Button Socket Cap Screws
Low-profile domed heads with socket drive.
Button heads where a finished look and snag-free profile matter.
Specifications & technical data.
Button head socket cap screws to ASME B18.3 — the low-profile dome with a hex socket, where a finished look and a snag-free surface matter.
Download our button head cap screw dimensioning table (PDF)
| Nominal Size (Basic Screw Diameter) | A | H | S | J | T | F | L | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Head Diameter | Head Height | Head Side Height (Ref.) | Nominal Hexagon Socket Size | Minimum Key Engagement | Fillet Transition Diameter | Nominal Max. Standard Length | ||||||
| Max. | Min. | Max. | Min. | Max. | Min. | |||||||
| #0 | 0.0600 | 0.114 | 0.104 | 0.032 | 0.026 | 0.010 | – | 0.035 | 0.020 | 0.080 | 0.070 | 0.50 |
| #1 | 0.0730 | 0.139 | 0.129 | 0.039 | 0.033 | 0.010 | – | 0.050 | 0.028 | 0.093 | 0.083 | 0.50 |
| #2 | 0.0860 | 0.164 | 0.154 | 0.046 | 0.038 | 0.010 | – | 0.050 | 0.028 | 0.106 | 0.096 | 0.50 |
| #3 | 0.0990 | 0.188 | 0.176 | 0.052 | 0.044 | 0.010 | 1/16 | 0.062 | 0.035 | 0.119 | 0.109 | 0.50 |
| #4 | 0.1120 | 0.213 | 0.201 | 0.059 | 0.051 | 0.015 | 1/16 | 0.062 | 0.035 | 0.132 | 0.122 | 0.50 |
| #5 | 0.1250 | 0.238 | 0.226 | 0.066 | 0.058 | 0.015 | 5/64 | 0.078 | 0.044 | 0.145 | 0.135 | 0.50 |
| #6 | 0.1380 | 0.262 | 0.250 | 0.073 | 0.063 | 0.015 | 5/64 | 0.078 | 0.044 | 0.158 | 0.148 | 0.63 |
| #8 | 0.1640 | 0.312 | 0.298 | 0.087 | 0.077 | 0.015 | 3/32 | 0.094 | 0.052 | 0.194 | 0.184 | 0.75 |
| #10 | 0.1900 | 0.361 | 0.347 | 0.101 | 0.091 | 0.020 | 1/8 | 0.125 | 0.070 | 0.220 | 0.210 | 1.00 |
| 1/4" | 0.2500 | 0.437 | 0.419 | 0.132 | 0.122 | 0.031 | 5/32 | 0.156 | 0.087 | 0.290 | 0.280 | 1.00 |
| 5/16" | 0.3125 | 0.547 | 0.527 | 0.166 | 0.152 | 0.031 | 3/16 | 0.188 | 0.105 | 0.353 | 0.343 | 1.00 |
| 3/8" | 0.3750 | 0.656 | 0.636 | 0.199 | 0.185 | 0.031 | 7/32 | 0.219 | 0.122 | 0.415 | 0.405 | 1.25 |
| 7/16" | 0.4375 | 0.765 | 0.746 | 0.231 | 0.218 | 0.031 | 1/4 | 0.250 | 0.140 | 0.478 | 0.468 | 1.50 |
| 1/2" | 0.5000 | 0.875 | 0.851 | 0.265 | 0.245 | 0.046 | 5/16 | 0.312 | 0.175 | 0.560 | 0.540 | 2.00 |
| 5/8" | 0.6250 | 1.000 | 0.970 | 0.331 | 0.311 | 0.062 | 3/8 | 0.375 | 0.210 | 0.685 | 0.665 | 2.00 |
| 3/4" | 0.7500 | 1.125 | 1.105 | 0.375 | 0.355 | 0.062 | 7/16 | 0.437 | 0.245 | 0.740 | 0.720 | 2.50 |
All dimensions in inches, per ASME B18.3-2012. Button heads are not recommended above the maximum standard lengths shown. Confirm requirements with our estimating team.
Standards.
What are button head cap screws?
Button heads put a broad, low dome over a hex socket — more bearing area than a low head cap, a cleaner look than a standard SHCS, and no sharp edges to catch. They finish guards, panels and covers all over machine building.
- Low-profile domed head
- Broad bearing surface — good on thin or soft material
- Not for maximum-preload joints
- #0 through 3/4″
Other names
- Button socket screws
- BHCS
- Dome head screws
- Round socket screws
Tips for purchasing
- Mind the max standard length column — long button heads are not standard.
- Shallow sockets strip before the thread does — use quality keys and honest torque.
- For structural preload, step up to a socket head cap screw.
- Certs and traceability on request.
Materials.
Representative capabilities — every item is manufactured or certified to your specification. Confirm requirements with our estimating team.
