Wiring Part II - Printing in Plastic: Build Your Own 3D Printer - page 339

Adding the Endstops
Your 3D printer will need three endstops, or limit switches, for a couple of reasons. The endstops
prevent your machine from moving too far in one direction and will cut power to a motor if the machine
attempts to move too far. But the main function of the endstops will be to allow your machine to self-
calibrate before a printing job begins. We'll talk more about the endstops and how they are used in the
next chapter, but for now you just need to install them. Figure 18-17 shows the three endstops and their
cables.
Figure 18-17. Three endstops, one per axis
We'll first attach the endstop to the Y-axis, as shown in Figure 18-18. This is the left side of the
machine if you are looking at the machine from the front; the endstop is sitting on the top edge of the
Upper Structural Side.