Practical Wiring - Club Level: Twisting Communications Wiring
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Twisting Communications Wiring
03.54
| 00:00 | - As discussed in the design skills section, communications wiring and in particular CAN bus wiring is run as a twisted pair to help control any noise that might get into those wires. |
| 00:11 | It is possible to purchase pre twisted wire but its also possible to easily twist it ourselves and this means that we need to buy and keep in stock fewer types of wire overall and that can be quite a substantial saving. |
| 00:23 | This step can form part of our wire preparation process also. |
| 00:27 | I do often like to twist a large length of communications wiring and then keep it rolled up in a spool and simply cut off the required lengths as I need them. |
| 00:36 | Doing it this way also ensures that all our communications wiring has the same twist angle and that does keep things nice and tidy and uniform. |
| 00:44 | However for demonstrating the process out here on the bench, we're going to twist this section of wiring and we're gonna show you the process is very easy to do. |
| 00:54 | So the first thing we need to do is secure one end of our wire, and in this instance I've got our suction mounted movable bench vice here, clamped onto our bench and I've got our wire mounted at this end there. |
| 01:05 | We then need to comb out all our wiring and make sure it's running nice and parallel and there's no crossovers in it. |
| 01:14 | We're then going to get a handy shop drill and we're going to put the other end of our wires that we've combed out and have the same amount of length on, into our drill chuck. |
| 01:27 | Now we're gonna tighten this drill chuck down very tight and that is actually going to damage this end of the wires here so you do need a little bit of extra length if you are undertaking this on some sections of pre cut wire for your harness. |
| 01:41 | I'm gonna crank down on this now as what we definitely don't want to happen is for these to pull out when we're part way through the twisting process. |
| 01:49 | So then we wanna get a bit of tension on our wires there, I'm gonna put my drill in the forwards, the clockwise direction and keeping a bit of tension I'm simply gonna pull the trigger and twist these wires together. |
| 02:08 | Now the tension that you keep on the drill and on the wire here is actually the key to this process in ensuring that you get a really nice even twist along your wires here and you don't have any errant stray cross overs. |
| 02:21 | What I've done here and why I'm keeping this under tension at the moment is because if I was to release the tension, this would spring back into a big bird's nest which is not what we want. |
| 02:31 | That's because I've actually over twisted this wire. |
| 02:34 | And I've done that because I can then reverse my drill and we can reverse that twist back to get our desired amount of twist on the wire, that's also going to release the tension and mean when we release the wire from our drill chuck it's not going to spring back. |
| 02:49 | So I'm just gonna keep that under tension and slowly untwist the wire, to get back to our desired twist length. |
| 02:58 | Now there is of course the question then about what is our desired twist length? When you're twisting wire with this method what you're aiming for is a lay length of between eight and 16 times the diameter of the wire. |
| 03:10 | Now when I say lay length, that refers to the length, the distance that the wire runs down the linear length of the harness as it makes one complete revolution. |
| 03:20 | So you want that to be between eight and 16 times the diameter of the wire here. |
| 03:25 | It is quite a broad range and what you will find after you've done this a few times is that you'll get an eye for what is a nice twist angle on the type of wire that you're working with. |
| 03:34 | So I'll just remove this from my drill chuck here and you can see it hasn't sprung back into a big bird's nest, it's stayed nice and tightly twisted, and that is gonna be a good section of CAN bus communications wiring, we're gonna be able to run through the rest of our harness. |
