jenis crimping

Making Ethernet Cables

And other cable related wisdom.

Ethernet is based on Cat5 cable. This consists of 4 pairs, for a total of 8 lines. Each pair is twisted together in the cable, and each pair has a different twist structure. Hence why it is often called shielded / unshielded twisted pair (STP / UTP). Its vital not to disturb the twists on the cable to much - when working with cat5 only un-strip as much of the cable as you need.

There are two patterns for cat5, A and B. Because of the twisting you must use one of these. For a normal cable wire both ends in the same way, for a crossover cable wire one end a A, and one end as B. These are:

	Pins are measured from left to right with the RJ45 connector upside down, with the open end facing you. A 1. White / Green Stripe 2. Solid Green 3. White / Orange Stripe 4. Solid Blue 5. White / Blue Stripe 6. Solid Orange 7. White / Brown Stripe 8. Solid Brown
	B 1. White / Orange Stripe 2. Solid Orange 3. White / Green Stripe 4. Solid Blue 5. White / Blue Stripe 6. Solid Green 7. White / Brown Stripe 8. Solid Brown

For lots more info have a look at this wikipedia page.

To make a cat5 cable you will need:
- A length of cable. *doh*
- At least two RJ45 connectors.
- A crimping tool.
- Optional connector boots.
- Optional network tester.


Crimping Tool
Used to "crimp" - squeeze - the ends onto network cables.

A crimping tool is a must have. You can sometimes make do with one of those horrible crimping things you squeeze in a set of pliers. But I wouldn't. One thing to note here is the section that crimps the cable - its clear what way in / up the cable and jack go.

RJ45 Connectors
The RJ45 connector simply "crimps" into the cable. These can only be used once. They work by forcing a metal tooth, connected to the pin, through the insulation of each strand and into the cable. In addition another section of the clip (usually a plastic triangle) squeezes the outer insulation, stopping the cable slipping out.

This is unclamped / with no cable.

Cable Boots
Cable boots are plastic covers that sit over the network connectors and stop the cable bending at 90 degrees to the connector or stop careless people snapping the springy clip off. They are pretty simple - just remember to put them on before you crimp both ends (becouse you really feel like a muppet if you dont!).


Process of crmiping

Strip a short section of the outer core (approx 30/40mm) and untwist the pairs. Then lay the cable flat and sort the pairs into the right order so its easy to slip it into the RJ45 connector.
You dont need to strip the individual pairs! When we crimp it we will push a metal spike into the core of the cable.


Then slide the cable into the RJ 45 jack, making sure that each indiviual strand slides into the right tunnel.
At this point look from the front of the connector to make sure you can see the ends of each cable and check from the top that all the cables are in the right place as above.


Slide this into your crimping tool and squeeze (one good squeeze should be enough - no need to go mad).


Thats the cable made as below.
Its normal for the connectors to be pushed below the level of the plastic, each wall port has a springy metal strip for each connection.


And you can see how it would look in a patch connector / wall port / nic etc.

Note the springy metal strip.

Testing
Once you have completed your new cable you will want to test it. I would strongly advise that you buy one of these network testers. They cost about £7 to £10, and there is no point paying etc to get the £30 efforts - they are all the same thing.

Simply put they consist of two boxes, each of which has a row of 9 LEDs, both have a network cable connector connection. They work by testing each line in turn. If the same LED lights on both end then that line is fine. The advantage of the two box design is that you can connect a box to the end of a long cable run (ie cables in walls etc) and test it fully. You can use a short patch cable (a normal cable) to connect both ends to wall points / patch panels. Always make sure no fragile network kit is connected to a cable when you are testing