For any 3D printer to understand where its print head is, it needs a reference point, called the home position. Before a 3D printer begins a print job, one of the very first actions it performs is to locate this home position. This is very important as the print head could be nearly anywhere in the space above the build platform.

To ensure that the print head is at a known position, you use a sensor or switch fitted at the ends of each axis. The switch is triggered when the print head has reached home position.


For Delta printers, the home position is at the very top of the machine. Thus the switches or sensors are usually fitted to the top frames on each of the three vertical arms in this design: When the carriages move up, they hit each sensor in turn and locate the home position.


When all the frame construction and moving axes systems are fitted together, the wiring of the electronics can begin. Again, it's not as complicated as it may sound. The electronics are modular and wiring is straightforward; when the wiring is complete, so is the home 3D printer.