Counterbore Hole Size Chart for Cheese Head Fasteners (GB)
GB counterbore hole size chart for cheese head fasteners
Cheese Head Fastener Chart (GB)
| Fastener Size | Pilot Hole Diameter (mm) | Counterbore Diameter (mm) | Counterbore Depth (mm) | ||
|---|---|---|---|---|---|
| Close Fit H12 | Normal Fit H13 | Loose Fit H14 | |||
| M1.6 | 1.7 | 1.8 | 2 | 3.5 | 1.5 |
| M2 | 2.2 | 2.4 | 2.6 | 4.4 | 1.8 |
| M2.5 | 2.7 | 2.9 | 3.1 | 5.5 | 2.2 |
| M3 | 3.2 | 3.4 | 3.6 | 6.5 | 2.4 |
| M3.5 | 3.7 | 3.9 | 4.2 | 7 | 3 |
| M4 | 4.3 | 4.5 | 4.8 | 8 | 3 |
| M5 | 5.3 | 5.5 | 5.8 | 10 | 3.7 |
| M6 | 6.4 | 6.6 | 7 | 11 | 4.5 |
| M8 | 8.4 | 9 | 10 | 15 | 5.6 |
| M10 | 10.5 | 11 | 12 | 18 | 6.6 |
About GB Counterbore Hole Sizes for Cheese Head Fasteners
This GB counterbore hole size chart provides standardized dimensions for cheese head fasteners according to GB (Guobiao) standards. It includes recommended pilot hole diameters (H12, H13, H14), counterbore diameters, and counterbore depths in millimeters, ensuring proper screw seating and precise assembly in mechanical systems.
Using accurate GB counterbore hole dimensions ensures correct fastener alignment, consistent manufacturing quality, and compliance with national engineering standards. This reference is useful for engineers, machinists, and designers working with GB-standard fasteners, including:
- Mechanical engineers and product designers creating assemblies with GB-standard cheese head fasteners.
- Machinists and technicians drilling pilot holes and counterbores to achieve precise tolerances.
- Fabricators and manufacturers producing components that meet Chinese National Standard (GB) specifications.
- Assembly and maintenance professionals seeking standardized GB counterbore dimensions for reliable fastening.
Key Terms in the GB Counterbore Chart
- Pilot Hole Diameter (H12, H13, H14): Initial drilled hole guiding the screw, with different tolerance grades for fit precision.
- Counterbore Diameter: Enlarged recessed portion allowing the cheese head screw to sit flush or below the surface.
- Counterbore Depth: Depth of the recess matching the screw head height for proper seating.
- GB Standard: The Guobiao (National Standard of the People’s Republic of China) defining dimensions, tolerances, and mechanical fit requirements for fasteners.
Referencing this GB cheese head fastener counterbore hole size chart ensures accurate fastener installation, uniform tolerances, and compliance with Chinese national engineering standards. Using these dimensions improves manufacturing quality, reduces errors, and supports high-precision mechanical assembly.