1. What is Clearance Hole Diameter?

The clearance hole diameter (CH) is the recommended hole size for a fastener to pass through while allowing proper alignment and movement. It's calculated as the average of the fastener diameter (D) and head diameter (DH).

2. How Does the Calculator Work?

The calculator uses the clearance hole equation:

Where:

• \( CH \) — Clearance hole diameter (inches)
• \( D \) — Fastener diameter (inches)
• \( DH \) — Fastener head diameter (inches)

Explanation: The equation provides an optimal hole size that accommodates both the fastener shaft and its head.

3. Importance of Clearance Hole Calculation

Details: Proper clearance holes ensure correct fastener installation, prevent binding, and allow for thermal expansion or misalignment while maintaining structural integrity.

4. Using the Calculator

Tips: Enter both fastener diameter and head diameter in inches. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why use this formula for clearance holes?
A: This formula provides a balanced hole size that accommodates both the fastener shaft and head while maintaining proper alignment.

Q2: What are typical clearance hole tolerances?
A: Standard clearance holes typically have +0.002" to +0.005" tolerance over nominal size, depending on application.

Q3: When should I use a different clearance formula?
A: For precision applications or special fastener types (like shoulder bolts), consult specific engineering standards.

Q4: Does material affect clearance hole size?
A: Yes, softer materials may require slightly larger clearances to account for compression or deformation.

Q5: What about metric measurements?
A: The same formula applies - just use consistent metric units (millimeters) for all measurements.