crimping to braid ? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: January 21, 2021, 08:45:20 pm
content: So if you want to crimp to RF braid, is there a solution other then soldering to a copper washer and using a nut to tighten?(the one that looks like soldering wick).

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 21, 2021, 09:36:04 pm
content: Not clear what you want to do. Common to crimp braid into a lug and screw that down. Also common to solder.

author: coppercone2
author_rank: Super Contributor
timestamp: January 21, 2021, 09:44:03 pm
content: how do you know the CSA of braid to choose the right connector?Can you just roll it up and measure it like a wire and get good reliable results going by a AWG table? I.e. cut off 2cm, cut it length wise and then roll it up tight and measure with caliper. Then use 22-12 AWG barrel crimps. I mean even with stranded wire, you are supposed to measure only 1 strand and then use math to get the true copper CSA. Granted with yellow blue red crimps, the range is pretty big.Since its woven and not parallel or just lightly twisted I was not sure the crimp does a good job or if its too puffy or something. I don't have one to measure but I am trying to decide something in the design stage right now for ordering parts. I am worried it will not be reliable or stable.I thought maybe... its better to fill the braid with stripped wire, then crimp it to that wire gauge + 1 or something? So you are crimping a fairly solid core. I assume you should not try this with single strand wire and you should choose multi strand wire for filling the braid at the termination, if you try it this way. What strand count is good, higher = better, since it is similar to the braid itself (very fine wires), or does that just cause more trouble?I assume the only connector that makes sense with a braid is a big lug, putting it on a fast-on seems a little silly.Should it maybe just be clamped down in some kind of nickel strip sandwich which is then screwed to something (custom part)?

author: Kjelt
author_rank: Super Contributor
timestamp: January 22, 2021, 07:17:12 am
content: Theory and practice.The diameter of the braid should be given by the manufacturer but that is lost.I just did a similar job but then 100 times bigger with litzecwire for grounding my cnc machine with 35mm2litze. I knew it was 35mm2but no way it would get put in a 35mm2crimpplug without proper tools.So than get back to practice take a couple of plugs with different diameters and not only the red blue and yellow ones and starts with the smallest one and then go bigger till you are able to make it fit. Use a small testpiece of the braid. Crimp and test with softly pulling if it is really really tight. Then saw the crimp without too much force across the diameter and look under microscope there are no room/spaces left in the crimp, eg it should be one metal chunk.

author: coppercone2
author_rank: Super Contributor
timestamp: January 22, 2021, 07:53:18 am
content: Hmm, I think you are supposed to like sand it down after you cut it and then acid etch it, I thought it was more complicated then that, because the saw might burnish? gall? it and make it look solid

author: Kjelt
author_rank: Super Contributor
timestamp: January 22, 2021, 08:30:07 am
content: Perhaps that is needed with small connectors, the ones I used I was happy I was through them

author: coppercone2
author_rank: Super Contributor
timestamp: January 22, 2021, 08:56:25 am
content: I think its supposed to be lapped actually, so stuff does not get pushed into any possible gaps as you are sanding (i.e pushing stuff down hill into a hole, rather make sure that you are cutting it over the hole and having acid clean it up). Just worried it might give you a false sense of security if its safety related. Granted if the machine is built right it should probobly not rely on complex digital stuff for safety (be noise immune enough) and the safety bond should not go through a braid so it should just malfunction and give you worse parts or whatever it does. I suppose it might be good enough. A little worrisome about medical equipment, I suppose there should be a standard for this, for people that need it.

author: geggi1
author_rank: Frequent Contributor
timestamp: January 22, 2021, 09:16:32 am
content: Stick it in a lug that fits and solder.The thing about braid is that because it is a class 5 conductor (hair thin) and it is thicker than its electrical cross section and will normally require a lug that is one size up compared to the real cross section. Because of this you will get te required compression in the lug when using a crimping tool.There is two ways of doing this.1. Tie a few wraps of a strand around the braid to get a round shape that fits in a lug solder and crimp the normal way.2. Tie up as described in 1. stick the braid in the lug and then solder everything. Remember to use enough heat to get the solder to flow properly. It can be smart to preheat with a gas tourch the lug prior to soldering.There is an last one way but that is just to combine 1 & 2.