The most recognizable coordinates can be found on the vertical milling machine. Imagine that you are standing in front of the machine and facing it. The coordinates of this machine follow the right-hand rule shown in Figure 1. As you can see in Figure 2, the X-axis describes left and right motion of the cutting tool, the Y-axis describes back and forth motion of the tool, and the Z-axis describes up and down motion.
Depending on the machine, either the cutting tool or the worktable will move during machining operations. The positive and negative directions on each axis always describe the motion of the cutting tool in relation to the worktable. If the cutting tool is the movable part, the positive directions follow the right-hand rule. However, if the worktable moves, the positive and negative directions are reversed. As shown in Figure 3, table movement to the left is actually a positive motion because it shifts the position of the cutting tool to the right of the table.
Depending on the machine, either the cutting tool or the worktable will move during machining operations. The positive and negative directions on each axis always describe the motion of the cutting tool in relation to the worktable. If the cutting tool is the movable part, the positive directions follow the right-hand rule. However, if the worktable moves, the positive and negative directions are reversed. As shown in Figure 3, table movement to the left is actually a positive motion because it shifts the position of the cutting tool to the right of the table.
 |
| The right-hand rule matches a vertical machining center |
 |
Directions of positive and negative spindle movement on a basic mill. |
 |
. As a tool moves from rest (A) to the right (B), it travels in a positive direction along the X-axis. Table movement to the left (C) also moves the tool in a positive direction along the X-axis. |
