How this calculator works
The full turn is divided by the number of holes. Polar coordinates give each centre relative to the selected origin. Check your machine coordinate convention and work offset before transferring the table.
Formula
theta_i = theta_0 +/- 2 pi i / N; X_i = Xc + R cos(theta_i); Y_i = Yc + R sin(theta_i); chord = 2R sin(pi/N).
Worked example
Four holes on a 100 mm diameter circle starting at zero have centres (50,0), (0,50), (-50,0) and (0,-50) mm.
Advertisement
Frequently asked questions
Is radius the same as bolt circle diameter?
Radius is half the bolt circle diameter. Enter 50 mm for a 100 mm bolt circle.
Does the table include hole diameter?
No. Coordinates locate hole centres. Hole size, edge distance and fit need separate specification.
Can I offset the pattern?
Yes. Add the centre X and Y coordinates in the same coordinate system as your drawing.