Counterbore Hole Size Chart for Pan Head Screws (ANSI Metric)
ANSI metric counterbore hole size chart for pan head screws, including pilot hole diameters for close, normal, and loose fits, counterbore diameters, and depths (millimeters)
Pan Head Screw Counterbore Hole Chart (ANSI Metric)
| Fastener Size | Pilot Hole Diameter (mm) | Counterbore Diameter (mm) | Counterbore Depth (mm) | ||
|---|---|---|---|---|---|
| Close Fit (H12) | Normal Fit (H13) | Loose Fit (H14) | |||
| M2 | 2.2 | 2.4 | 2.6 | 7 | 2.1 |
| M2.5 | 2.7 | 2.9 | 3.1 | 8 | 2.6 |
| M3 | 3.2 | 3.4 | 3.6 | 10 | 2.9 |
| M3.5 | 3.7 | 3.9 | 4.2 | 11 | 3.2 |
| M4 | 4.3 | 4.5 | 4.8 | 13 | 3.6 |
| M5 | 5.3 | 5.5 | 5.8 | 15 | 4.5 |
| M6 | 6.4 | 6.6 | 7 | 18 | 5.5 |
| M8 | 8.4 | 9 | 10 | 24 | 6.8 |
| M10 | 10.5 | 11 | 12 | 28 | 8.5 |
About ANSI Metric Counterbore Hole Sizes for Pan Head Screws
This ANSI metric counterbore hole size chart for pan head screws provides engineers, designers, and machinists with standardized dimensions based on American National Standards Institute (ANSI) metric specifications. It includes the recommended pilot hole diameters for close fit (H12), normal fit (H13), and loose fit (H14) tolerances, along with the appropriate counterbore diameters and counterbore depths in millimeters.
Using accurate ANSI metric counterbore dimensions ensures proper screw head clearance, uniform seating, and dependable fastening performance in metric-based mechanical assemblies. This chart supports precision design and manufacturing across various engineering applications, including:
- Mechanical and product design involving pan head machine screws conforming to ANSI metric standards.
- Machining, drilling, and fabrication processes that require precise pilot hole and counterbore preparation for metric fasteners.
- Assembly and quality control operations ensuring proper fit, alignment, and flush seating of screw heads in mechanical components.
Key Terms in the ANSI Metric Counterbore Hole Chart
- Pilot Hole Diameter (H12 / H13 / H14): The drilled hole diameter that defines clearance or fit for the screw shank, categorized by tolerance grade.
- Counterbore Diameter: The circular recess machined to allow the pan head screw to sit flush or slightly below the surface.
- Counterbore Depth: The vertical depth corresponding to the screw head height, ensuring proper engagement without interference.
- ANSI Metric Standard: The American National Standards Institute specification that governs the dimensions and tolerances for metric-series fasteners, including pan head screws.
Referencing this ANSI metric pan head screw counterbore hole size chart ensures consistency, dimensional precision, and compliance with metric engineering standards. Accurate application of these values improves assembly quality, reduces machining errors, and enhances the overall reliability of mechanical systems.