Assembly Assistance for the Printrbot Simple - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 46

Note
Some Simple owners have suggested putting on the zip tie first and then
tightening it down before inserting the metal axle. This might work, but
there's also the chance that you'll tighten too much and never get the
vinyl tube to fit over the axle. When the tube is on and tightened, rotate
it with your fingers. If the metal axle rotates, you've probably got the
vinyl tubing tight enough.
When you connect the X-axis assembly to the base, you'll also get your first ex-
perience in using the small M3 nuts. These nuts are inserted into the small slot in
the laser-cut wood, as shown in Figure 3.9 . The nuts fit into the slot only one way,
but even then you may have to give it a good squeeze to fit in there. After the nut is
inserted into the slot, you'll screw in an M3 bolt to hold the motor (or other pieces
of wood) in place.
Figure 3.9 The M3 nuts go into the laser-cut slots sideways to accept a bolt.
Finish the base by attaching the right-side wood piece, and make certain the Z-mo-
tor and X-motor wires are coming up out of the rectangle cut in the center of the
top piece of wood.