What are the possible causes of a CNC machine displaying a 'soft overtravel limit' error, and how do you resolve it?

A 'soft overtravel limit' error on a CNC machine indicates that a commanded axis movement has exceeded a programmed software limit. These software limits, stored in the machine's parameters, define the permissible travel range for each axis. Several factors can trigger this error. First, programming errors can cause it. An incorrect coordinate in the CNC program can command the axis to move beyond its limit. Second, incorrect work offsets can cause it. An improperly set work offset can shift the coordinate system, causing the programmed movements to exceed the soft limits. Third, machine setup errors can cause it. If the workpiece or fixture is positioned incorrectly on the machine table, the programmed movements may exceed the soft limits. Fourth, parameter settings can cause it. The soft overtravel limits themselves may be set incorrectly, restricting the axis movement unnecessarily. Fifth, encoder issues can cause it. A faulty encoder can provide incorrect position feedback, leading the control system to believe the axis has exceeded its limit. To resolve a soft overtravel limit error, first identify the affected axis and the direction of the overtravel. This information is typically displayed in the error message. Then, review the CNC program. Check the program for any incorrect coordinates or commands that might be causing the overtravel. Verify the work offset settings. Ensure the work offsets are correctly set and that they are not shifting the coordinate system beyond the soft limits. Check the machine setup. Ensure the workpiece and fixture are properly positioned on the machine table. Review the soft overtravel limit parameters. Verify the soft overtravel limit parameters are set correctly. If necessary, increase the limits, but only after carefully considering the potential for collisions. Inspect the encoder. Check the encoder signals for noise or distortion. If the encoder is faulty, it may need to be replaced. Finally, manually jog the axis away from the limit. After identifying and correcting the cause of the error, manually jog the axis away from the limit using the machine's jog mode. After correcting the error, run a test program to verify that the overtravel limit is no longer triggered.