how to solder shield braid to conductor? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: June 25, 2021, 06:14:27 pm
content: What methods are there to join a shield braid to a conductor in a cable, if its not a crimp type? (i.e. soft audio)?I have been trying to cut the braid in half with ultra flush side cutters and twist it into a wire and attach it to the ground/neutral wire by twisting it together before soldering it into a solder cup, but this is successful maybe 15% of the time ... it often disintegrates seemingly randomly, its hard to dress.So I have been just cutting it so there is a nice coverage of the wire base, soldering this to make a solder ring there (hard), and soldering it to the ground with another thin wire or a solder braid, if you get a nice big cable with a good strain relief its seems OK (and this is the way I have seen it done industrially), but I am wondering if there is some tricks to not having the braid disintegrate without a solder ring and other wire. It seems as soon as I cut it, it has a good chance of falling apart.And the solder + wire method relies on the wire having some kind of insulation in it (i.e. cotton string) to insulate the insulation from the solder melting ontop of it. Its neater but you also have 2 solder joints rather then 1 solder joint.So I strip, cut all insulation and braid off to expose conductors without any shield, so its a nice cut, then I strip another 3/8 of an inch or so, so the braid is exposed, then cover the braid with solder carefully (only if the wire is covered with cotton or something), then solder the connector on and then solder another wire from the connector to the braid ring, possibly cover with heat shrink, assemble cable.And if I try to 'split' the braid I get a mess, a vacuum cleaner and a seriously poor ground. But I think they want you to split the braid some how and turn it into a wire but its like ridiclously hard. I made a 4 pin cable today and the first side I got the braid twisted into a little wire and soldered it on and it was actually pretty good and clean, but the 2nd half of the cable I attempted to do the same thing like 4 times before I lost too much cable and decided to use the solder wire extension method, no idea what I did wrong.

author: coppercone2
author_rank: Super Contributor
timestamp: June 25, 2021, 06:40:27 pm
content: this is pretty good japanese cable, I wanted to know if there is like a braid split tool or something thats more reliablethe tape impedance is funky, i prefer to direct solder itmaybe stuffing some heatshrink under the braid is a good idea to protect the conductors from heat a little bitI thought there might be some kind of tool like a cone shape that you slide it on like an arbor with slots for a cutter to try to make a cleaner cut under controlled tension or something like this, an assortment of shapes to help. I also thought dousing it with sticky liquid flux and letting it dry up a little bit prior to cutting might help it stay together before its twisted and soldered but its a messy idea.

author: TimFox
author_rank: Super Contributor
timestamp: June 25, 2021, 06:55:42 pm
content: With reasonable shield braid (and much is not), I take a sharp point, such as a carbide scriber when handy, and start (from the free end) to un-braid the fine wires, working the point back away from the free end, pointing the tool through the braid into the inside, until I reach the stripped end of the cable jacket.Then, I take the unbraided wires and twist them together to make a stranded wire. Sometimes, there is too much of the fine wires, so I cut some off to make the final stranded wire a more reasonable size.Sliding a short piece of polyolefin heat-shrink under the braid, over the insulation, is a good idea to avoid melting the dielectric when soldering.

author: coppercone2
author_rank: Super Contributor
timestamp: June 25, 2021, 07:17:26 pm
content: how long of a braid length can you typically undo ? With something beast like LMC400 cable you can undo alot, but fine stuff is hardi am trying to figure out what is considered decent for cable, because the other parameters of this cable are very nice, bendy, low impedance, fine shield, etc.I need to find metal multi conductor connectors that have a thing to solder the braid to so the shield is full but that seems rare and or expensive, I think it falls under the jurisdiction of twinax and so forth to get that level of quality at 100$ a connectorI have been finding that resistance soldering tweezers are very good for cables that are soldered, particularly when you have the wrong sized solder cup, it still allows for a very tight and decent joint

author: jpanhalt
author_rank: Super Contributor
timestamp: June 25, 2021, 07:43:45 pm
content: Quote from: coppercone2 on June 25, 2021, 06:40:27 pmA wood toothpick has never failed me. Maybe one made of titanium would work better?

