Get the X/Y coordinates and a visual diagram for every hole in a bolt circle or flange pattern, evenly spaced around the center.
How This Is Calculated
Each hole sits at an angle stepped evenly around the circle (360 degrees divided by the hole count), starting from whatever angle you set. From there, basic trigonometry (cosine for X, sine for Y) turns that angle and the circle's radius into a flat coordinate for each hole.
Worked Example
A 6 inch bolt circle with 8 holes starting at 0 degrees places holes every 45 degrees, with the first hole at (3, 0) and the second at roughly (2.12, 2.12).
Common Mistakes
- Entering diameter when the field asks for radius, or vice versa, which doubles or halves every coordinate.
- Assuming a 0 degree start angle matches your part's actual reference feature; rotate the start angle to match your drawing's datum.
- Not verifying hole count against the actual flange or pattern spec before cutting; an extra or missing hole silently shifts every subsequent angle.
Frequently Asked Questions
- What is PCD?
- Pitch Circle Diameter, the diameter of the imaginary circle passing through the center of every hole in the pattern.
- How do I match this layout to my part's actual orientation?
- Adjust the start angle input to match wherever your first hole should sit relative to your part's reference datum or keyway.
- Can this handle uneven hole spacing?
- No, it assumes holes are spaced evenly around the full circle. Uneven patterns need to be laid out manually or with CAD.