Cutter Location - Cutter Location Against Triangles

Cutter Location Against Triangles

Start with the XY component for a cutter location and loop across every triangle in the model. For each triangle which crosses under the circular shadow of the cutter, calculate the Z value of the cutter location required for it to exactly touch the triangle, and find the maximum of all such values. Hwang et al. describe this approach in 1998, for cylindrical, ball-end, and bull-end milling tools. These ideas are further developed in a 2002 paper by Chuang et al. In a paper from 2004 Yau et al. describe an algorithm for locating an APT-cutter against triangles. Yau et al. use a kd-tree for finding overlapping triangles.

Problems: requires a lot of memory to hold enough triangles to register the model at a tight enough tolerance, and it takes longer to program to get your initial cutter location values. However, they are at least guaranteed valid in all cases.

This is how all major CAM systems do it these days because it works without failing no matter what the complexity and geometry of the model, and can be made fast later. Reliability is far more important than efficiency.

The above refers to 3-axis machines. 5-axis machines need a special entry of their own.