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Practical Wiring - Club Level: Splicing to Shielding Braid

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Splicing to Shielding Braid


00:00 - When we have run a signal through our harness using shielded wiring, we will need to connect a short length of standard wiring to the shielding braid at one end in order to make a ground connection.
00:10 This allows any noise picked up by the braid to be drained away to ground and not propagate through to the wires underneath.
00:17 It's very important that we only make this ground connection at one end of the wire however, as if we ground both ends of the braid it will almost certainly violate our star earthing rules.
00:27 There are two common methods used to connect to the shield braid, the selection of which depends on the materials on hand and the space that you have available.
00:35 The first one that we are going to look at here is using a standard open barrel crimp terminal to make a connection to that shielding braid.
00:43 Now this is going to involve stripping back a section of the shielded cable insulation to expose the braid underneath, teasing a hole in it and then withdrawing the wires inside out through that hole and then pulling that shielded braid tight again, essentially turning it into another piece of wire that we can make that crimp connection to.
01:04 So we'll show this process in detail now.
01:06 The first technique we're going to look at involves using a standard open barrel splice terminal to make a connection to our shield braid in our wire here.
01:15 To to this we're going to have to strip back a section of the outer jacket of our twisted shielded pair wiring here.
01:23 Now you can get specific tools for doing this, they're call coaxial ringing tools, and they do do a very good job however I don't typically have one on hand, and I find a standard razor blade knife also does a very good job, you just wanna make sure that you've got a new sharp blade installed in there.
01:40 So what we wanna do is we simply want to score a ring around our wire here and often you can do this by rolling the wire on the bench as you're holding you knife next to it and if you do cut through the cable jacket, it's not gonna be the end of the world as you're not likely to nick the wires underneath as the shield jacket will actually do a pretty good job of protecting them.
02:03 So we'll just score around that and then to expose our braid underneath we simply bend the wire and that shielded jacket is going to break along the score line there.
02:15 So you can see we've got a nice break in our shielding jacket here.
02:20 Now we're going to score along the length of the wire and remove the end of that section, so this is exactly the same process, sometimes it can be a little bit tricky just due to the shape of the cable, with the twisted pairs underneath.
02:35 But if we score along that we can get our fingernail in there and simply remove that outer jacket like so.
02:43 When we get to this point, what you now need to do is press this outer shield jacket, you want to move it backwards which is going to bow it out at the end here.
02:51 So we'll show that, pressing that backwards and you can see it has bulbed out at the end here.
02:57 Now using a handy pick tool like the one I've got here, what we now want to start doing it teasing open a hole in our shielded jacket which should be reasonably easy because we've pushed it back and bowed it out to give us a little bit of extra room to work with.
03:12 So you can see I'm opening up a hole here and we can see our cables, our inner conductor strands inside there.
03:21 What our end goal here is, is to actually get those inner cables out of this hole, leaving our shielded jacket reasonably intact and essentially turning it into another wire that we can make that open barrel crimp connection to.
03:34 So to do that what I like to do is get my pick tool underneath one of the wires here and actually insert it in between the two of them, trying to keep any conductor strands below my pick tool while I'm doing this, which sometimes is a little bit easier said than done and you might need a couple of bites at it like I'm taking here.
03:54 Get that in place.
03:57 And then inserting that pick tool through, because it's tapered it's actually gonne start pulling that wire through that hole and I can simply get that all the way through like so.
04:09 Now it's now uncommon for your shielding braid to get a little bit abused when you're doing this process however you're still gonna have plenty of material there to make a good open barrel crimp connection to so don't stress about it too much.
04:22 the next part of the process is very much the same, we're just gonna get our tool underneath this other wire, avoiding any of our shielding braid strands there, and also pull it through that hole that we've made.
04:36 Like so.
04:39 I'll pop that pick tool to one side and we can get our shielded braid here and we can actually pull and straighten that out and tidy everything out.
04:47 Grab those errant strands and get them as part of the bundle as well.
04:54 Now that we essentially have three wires here at the end of our cable, we're gonna make and open barrel crimp connection to our shielded braid here and we're gonna do this using a completely standard brass open barrel splice.
05:06 Now splicing like this is a technique that we've shown in a couple of other stages of the course, so not gonna go into it in a huge amount of detail.
05:12 But I'm just gonna get my open barrel splice at the end of my crimp tool here, get everything lined up and get my other section of wire that we're actually going to crimp to the shielding braid.
05:24 Now this is just completely standard wire, in this instance it's 22 gauge green TXL wire, but it is just completely standard wire that's going to head down to either a power grounding point on the ECU maybe or a power grounding point, also typically the chassis is used as well.
