Assembly Assistance for the Printrbot Simple - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 55

Figure 3.17 The lead screw will control the up/down movement of the hot-end.
Next you'll insert two additional 6.5” metal rods through the Y-axis bearings. The
same as with the X axis, you take the Y-axis Mini-Assembly 2 (shown back in
Figure 3.13 ) and attach it to the Y-axis Mini-Assembly 1 with zip ties around the
metal rods. Make certain these zip ties are as tight as you can get them - the tighter
the better. And while you're at it, go ahead and tie a small knot and secure it with
an M3 bolt and nut to the inside of the long Y-axis piece, as shown in Figure 3.18 .
(In Figure 3.18 , you can also see the zip ties holding the longer Y-axis assembly.)