Rather than having the coordinate words vary with which plane is selected (G17, G18, or G19), Mach3 just uses the “A” and “B” words. R specifies the angle of rotation in degrees, counterclockwise.įor Mach3, we use a slightly different syntax: In the example, we had the circle center at X0Y0. Where, alpha and beta are words for the 2 coordinates of the circle’s center we want to rotate about. Syntax for G68 Coordinate System Rotation (Fanuc & Mach3) This is one of the many tricks discussed in our CAM Toolpath Considerations page of the Feeds and Speeds Cookbook. You’ll get a much better finish if your tool arcs into the cut rather than just heading straight in along a line. G68 rotated the “arched doorway” slot through 3 calls of a subprogram to create 3 slots…īTW, those fans in the middle of each pocket are tool entry and exit paths. G0 Z3 G0 X0 Y0 M99Īnd here is what the simulation in G-Wizard Editor looks like: M98 P0071 G69 (Turn off coordinate rotation so it doesn’t confuse us later! ) G0 G90 Z250 M9 G0 G91 G28 Z0 Y0 M5 M30 M98 P0071 ( Third time we rotate 240 degrees M98 P0071 ( Second time we rotate 120 degrees ) ( Example use of G68 to make 3 slots in a circle ) T10 M6 G0 G90 G54.1 P20 X0 Y0 S8000 M3 G43 Z3 H22 D22 M8 ( First time we don’t rotate the slot ) We write a subprogram to do the arched doorway, and we want to be able to rotate the coordinates as we call the doorway subprogram for each slot. Let’s suppose we have a part that requires 3 “arched doorway” slots. This is a perfect excuse to use G68 coordinate system rotation. The repeats are all laid out on a circle around some center point. Consider, for example, a case where you want to repeat a pocket or slot multiple times on a part. It can be very convenient to be able to execute g-code with the assumption that the coordinate system has been rotated. G68 & G69 G Codes: CNC Coordinate Rotation Introduction

Cnc mach3 program