In the section "Setting the Machining Coordinate System" of CNC process fundamentals, 

the method of setting the machining coordinate system using tool setting has been introduced. 

This method is also applicable to machining centers. Since machining centers use multiple tools and 

can perform automatic tool changes, it is necessary to measure the basic dimensions of each tool used and 

store these measurements in the CNC system for use during machining. This process, known as tool setting for machining centers,

 typically uses an external tool presetter.


The basic structure of a tool presetter is shown in Figure 5.29. In Figure 5.29, a tool holder shaft (2) is mounted on the platform (7)

 of the tool presetter, used for installing the tool to be measured, such as the drilling tool shown in Figure 5.30. By using the rapid 

movement button (4) and the fine adjustment knobs (5) or (6), the position of the tool holder shaft (2) on the platform (7) can be

 adjusted. When the light source emitter (8) is turned on, the tool edge is projected and magnified onto the display screen (1), 

allowing measurement of the tool's dimensions in the X (radial dimension) and Z (length from the tool holder reference surface to

 the tool tip) directions.


The tool setting process for a drilling tool is as follows:

1. Connect and install the tool to be measured with the tool holder as a single unit.

2. Insert the tool holder into the tool holder shaft (2) on the tool presetter and secure it.

3. Turn on the light source emitter (8) and observe the projection of the tool edge on the display screen (1).

4. Use the rapid movement button (4) and the fine adjustment knobs (5) or (6) to adjust the position of the tool edge projection on 

the display screen (1), aligning the tool tip with the center of the crosshair on the display screen, as shown in Figure 5.31.

5. Measure X as 20, indicating the tool diameter is φ20mm, which can be used for tool radius compensation.

6. Measure Z as 180.002, indicating the tool length is 180.002 mm, which can be used for tool length compensation.

7. Input the measured dimensions into the tool compensation page of the machining center.

8. Remove the measured tool from the tool presetter, and it is now ready for use in the machining center.