HOLE PATTERNS
Bolt Circle Setup and Verification
Convert each equally spaced angle to X/Y coordinates and prove the reference feature.
SHORT ANSWER
The decision in one minute
For a radius R and angle θ, X = center X + R cos θ and Y = center Y + R sin θ. Use the drawing datum and confirm direction and starting angle before machining.
Document the coordinate convention
Record the datum, zero, direction, and starting angle. A correct equation with an ambiguous convention still makes the wrong pattern.
Verify the first feature
Check center, radius, offset, and first-hole coordinate before continuing; inspect to the drawing datums and tolerance.
A practical workflow
- Confirm the drawing datum.
- Set center and starting angle.
- Review coordinates.
- Verify first feature.