1. What is Bolt Circle Diameter?

The Bolt Circle Diameter (BCD) is the diameter of the circle that passes through the center of all the bolt holes in a circular pattern. It's a crucial measurement in mechanical design and engineering for components like gears, flanges, and chainrings.

2. How Does the Calculator Work?

The calculator uses the BCD formula:

Where:

• \( r \) — Radius of the bolt circle (inches)
• \( n \) — Number of bolts (dimensionless)
• \( \sin \) — Trigonometric sine function

Explanation: The formula calculates the chord length between adjacent bolts and uses this to determine the diameter of the bolt circle.

3. Importance of BCD Calculation

Details: Accurate BCD measurement is essential for proper component alignment, load distribution, and ensuring interchangeability of parts in mechanical assemblies.

4. Using the Calculator

Tips: Enter the radius from center to bolt hole in inches and the number of bolts (minimum 3). The calculator will compute the Bolt Circle Diameter.

5. Frequently Asked Questions (FAQ)

Q1: What's the minimum number of bolts needed?
A: The minimum is 3 bolts to form a circle. The formula works for any number of bolts ≥3.

Q2: Can I use this for metric measurements?
A: Yes, just enter the radius in millimeters instead of inches. The result will be in millimeters.

Q3: How accurate is this calculation?
A: The calculation is mathematically precise. Any inaccuracy comes from measurement errors in the radius.

Q4: What if my bolt pattern isn't circular?
A: This calculator only works for circular patterns. Other patterns require different calculations.

Q5: Can I calculate radius from BCD?
A: Yes, the formula can be rearranged: \( r = BCD / (2 \times \sin(180° / n)) \).