First Print with the Simple - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 92

Figure 5.12 You can move the hot end nozzle in small or large increments.
To use these controls correctly, you need to determine the direction that a motor
will move the print bed or nozzle when each button is clicked. You can do that
easily enough using the 0.1 or -0.1 buttons for each axis (or maybe the 1 or -1 but-
tons). For example, if you click the -1 button for the X axis, the print bed moves
1mm to the right. If you click the -10 button for the X axis, the print bed moves
10mm to the right. If you click the 10 button for the X axis, the print bed moves to
the left.
Similar experimenting with the Y axis tells me that the negative buttons (-0.1, -1,
-10, -100) move the nozzle forward, toward the front of the print bed. The posit-
ive buttons move the nozzle back, away from the front of the print bed. For the Z
axis, the negative buttons move the nozzle closer to the print bed, and the positive
buttons move the nozzle up and away from the print bed.
As you can see, by properly using these buttons, you can move the print bed and
nozzle in such a way that the nozzle's tip is placed in the correct starting position
at the front-left corner of the print bed.