05:40 So our open barrel splice, as much as we've done with many other sections, we're gonna get this installed through our splice here without any conductor strands poking out the side and get our other wire in there as well, and apply pressure to our handles and perform that splice operation.
06:06 Rightio we can see that's been a nice successful crimp join.
06:10 Everything's really nice and tight in there but we do have this little bit of extra material sticking out the side so we're simply going to trim that off, just to keep everything nice and tidy.
06:22 So you can see there we've got a good open barrel crimp connection onto our shielding braid that's typically going to get flipped around like this, and that's going to leave our standard conductor wire heading off in the same direction as our cable which is more than likely what we want if we're gonna be connecting it to a power ground pin of the ECU or a star earthing point.
06:44 Now we've got a section here that was going to be insulated right in the middle of our harness which we obviously can't have so I'm going to use a small section of raychem SCL to heat shrink that closed so we'd get a section of that, get it in place there, and this is gonna give us a good amount of strain relief on that join as well.
07:09 So I'll just get my heat gun out and turn it on and we'll shrink that down.
07:16 Right so we've got that shrunk down there and that's gonna give us a really nice tidy crimp connection to that shielding braid.
07:22 Everything once that ECL cools down and goes rigid is gonna be really well strain relieved and that potting compound is gonna keep everything in place as well.
07:31 So that's the first technique we're gonna show you is how to make a really good reliable connection to that shielding braid.
07:38 The second technique is going to involve using some raychem solder splices and in the professional motorsport world, this is going to be the preferred technique, however I do find it can be a little bit trickier and also can take up a little bit more space so you're probably going to want to practice both these techniques so you've got them in your toolbox of techniques and you can determine which one you're going to need at build time.
08:01 So the second technique we're going to show you is going to be using one of these raychem solder sleeves.
08:07 And these are actually a heat shrinkable product and this red section in the middle is actually a low temperature melt solder and this outer barrel will shrink down, these two dark blue sections on either end are sealing beads.
08:23 So they're going to melt and flow out, much as our raychem SCL dual wall potting compound does.
08:29 They're going to flow out onto our wire and seal it and our solder sleeve section in the middle here is going to melt and flow onto our exposed shielding braid and we're going to have out ground wire inserted from one end as well.
08:42 Now these are red for a very specific reason, they come in different colours for different sizes.
08:48 Red here is actually the smallest so it's gonna be the correct for this application.
08:52 You then go to a blue and then to a yellow, the larger sizes you get.
08:55 And you know your solder operation is complete when actually all the colour is gone away.
09:01 So that red will actually disappear and you'll just see the solder underneath.
09:05 So the process is going to begin a very similar way as to our last one, we're simply going to score around the outside of our wire here to then break away that insulation and expose our conductor strands.
09:21 Then scoring down the length and getting that off there with our fingernails.
09:30 But this is where the process gets a little bit different.
09:33 We are still going to push backwards on this to bulb out our braid here, but we're actually going to keep pushing backwards and we're going to try and fold that back onto the outer cable jacket here because this is where we want to connect to and we need to leave a section of wire here that we're probably going to end up crimping a terminal onto.
09:59 So we can get that pushed back and this is where we're going to make our connection and we can get our solder sleeve on that section and line up the red solder barrel there with our exposed section of conductor braid.
10:20 That is all in place there.
10:22 So you can see I've got our red solder section lined up with the conductive braid there and I've still got a little bit of wire poking out at the end here.
10:32 In situation you might actually strip back a wee bit more insulation to give yourself a little bit more room to work behind the connector.
10:40 So I've got my section of standard wire here which I'll just strip a wee bit of the end away from.
10:48 We then insert this from the end here and we want to line up those copper conductor strands once again with that red solder sleeve section.
10:58 So we can get that in place.
11:00 And because these are the smallest solder sleeves, things do get a wee bit tight, but that also does mean that we're using the correct size for the application.
11:10 So I've got everything lined up and in place there, we're gonna go ahead and get this under the heat of our heat gun.
11:15 I've got my heat gun set to about 450 degrees here which is actually above, quite a long way above the recovery temperature of these sleeves but I find it a really good temperature to use to make sure that they recover nice and quickly and we do get a full melt on that solder which once we've completed this we'll look at in detail and I'll show you how to know that you've also got that.
11:38 So I'll turn my heat gun on here and we'll get this shrunk down.
11:47 Rightio so we can have a look at this and see what we've got.
11:51 So what we're looking for to know that we've got a really good successful solder melt and that is going to be a good successful join, is some of our potting compound or our sealing compound has squeezed down the end meaning that it is making a good seal to the wire underneath.
12:05 And we can't see any more red colour in the centre here.
12:09 It's all melted and flowed away and what we can see actually looks like the shield braid underneath but it has been penetrated and bonded to with that solder.