M14 is one of the standard coarse-thread sizes for slotted countersunk head screw under GB/T 68 / ISO 2009. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M14 Dimensional Row (GB/T 68 / ISO 2009)
| Size | Pitch (mm) | Length L (mm) | Head diameter dk (mm) | Head height k (mm) | Cross recess | Countersink angle (deg) | Reference standard |
|---|---|---|---|---|---|---|---|
| M14 | 2.0 | 80 | 25.0 | 7.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
Spanner & Drive for M14 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039)
The hex socket for M14 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039) is shown in the spec table — use the matching Allen / hex key (an ISO 2936 hex key set covers the full range). A T-handle Allen key gives the best feel for setting preload by feel; for production work use a torque-controlled driver.
Hole Sizes for M14
| Coarse-thread pitch (ISO 724) | 2 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 15.5 mm |
| Tapping drill, coarse thread | 12 mm |
Tightening Torque for M14
| Class 8.8 (dry, ~µ 0.125) | ≈ 135 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 190 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 230 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M14
| Tensile stress area As (ISO 898-1) | 115 mm² |
|---|---|
| Proof load, class 8.8 | 67 kN |
| Proof load, class 10.9 | 95 kN |
| Proof load, class 12.9 | 112 kN |
| Min. ultimate tensile, class 8.8 | 92 kN |
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
M14 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039) Weight
A steel M14 slotted countersunk head screw at the listed 80 mm length weighs approximately 308 g each — about 308 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³). Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only.
Common Applications for M14 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039)
M14 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039) are commonly specified for heavier machine assembly and equipment mounting.
Installation Tips for M14 Slotted Countersunk Head Screw — GB/T 68 / ISO 2009 (Series 039)
- Use a quality Allen key fully seated in the socket — partial engagement is the most common cause of stripped sockets at this size.
- For countersunk and button-head variants, chamfer the through-hole to seat the head flush without preloading the head/shank fillet.
Mating Parts for M14
For M14, pair with a M14 hex nut (ISO 4032 / DIN 934) and, where used, a M14 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.