RepRap for Science—How to Use, Design, and Troubleshoot the Self-Replicating 3-D Printer - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 151

FIGURE 5.54 Mounted z -limit switch.
The x -switch is triggered by the x -carriage. The y -switch is triggered by the corner of the
y -frame (blue) and the z -switch is right beneath the flexible arm (yellow). Put an M3 and two
nuts on the flexible arm to enable you to do fine control of the z -switch.
5.2.11 Power supplies
You can purchase a power supply specifically for your RepRap, but chances are if you are in
either an educational institution or an industrial lab, there are a plethora of appropriate power
supplies available from old computers that are being discarded. Cannibalize an old computer
or buy a power supply that provides a minimum of 15 A at 12 V. After the power supply is
completely unconnected, cut of the ends of all the black and yellow (12 V) supplies, group
them and solder together (as seen in Figure 5.55 ). Take the yellow and black bundles and ex-
tend with wire by soldering. Then plug these power lines into the Melzi Board. You will not
need the other leads, but leave them on to both prevent shorts and leave room for expansion
in the future (e.g. adding a cooling fan).