i'm trying to define tolerances for a concave surface. it's radius
480mm, 20mm deep, giving an outside diameter of approx. 300mm. when it's machined on a lathe the tool only has to track the radius, of course. what geometric tolerancing is required to ensure the tool centre lies on the axis of rotation of the part? if it's wrong i'll end up with either a hole or a point in the middle.thanks.