Crimpers are tools used to insert wires into the proper connectors at the end of the cable. These are dedicated tools based on the cable type used, such as the crimper shown in Figure 22.2 below:
- Twisted-pair
- Fiber optics
- Telephone cable
- Coaxial cable
Figure 22.2 – UTP Cable Crimper
Crimping is usually the last step in the cable installment process. You connect the wires to the proper connectors only after the cable has been put in place between the two endpoints. When crimping a UTP cable, the copper connections are pushed into each of the eight wires through the insulation so that the electrical connection can be established. At the same time, the crimper is fixing the connector into the UTP plastic cable jacket to keep it in place.
Figure 22.3 – RJ45 Connector (before and after Crimping)
As can be seen in Figure 22.3 above, before the crimping process, the RJ45 connectors are not pushed inside the plastic connector case and into the actual wire. These pins are very sharp, so once you place the wires inside the connector and use the crimper to push the pins into the wires, these will go right through the insulation of each wire.
Many crimpers have a built-in wire cutter and wire stripper, so they can be considered universal tools in managing cable connectors. Before actually starting to crimp the cables, you should verify a few things:
- Make sure that you use the right type of connectors based on the cable types (check the cable specifications).
- Make sure that you properly align the wire colors with the correct pin positions (be careful when differentiating between straight-through and crossover cables).
- Make sure that you have enough spare cable at each end, as you might have to cut small portions of it if the crimping process is not successful after the first try.
A common mistake in the crimping process is cutting too much of the wire jacket, as shown in Figure 22.4 below. If this happens, you will not be able to secure the connector into the jacket and this can lead to a short life for the cable (i.e., the wires might come out of the pins if you pull on the cable).
Figure 22.4 – Common UTP Crimping Mistake (Jacket too Short)