Formula to mill radius

[racewayron]

Is there a formula to set the head tilt in order to machine a radius in bar stock? Years ago I saw a shop that was cutting a radius in bar stock by tilting the milling machine head and using a large end mill. I need to do this in aluminum. Thank you. Ron

[vegipete]

Although I make no claims for accuracy, cutter radius divided by the sine of the angle away from vertical appears to give an approximate answer. Note though that the cut surface will actually be a section of an ellipse, not a circle. With the head over at 90 degrees, sin(90) = 1 and obviously the resulting cut radius is the same as the cutter and with the head vertical, sin(0) = 0 and the cut radius is infinity - in other words, a straight line.

[racewayron]

Thank you. I will give that a try. Ron