Uncrimping - Page 1
Forum section: electronics / general

author: grifftech
author_rank: Frequent Contributor
timestamp: March 02, 2016, 05:27:07 am
content: How to reuse crimp on tabs

author: quarks
author_rank: Frequent Contributor
timestamp: March 02, 2016, 06:42:01 am
content: A good crimp is one of the best (if not the very best) connection you can get and it is not possible to "uncrimp" it.I would not recommend it, but the only way (I can think of) to reuse a crimped connector is solder on top of it

author: TerraHertz
author_rank: Super Contributor
timestamp: March 02, 2016, 12:09:57 pm
content: Quote from: quarks on March 02, 2016, 06:42:01 amYes it is. A small sharp chisel and hammering can split the ferrule down one side, and open the tube enough to release the wires.QuoteAfter being split and opened up like that, you can squeeze it roughly closed over a new wire then solder it in place.

author: quarks
author_rank: Frequent Contributor
timestamp: March 02, 2016, 01:10:14 pm
content: Quote from: TerraHertz on March 02, 2016, 12:09:57 pmOops! Do you really use and recommend such a botchy solution?In my opinion I gave the only proper recommendation I know of. And that is, you never should reuse a crimped connector. They are made for exactly one time crimp and if this crimp fails you should always use a new crimp connector. Also a good crimp, which I am referring to, will make a cold weld and the material does workharden in this process. So if you try to open it, it will weaken and most likely break. To avoid this you could heat it up and soften it again, but I do strongly suggest not to use the method.

author: nanofrog
author_rank: Super Contributor
timestamp: March 02, 2016, 06:17:52 pm
content: Quote from: quarks on March 02, 2016, 01:10:14 pmExactly.Quote from: quarks on March 02, 2016, 01:10:14 pmNot just work-harden, but all of the strands will be welded to one another, not loose as they were when stripped. Thus a proper crimp results in a single contiguous mass of metal if you examine the cross-section where the crimp pressure was applied.

author: TonyPh
author_rank: Regular Contributor
timestamp: March 02, 2016, 08:28:05 pm
content: Don't do it.After removal the crimp terminal is only good for the bin, as are the crimped wires.Easier just to cut the terminal off and put a new one.

author: TerraHertz
author_rank: Super Contributor
timestamp: March 02, 2016, 11:11:06 pm
content: Ha ha. I knew that would give all the perfectionists heart attacks. And maybe the OP intended that too.But, my comment is still true. You *can* reuse crimped lugs.However no one is suggesting actually crimping them a second time. Only reusing them as solder-on lugs.Yes, the metal work hardens with the first crimp, but nowhere near enough to be near fracturing due to a little more flexing from opening up slightly, and re-closing to better fit the wire for a good solder joint.Btw, it's break not brake.As for reheating - no. To anneal the copper you'd have to get it hot enough that the surface tinning would burn. Then you couldn't solder it.Also, the only scenario in which anyone is likely to need to do this is for private use, where you urgently need to attach a wire to a terminal, you do NOT have any suitable new lugs, but you do have something suitable in the junk box, except that it's already crimped to some bit of wire that isn't suitable. And possibly the lug in question may be large, like for welding cable, and even if the shops happened to be open then it's still a drive to get one and not insignificant cost.So, hacked and soldered it is.Yes, I've done this more than once. Only for unusual size terminals, since I have stock of all the common ring lugs. Re-shaped neatly, and sleeved with heatshrink, a reused one can look as good as a new one.For large cable connections, another improvisation is to beat a bit of copper water pipe into the appropriate shape, then solder it on.Of course I'd never do such things for anything commercial.

author: nanofrog
author_rank: Super Contributor
timestamp: March 02, 2016, 11:55:59 pm
content: Quote from: TerraHertz on March 02, 2016, 11:11:06 pmYou're proposal = too much effort actually.I keep terminals on hand, so it's easier to snip off the bad one and crimp a new one on.Worst case however (need to recycle a previously used terminal), cutting the wire a bit farther back and either crimping a butt splice to attach it to a new piece of wire or making a lineman's splice (wire - wire solder joint), is something I'd do in a pinch if there weren't a better solution.

author: Brumby
author_rank: Unknown
timestamp: March 03, 2016, 12:33:47 am
content: I've done it in a couple of situations where time and the lack of new connectors dictates.The crimp itself is left alone. The wire coming out the back is stripped, the new lead attached, soldered and covered with heatshrink. Run the heatshrink over the crimp and it looks neat. Do some careful twisting of the strands before soldering and it's not immediately obvious what's under the heatshrink.Of course, a new connector is quicker - but when you don't have one ....

author: vk6zgo
author_rank: Super Contributor
timestamp: March 03, 2016, 01:51:51 am
content: If you are stuck in the bush 1500km from the nearest source of the correct crimp lug--the first 250km of that being red dirt,you may change your mind about re-using them!If it comes to crimpcoaxconnectors,some lend themselves to re-use.Cheapo PL259 crimp connectors are very easy to do this with,if you can source some tube to use as crimp sleeves.