When working with the print bed, which is set at Z=0 by convention, it is fine to work in machine coordinates. However, when working with any other workholding method, it is important to utilize a Workpiece Coordinate System (WCS). This defines a local coordinate system for printing or milling, while still respecting the machine axis limits. Do not change the zero position of the machine because it may lead to crashes.
WCS coordinates (G54-G59.3) are stored at the bottom of the Offsets page:
In order to change a WCS value, click on the value you wish to change, and you may type in the new value:
In order to find exact edges and surfaces of objects, you may use the probe:
- Select "Probe" from the Tool Table
- Jog the machine until it is off the edge to be probed
- Click the relevant button for the direction you want to probe (the movement is limited to 30mm):
- Type the machine coordinates into the relevant Workplace Coordinate value (remember to add or subtract the radius of the probe depending on your travel direction. The default probe tip has a radius of 1mm)