Abstract
This report describes how to create an offset surface between any tool shapes and machining surface to a necessary level of accuracy in 3 axis machine tool. It is able to consider that the machining surface is constituted by many elements, which are cutting points. An offset surface between the tool shape and an element is able to define as a reversed tool shape with Z-direction. Accordingly, the offset surface of the machining surface may be regarded as an envelope which is obtained by set operation of offset surfaces for those elements. In order to execute these set operations by computer, a spatial array is employed as a memorizing area of the offset surface. And also in order to save memory capacity, a quad-tree data structure is employed.