author: coppercone2
author_rank: Super Contributor
timestamp: June 25, 2021, 07:53:29 pm
content: i described the tool I had envisioned, a arbor cone thats very pointy that you slide the cable through so you can tighten the braid around the cone prior to cutting to get a better cut, or something similar, maybe it can be made of metal sheet wrapped around a tube with some spacers on it, maybe you can actually undo it nicely without cutting it to some degree too if if you pull it taught on somethingif you wanna work like stewart little with tooth picks and shisakob sticks its okand yes a polished hard pick would work better then wood, but i am not asking about picks here. even with a simple pick there can be improvements made like maybe a rounded tapered oval shapeI was hoping maybe someone that deals with it alot like a avionics technician might have some professional tips

author: coppercone2
author_rank: Super Contributor
timestamp: June 25, 2021, 08:09:15 pm
content: https://www.jensentools.com/shielded-lead-wire-extractor/g/723this looks interesting

author: Bud
author_rank: Super Contributor
timestamp: June 25, 2021, 08:18:38 pm
content: I trim the braid back a little bit, wrap a few turns of a thin soft silver plated wire around the braid, and use a beefy soldering iron to fill these sleeve with solder all around. This produces a solid termination to which a lead ground wire can be soldered. The thing when soldering the sleeve is to use a hot soldering iron with a beefy tip and do it fast to avoid melting the center wire jacket.

author: coppercone2
author_rank: Super Contributor
timestamp: June 25, 2021, 08:27:58 pm
content: yeah a spring was coming to mind too, you can also press a wire there and then wrap the spring around to make it even better possibly, but its less friendly for reworkthat tool looks like its the best though because it should offer the best possible impedance and flexibility since there is no cutting if it works but I need to buy one first, and I am not sure how well it will do for multiconductor cable, it seems like you need something loose, very interesting since theoretically it might not cut any conductors at all

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 25, 2021, 08:30:28 pm
content: Personally, I never found I could tin the stuff before the core gets fully melted, and then it's a crap shoot whether it slides around in the goo and shorts out or something. Bigger problem with thin cable (RG-174 etc.).I prefer to use a small pick, screwdriver, etc. to tease the braid apart. Grab a few groups of strands going one way around, dig under them and pull up and out. They'll unthread from the braid, leaving voids. (Straighten the extracted strands so they don't tangle up on themselves.) Continue around until all of one direction are loose. Untwist the remainder. Splay everything out smooth and radial, then gather and twist, then trim and terminate however you need to (solder, crimp..).I don't think there's really a good way to make a quality coaxial joint, short of tinning the whole thing round or using a crimp. You can improve it with hacks, like by removing the jacket further back and clipping the braid into a ground clip. The multipoint grounding keeps shield currents away from the signal.Oh BTW, you could do a hybrid, where you scrunch the braid down so it kinda sticks out in a ring, then solder that all around into a bulkhead (assuming something solderable, copper or tinned steel). Will still need a strain relief, but that provides good shielding at least.Tim

author: coppercone2
author_rank: Super Contributor
timestamp: June 25, 2021, 08:35:50 pm
content: I am just trying it on multiconductor cable, not coaxial, that is a pain in the ass unless you have teflon, but I feel like coaxial is easier to unravel then multi conductor non coaxial cable thats braided, and then it can be used in a compression fitting, but only if the cable fit is good.. if you plan on filling the void with putty or epoxy because the cable is smaller then the fitting then good luck IMO

author: tpowell1830
author_rank: Frequent Contributor
timestamp: June 26, 2021, 03:54:38 am
content: NASA-STD-8739.4 has some assembly methods for this, including pictorals.Hope this helps...

author: coppercone2
author_rank: Super Contributor
timestamp: June 26, 2021, 05:41:51 am
content: :-//I bought one of those tools, I will look at the nasa tooI kind of think that not soldering this stuff can with vibration cause pretty bad shorting of the connector, it seems that it should maybe be dipped in liquid electrical tape or something to hold it together. I wonder how good heat shrink is at containing it.. I am almost thinking full tinning might be safer because it might make the shield break but it wont short anything out from disintegration

author: jbarker2160
author_rank: Newbie
timestamp: February 25, 2022, 08:50:36 pm
content: I know this is kind of an old thread, but I solder quite a few Canare cables that have the type of shielding the OP is talking about.You need to expose about 2-3 cm of braid, pick it apart on one side(it only takes about 5 seconds if you start from the cut end and work your way back,) and twist it together.If you are using a solder-cup-bearing connector, you need to tin the connector, not the cable. Then, while the solder is still "wet," lay the twisted-together shield into the puddle.

author: coppercone2
author_rank: Super Contributor
timestamp: February 26, 2022, 01:01:13 am
content: Well if I expose that much I am kind of wondering if I can unthread the cable strand by strand with a pair of fully rounded tweezers and a needle instead of cutting it, then just cut the conductors shorter. Given how well all the other methods worked, picking it apart under magnification without cutting might be an option.I kind of attempted this before but it usually ended up ripping strands.. it needs to be done slowly and meticulously, maybe with some lubricant to avoid friction on the tiny strands. .