts |
| Hex Washer Head | Hex + built-in washer | No | Very wide | Self-drilling, roofing, sheet metal |
| Bugle Head | Countersunk, curved | Yes | Tapered | Drywall screws — won't tear paper |
| Fillister Head | Tall cylindrical | No | Small | Deep slot, counterbored holes, machinery |
| Binding Head | Wide, undercut | No | Wide | Electrical connections, binding posts |
Drive Types
| Drive Type | Torque Capacity | Cam-Out Resistance | Tamper Resistant | Notes |
|---|---|---|---|---|
| Phillips (#) | Medium | Low | No | Most common, designed to cam out at set torque |
| Slotted (-) | Low | Very Low | No | Oldest style, easy to strip, use flat blade driver |
| Hex Socket (Allen) | Very High | Very High | No | Socket head cap screws, set screws, precision |
| Square (Robertson) | High | High | No | Popular in Canada, excellent bit engagement |
| Six-Lobe (Torx®) | Very High | Very High | No | Automotive, electronics, maximum torque transfer |
| Combo (Phil/Slot) | Medium | Low | No | Accepts either Phillips or flat blade |
| Pozidrive (PZ) | High | Medium | No | European standard, looks like Phillips with tick marks |
| Pin Hex | High | High | Yes | Hex socket with center pin, tamper-proof |
| Pin Torx | Very High | Very High | Yes | Six-lobe with center pin, high security |
| One-Way | Install only | N/A | Yes | Can be installed but not removed, permanent |
Countersink Angles
82° (Standard US)
Most common countersink angle for US flat head machine screws and socket flat heads. Standard for industrial applications.
90° (Metric / DIN)
Standard angle for metric flat head screws (DIN 965, ISO 7046). Also used in some wood screws and self-tapping applications.
100° (Aerospace)
Used in aerospace applications (MS24694, NAS1580). Provides wider bearing surface in thin sheet material.
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