How do I choose the right fit type for my clearance hole?

Choose fit type based on your application: Close Fit (0.05× bolt diameter) for precision assemblies, Normal Fit (0.1× bolt diameter) for general purpose, Free Fit (0.15× bolt diameter) for quick assembly, and Loose Fit (0.2× bolt diameter) for field assembly. Consider factors like vibration, thermal expansion, and assembly frequency.

What factors affect clearance hole sizing?

Bolt diameter, fit type, material properties, manufacturing tolerance, thermal expansion, vibration, and assembly requirements all affect hole sizing. Different materials have different expansion coefficients, and the application environment (temperature, humidity, vibration) can impact the required clearance.

How do I handle material expansion in clearance hole calculations?

Consider thermal expansion coefficients when calculating clearance holes. Aluminum expands more than steel, so it requires larger clearances. For temperature variations, add extra clearance based on the material's expansion coefficient and expected temperature range. Use the material with the highest expansion coefficient when joining different materials.

What are the standard tolerances for clearance holes?

Standard tolerances vary by precision level: Precision (±0.05mm) for high-accuracy applications, Standard (±0.1mm) for general manufacturing, and Rough (±0.2mm) for basic applications. Choose tolerance based on your manufacturing capabilities and application requirements. Tighter tolerances require more precise drilling equipment.

How do I ensure proper thread engagement with clearance holes?

Ensure minimum thread engagement of 1.5× bolt diameter in the threaded material. The clearance hole should only be in the non-threaded material. For through holes, the clearance should be large enough to prevent thread interference while maintaining proper alignment. Consider using washers to distribute load and prevent material damage.

Clearance Hole Calculator

Hole Details

Bolt Diameter

Diameter of the bolt

Fit Type

Type of fit required

Material Type

Type of material

Tolerance

Manufacturing tolerance

Calculation Results

Clearance Hole Calculator: Your Guide to Hole Sizing

Need to calculate the correct clearance hole size for your bolts? Our Clearance Hole Calculator helps you determine the optimal hole diameter based on bolt size, fit type, and material.

Understanding Clearance Hole Calculations

Clearance hole calculations are important for several reasons:

Assembly Fit: Proper bolt clearance
Material Strength: Optimal hole size
Manufacturing: Accurate drilling
Quality Control: Consistent results
Project Planning: Better scheduling

How to Use the Clearance Hole Calculator

Enter Bolt Size: Input bolt diameter
Select Fit: Choose fit type
Set Material: Choose material type
Add Tolerance: Specify tolerance
Click Calculate: Get detailed results

Clearance Hole Calculation Formulas

Hole Diameter:
D = B + C + T

Clearance:
C = B × F

Where:
D = Hole diameter
B = Bolt diameter
C = Clearance
T = Tolerance
F = Fit factor

Common Clearance Hole Specifications

Fit Types:
- Close Fit: 0.05 × bolt diameter
- Normal Fit: 0.1 × bolt diameter
- Free Fit: 0.15 × bolt diameter
- Loose Fit: 0.2 × bolt diameter
Material Types:
- Steel: Standard clearance
- Aluminum: 1.2 × standard
- Plastic: 1.5 × standard
- Wood: 2 × standard
Common Applications:
- Precision Assembly: Close fit
- General Purpose: Normal fit
- Quick Assembly: Free fit
- Field Assembly: Loose fit
Standard Tolerances:
- Precision: ±0.05mm
- Standard: ±0.1mm
- Rough: ±0.2mm

Real-World Examples

Example 1: Standard Bolt Hole

Bolt Diameter: 10mm
Fit Type: Normal Fit
Material Type: Steel
Tolerance: 0.1mm
Results:
- Clearance: 1mm
- Hole Diameter: 11.1mm
- Recommended Drill: 11mm

Example 2: Aluminum Assembly

Bolt Diameter: 8mm
Fit Type: Free Fit
Material Type: Aluminum
Tolerance: 0.1mm
Results:
- Clearance: 1.44mm
- Hole Diameter: 9.54mm
- Recommended Drill: 9.5mm

Frequently Asked Questions

How to choose fit type?

Depends on application requirements and assembly needs.

What about material expansion?

Consider thermal expansion for temperature variations.

How to handle multiple materials?

Use the material with highest expansion coefficient.

What about thread engagement?

Ensure minimum thread engagement of 1.5 × bolt diameter.

How to calculate edge distance?

Minimum edge distance should be 1.5 × hole diameter.