Assembly Assistance for the Printrbot Simple - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 51

Figure 3.13 This assembly allows the hot end to move backward and forward.
Set the Y-axis Mini-Assembly 2 aside with Mini-Assembly 1, and next you'll
tackle part of the Z axis. The Z axis differs from the X and Y axes in that it won't
be using fishing line. Instead, the Z axis requires the use of the 10” lead screw with
a piece of vinyl tubing zip tied to it, as shown in Figure 3.14 .