Countersunk Hole Size Chart for Socket Flat Head Screws (ANSI Inch)
ANSI Inch countersunk hole size chart for socket flat head screws, including pilot hole diameters for close, normal, and loose fits, countersink diameters, and angles
Socket Flat Head Screw Countersunk Hole Chart (ANSI Inch)
| Fastener Size (Thread) | Pilot Hole Diameter (inches) | Countersink Diameter (inches) | Countersink Angle (°) | ||
|---|---|---|---|---|---|
| Close Fit | Normal Fit | Loose Fit | |||
| #0 | 1/15 | 6/79 | 3/32 | 5/32 | 82 |
| #1 | 3/37 | 4/45 | 8/77 | 3/16 | 82 |
| #2 | 3/32 | 7/69 | 7/62 | 7/32 | 82 |
| #3 | 5/47 | 8/69 | 9/70 | 1/4 | 82 |
| #4 | 3/25 | 9/70 | 14/97 | 9/32 | 82 |
| #5 | 9/64 | 5/32 | 11/64 | 5/16 | 82 |
| #6 | 2/13 | 10/59 | 5/27 | 11/32 | 82 |
| #8 | 9/50 | 10/51 | 13/61 | 3/8 | 82 |
| #10 | 15/73 | 21/95 | 5/21 | 7/16 | 82 |
| 1/4 | 17/64 | 9/32 | 19/64 | 9/16 | 82 |
| 5/16 | 21/64 | 11/32 | 23/64 | 11/16 | 82 |
| 3/8 | 25/64 | 13/32 | 27/64 | 27/32 | 82 |
| 7/16 | 29/64 | 15/32 | 31/64 | 29/32 | 82 |
| 1/2 | 17/32 | 9/16 | 39/64 | 1 | 82 |
| 5/8 | 21/32 | 11/16 | 47/64 | 1 1/4 | 82 |
| 3/4 | 25/32 | 13/16 | 29/32 | 1 1/2 | 82 |
| 7/8 | 29/32 | 15/16 | 1 1/32 | 1 3/4 | 82 |
| 1 | 1 1/32 | 1 3/32 | 1 5/32 | 2 | 82 |
| 1 1/8 | 1 5/32 | 1 7/32 | 1 5/16 | 2 1/4 | 82 |
| 1 1/4 | 1 9/32 | 1 31/90 | 1 7/16 | 2 1/2 | 82 |
| 1 3/8 | 1 7/16 | 1 1/2 | 1 39/64 | 2 3/4 | 82 |
| 1 1/2 | 1 9/16 | 1 5/8 | 1 47/64 | 3 | 82 |
About ANSI Inch Countersunk Hole Sizes for Socket Flat Head Screws
This ANSI Inch countersunk hole size chart for socket flat head screws provides standardized dimensions in inches according to the ANSI Inch standard. It lists recommended pilot hole diameters for close fit (H12), normal fit (H13), and loose fit (H14), along with the corresponding countersink diameters and standard countersink angles.
Using accurate ANSI Inch countersunk hole dimensions ensures proper screw seating, flush head alignment, and reliable mechanical performance in inch-based fastening applications. This reference is essential for engineers, machinists, and designers working with ANSI Inch socket flat head screws, including:
- Mechanical and product design projects requiring ANSI Inch socket flat head screws in inch-based systems.
- Machining, drilling, and fabrication processes that need precise pilot hole and countersink preparation for standard socket flat head screws.
- Assembly and quality control operations ensuring proper fit, alignment, and flush seating of socket flat head screw heads.
Key Terms in the ANSI Inch Socket Flat Head Screw Countersunk Hole Chart
- Pilot Hole Diameter (H12 / H13 / H14): The drilled hole diameter defining screw clearance, categorized by tolerance grade for close, normal, or loose fit.
- Countersink Diameter: The circular conical recess machined to allow the ANSI Inch socket flat head screw to sit flush with the surface.
- Countersink Angle: The included angle of the conical recess, typically 82° for standard ANSI Inch flat head screws.
- ANSI Inch Standard: The American National Standards Institute (ANSI) Inch specification defining dimensions, tolerances, and geometry for inch-series socket flat head screws.
Referencing this ANSI Inch socket flat head screw countersunk chart ensures consistent part design, precise manufacturing, and compliance with international inch-based fastener standards. Proper use of these dimensions improves assembly quality, reduces machining errors, and enhances the reliability of mechanical systems.