TOOL TOUCHOFF

This section describes how QtDragon is used to set the tool tip to Z0 in user workspace. For machines that use premeasured tools and have Tool Length Offsets (TLO) programmed into the LinuxCNC tool table, these functions can be used to measure the tool lengths relative to a reference tool or relative to a gage line, but the topic of TLOs and G43 compensation is beyond the scope of this document.

GO TO SENSOR

When pressed, the spindle will move to Z0 in absolute coordinates and then make a direct move to the X and Y coordinates specifed in the SETTINGS page for TOOL SENSOR LOCATION. The same result could be achieved by setting TOOL_CHANGE_QUILL_UP = 1 and TOOL_CHANGE_AT_G30 = 1 in the INI file. This button is simply a convenience function.

TOOL TOUCHOFF Z

Typical touchplate for CNC

Touchplate - When the Touchplate checkbox on the SETTINGS -> Tool Touchoff section is checked, this button is used to set the Z0 position of the tool tip by probing down toward the workpiece until the Probe signal is triggered. At this point, the Z axis offset is set to the thickness of the touchplate. If the touchplate was placed on the top surface of the workpiece, then Z0 is the top of the workpiece.

In this setup, the touchplate is connected to ground and an alligator clip, which is connected to the Probe input of the controller, is connected to the tool. When the tool contacts the touchplate, the Probe signal is triggered and the Z offset is programmed into the machine controller.

Manual tool setter gauge

Manual Touchoff - Once the tool is at the X and Y coordinates corresponding to the tool sensor location specified in the SETTINGS page, jog Z down until the gauge reads 0.000. (It is assumed the gauge has been calibrated to read 0 as a reference point.) Then press the TOOL TOUCHOFF Z button. The value on the SETTINGS page for TOOL SENSOR HEIGHT minus the WORKPIECE HEIGHT specified on the MAIN page is now the Z offset for that tool. This makes Z0 on the top of the workpiece, assuming that the tool sensor was placed on the machine bed and not the workpiece. If the workpiece is held in a vice or some other fixture, the workpiece height is the distance from the machine bed to the top of the workpiece.

Automatic tool setter

Automatic Touchoff - Once the tool is at the X and Y coordinates corresponding to the tool sensor location specified in the SETTINGS page, pressing the TOOL TOUCHOFF Z button will start a Z probing routine with parameters as specified in SETTINGS - Touchoff. The Z0 is then set in the same way as Manual operation. The only real difference between Auto and Manual mode is that in Auto, the controller probe input signal is used to set the Z0 offset and in Manual, pressing the button sets the Z0 offset.

Use extreme caution when using AUTO mode touchoff procedures. Ensure that the Probe input signal is functional. Failing to trigger a Probe signal while executing a probing routine can result in a broken tool, a ruined workpiece or damage to the machine.