Counterbore Hole Size Chart for Socket Head Screws (ANSI Inch)
ANSI inch counterbore hole size chart for socket head screws, including pilot hole diameters for close, normal, and loose fits, counterbore diameters, and depths (inches)
Socket Head Screw Counterbore Hole Chart (ANSI Inch)
| Fastener Size | Pilot Hole Diameter (in) | Counterbore Diameter (in) | Counterbore Depth (in) | ||
|---|---|---|---|---|---|
| Close Fit | Normal Fit | Loose Fit | |||
| #0 | 1/15 | 6/79 | 3/32 | 1/8 | 6/79 |
| #1 | 3/37 | 4/45 | 8/77 | 5/32 | 2/23 |
| #2 | 3/32 | 7/69 | 7/62 | 3/16 | 5/49 |
| #3 | 5/47 | 8/69 | 9/70 | 7/32 | 10/87 |
| #4 | 3/25 | 9/70 | 14/97 | 7/32 | 11/86 |
| #5 | 9/64 | 5/32 | 11/64 | 1/4 | 11/78 |
| #6 | 2/13 | 10/59 | 5/27 | 9/32 | 2/13 |
| #8 | 9/50 | 10/51 | 13/61 | 5/16 | 9/50 |
| #10 | 15/73 | 21/95 | 5/21 | 3/8 | 8/39 |
| 1/4 | 17/64 | 9/32 | 19/64 | 7/16 | 25/89 |
| 5/16 | 21/64 | 11/32 | 23/64 | 17/32 | 12/35 |
| 3/8 | 25/64 | 13/32 | 27/64 | 5/8 | 28/69 |
| 7/16 | 29/64 | 15/32 | 31/64 | 23/32 | 38/81 |
| 1/2 | 17/32 | 9/16 | 39/64 | 13/16 | 43/81 |
| 5/8 | 21/32 | 11/16 | 47/64 | 1 | 61/93 |
| 3/4 | 25/32 | 13/16 | 29/32 | 1 3/16 | 57/73 |
| 7/8 | 29/32 | 15/16 | 1 1/32 | 1 3/8 | 77/85 |
| 1 | 1 1/32 | 1 3/32 | 1 5/32 | 1 5/8 | 1 1/16 |
| 1 1/4 | 1 9/32 | 1 31/90 | 1 7/16 | 2 | 1 5/16 |
| 1 1/2 | 1 9/16 | 1 5/8 | 1 47/64 | 2 3/8 | 1 9/16 |
| 1 3/4 | 1 13/16 | 1 7/8 | 2 | 2 3/4 | 1 13/16 |
| 2 | 2 1/16 | 2 1/8 | 2 1/4 | 3 1/8 | 2 1/16 |
About ANSI Inch Counterbore Hole Sizes for Socket Head Screws
This ANSI inch counterbore hole size chart for socket head screws provides standardized dimensions in inches according to American National Standards Institute (ANSI). It lists recommended pilot hole diameters for close fit, normal fit, and loose fit, along with the corresponding counterbore diameters and counterbore depths in inches.
Using accurate ANSI inch counterbore dimensions ensures proper screw seating, head clearance, and reliable mechanical performance in inch-based fastening applications. This reference is essential for engineers, machinists, and designers working with ANSI socket head screws, including:
- Mechanical and product design projects requiring ANSI socket head screws in inch systems.
- Machining, drilling, and fabrication processes that need precise pilot hole and counterbore preparation for standard socket head screws.
- Assembly and quality control operations ensuring proper fit, alignment, and flush seating of socket head screw heads.
Key Terms in the ANSI Inch Socket Head Screw Counterbore Chart
- Pilot Hole Diameter: The drilled hole diameter defining screw clearance, categorized for close, normal, or loose fit.
- Counterbore Diameter: The circular recess machined to allow the ANSI socket head screw to sit flush or slightly below the surface.
- Counterbore Depth: The vertical depth of the recess matching the head height of the ANSI socket head screw.
- ANSI Standard: The American National Standards Institute specification defining dimensions, tolerances, and geometry for inch-series socket head screws used in mechanical assemblies.
Referencing this ANSI inch socket head screw counterbore chart ensures consistent part design, precise manufacturing, and compliance with international inch fastener standards. Proper use of these dimensions improves assembly quality, reduces machining errors, and enhances the reliability of mechanical systems.