Wrench size, head height and point sizes for inch square head set screws, #10 to 1-1/2″. ASME B18.6.2.
A square head set screw is turned with a wrench on its square head instead of a hex key. F is the size across the flats of the square — the wrench — and it equals the screw’s own size. G is across the corners, H the head height, C the cup or flat point diameter and P the dog or half-dog point diameter. The head sits on top, so the length is measured from under the head to the point. Inches throughout.
Letters match the table.
| Size | Wrench | F max | F min | G min | H max | H min | C max | C min | P max | P min |
|---|---|---|---|---|---|---|---|---|---|---|
| #10 | 3/16″ | 0.188 | 0.180 | 0.247 | 0.148 | 0.134 | – | – | 0.127 | 0.120 |
| 1/4″ | 1/4″ | 0.250 | 0.241 | 0.331 | 0.196 | 0.178 | 0.132 | 0.118 | 0.156 | 0.149 |
| 5/16″ | 5/16″ | 0.312 | 0.302 | 0.415 | 0.245 | 0.224 | 0.172 | 0.156 | 0.203 | 0.195 |
| 3/8″ | 3/8″ | 0.375 | 0.362 | 0.497 | 0.293 | 0.270 | 0.212 | 0.194 | 0.250 | 0.241 |
| 7/16″ | 7/16″ | 0.438 | 0.423 | 0.581 | 0.341 | 0.315 | 0.252 | 0.232 | 0.297 | 0.287 |
| 1/2″ | 1/2″ | 0.500 | 0.484 | 0.665 | 0.389 | 0.361 | 0.291 | 0.270 | 0.344 | 0.334 |
| 9/16″ | 9/16″ | 0.562 | 0.545 | – | 0.437 | 0.407 | 0.332 | 0.309 | 0.391 | 0.379 |
| 5/8″ | 5/8″ | 0.625 | 0.606 | 0.833 | 0.485 | 0.452 | 0.371 | 0.347 | 0.469 | 0.456 |
| 3/4″ | 3/4″ | 0.750 | 0.729 | 1.001 | 0.582 | 0.544 | 0.450 | 0.425 | 0.562 | 0.549 |
| 7/8″ | 7/8″ | 0.875 | 0.852 | 1.170 | 0.678 | 0.635 | 0.530 | 0.502 | 0.656 | 0.642 |
| 1″ | 1″ | 1.000 | 0.974 | 1.337 | 0.774 | 0.726 | 0.609 | 0.579 | 0.750 | 0.734 |
| 1-1/8″ | 1-1/8″ | 1.125 | 1.096 | 1.505 | 0.870 | 0.817 | 0.689 | 0.655 | 0.844 | 0.826 |
| 1-1/4″ | 1-1/4″ | 1.250 | 1.219 | 1.674 | 0.966 | 0.908 | 0.767 | 0.733 | 0.938 | 0.920 |
| 1-3/8″ | 1-3/8″ | 1.375 | 1.342 | 1.843 | 1.063 | 1.000 | 0.848 | 0.808 | 1.031 | 1.011 |
| 1-1/2″ | 1-1/2″ | 1.500 | 1.464 | 2.010 | 1.159 | 1.091 | 0.926 | 0.886 | 1.125 | 1.105 |
A dash means our two sources don’t agree on that number — give us a call at 405-670-1234. Which point to use is on the set screw chart; thread pitches are on the thread pitch chart.
Quick answers
- What size wrench fits a 1/2" square head set screw?
- A 1/2″ wrench — across the flats of the square equals the screw’s own size (0.500″ max).
- How do you measure a square head set screw?
- From under the head to the point. The head sits on top, so it isn’t part of the length.
- How tall is the head on a square head set screw?
- 0.293″ on a 3/8″, 0.389″ on a 1/2″ and 0.582″ on a 3/4″ (maximum).
- What is the cup point diameter of a 1/2" square head set screw?
- 0.291″ maximum, 0.270″ minimum.