For the FELIX Tec 4 and Pro series. The extruder heaters heatup before a z-home movement (negative z-movement untill endswitch is triggered) is performed.

This is done for the following reasons.

• Prevent damage of kapton in case there is a small plastic blob on the nozzle especially for the TEC
• Also for the pro series it gives more reliable probing results.

The latest firmwares shows more information on the screen when a z-homing or calibration routine is started, but for older versions the interface would worst case freeze for 2 minutes until the desired probing temperature is reached.