Crimp or Solder ?

[McMurdo]

solder

[TonyDuell]

Originally Posted by DonaldStott

You've got me intrigued - can you elaborate, just out of interest.

For doing it by hand, something like :

https://uk.rs-online.com/web/p/wire-...tools/0605239/

(and as RS sell the tools I guess somebody other than me uses them).

The wrapping end of the tool has a central hole to fit over the (square) pin and an offset hole that you put the stripped end of the wire into. You then put the tool over the pin and turn it clockwise until all the stripped end of the wire is wrapped onto the pin. That's it, a good connection.

There are motorised tools that make it a bit quicker, but they are too expensive for me to own (so far).

And wire wrapping seems to be very reliable. I have minicomputer backplanes (panels of edge connectors that the boards go into) that are over 40 years ol d with 10s of thousands of wirewrapped connections with no faults.

[emeritus]

I have never used wire wrap, but I remember it being extensively advertised in the technical press in the 1970's, where its reliability was stressed. AFAIR it requires special insulated wire and special square, sharp-cornered posts to wrap the wire around. As the wire is wrapped, the corners cut into and through the insulation to make contact with the conductor, the displaced insulation making a gas-tight joint, and 4 joints per turn. If for example, you make four complete turns, you will have 16 points of contact, giving multiple redundancy.

I note the hand tool costs nearly £45: I guess if you won the lottery you might be able to afford the motorised version!

[G6Tanuki]

Wire-wrap was used extensively on mainframe/minicomputers in the 1960s and 1970s - it being easier to implement on-the-fly production-changes this way than if the backplanes [which were often quite a few feet across] had been implemented as a multilayer PCB. You can think of a wire-wrapped backplane as being 'multi-layer' to an arbitrary level !

1970s/1980s telephone-exchanges also made extensive use of wirewrap.

In the context of the original enquiry, to be honest for speaker-leads it doesn't really matter one way or the other. if you were using heavily-multistranded cable my preference would be to crimp a 'bootlace' ferrule onto the end of each core and then use screw-terminals. Bootlace-ferrules do at least minimise the risk of 'escaped' wire-strands that can splay out and cause short-circuits.

My go-to for speaker-leads is 2.5mm or 4.0mm twin&earth flat mains cable. The 2.5mm is solid-core, the 4.0mm is multi-strand so it's a bit more flexible.

[Oldcodger]

From memory, wires were wrapped ,using a wire wrapping gun on Telecomms equipment frames ( permanent wiring side) as long ago as the 70's, although hand wrapping tools were available.
Organisations such as BR,where soldered joints were exposed to the elements were discontinued a lot of years ago, as the solder crystallised in frosty weather, and replaced by crimped joints. Problem crimping smaller diameter wires is that standard crimps only go as small as 1mm( red crimps, but my tool says .25-1mm ), although I've done it successfully by doubling the wire. But to be successful you need a decent ( multi crimp ) tool. And don't forget to test the crimp joint by pulling on the wire .
Looking at last post, an alternative to stop "stray ends " is to use heat shrink over the crimp and over a portion of the wire, or use crimps which incorporate heat shrink on them .

[ex seismic]

I can testify to the reliabilty of wire-wrap. We had some seismic instrumentation that used the technique for back planes and I cannot recall any failures. This was equipment bolted into the back of Bedford 4 tonners and bounced across deserts and the like in often high temperatures.

Gordon

[John10b]

Hi Donaldstott #20, I hope wire wrap technique is now clearer to you, the tool we used was spring loaded, you just pushed down and it would rapidly turn, which gave a very tight bind. It’s over 35 years since I used them. I do wonder if they still use wire wrap.
Cheers
John

[duncanlowe]

Early in my career I made a board using wire wrap, as that's what I was asked to do. Yes it was special wire, with IIRC tefzel insulation. The battery operated tool was easy to use. You pushed the end of the wire ip into the tip of the tool and it would strip the insulation locally and wrop the requied number of times before cutting off.

[cooperman]

Back in the late 70's and early 80's I worked for ICL in their factory at Winsford. They had some automatic wire-wrap machines that would would do all the pint to point connection on quite large mainframe backplanes. I think they were controlled by punched paper tape. Very impressive to watch when they were working at speed.

[John10b]

I wonder if wire wrap is still used today?
Cheers
John

[Philips210]

Hi.

I wouldn't go as far as saying it's extinct but certainly not commonly used these days. There is a good article on wire wrapping here https://en.wikipedia.org/wiki/Wire_wrap

There's a pic in that article showing a CFL lamp from the early 2010s that used a couple of wire wrap connections. In the same article, it's incredible seeing the construction of those computer boards noting the shear number of connections which must be testament to the reliability of wire wrapping.

Regards,
Symon

[John10b]

Thanks Symon very interesting.
Cheers
John

[DonaldStott]

Picture below shows some of the "floating spirals" in my Philips B3G63A before restoration - c.1956.

https://www.vintage-radio.net/forum/...pictureid=3395

Don't know how you would wire wrap a loudspeaker cable and plug?

[kalee20]

I've done a few wire-wrap joints (not for 10+ years though) in the 'day job' using a powered tool. Very quick, and just about the only way to make a joint in the middle of a maze of connections (trying to dive in there with a soldering iron is definitely a no-no).

I've also removed connections - an unwrapping tool is just a thin rod with an axial hole, with the end machined into an end blade. Putting on the connection pin and rotating, the blade picks up the wire end and starts unwrapping. The job takes seconds.

Unlike others in this thread, I used plastic insulated wire which needed to be stripped first. There are two styles of joint, the 'standard wrap' where the whole of the length wrapped around the pin is stripped, and the 'modified wrap' where less is stripped so the first 1.5 turns wrapped are of stripped wire. This does nothing towards the connection, but adds a bit of reinforcement if the joint is likely to be subject to movement as subsequent wiring is done.

Wire wrapping is still done for some 19" rack backplanes, with DIN41612-style connectors for plug-in Eurocard-size boards. With up to 96 pins, it's ideally suited!

I used manual wire wrap for logic stuff in the 80's, great for prototyping (you always get one or two things wrong) and you can un and re wrap a wire a few times before it fails (breaks). Upside down labels for ICs where available giving the pin numbers to make life a bit easier.

The wrapping tool is very finely engineered to squash the wire onto the corners of the pin and make a cold weld, these are gas tight and very reliable. You can feel the welds breaking if you unwind one by hand.

[bobreel]

Back in the 1970's and 80's I used to work for DEC on mini computers and their peripherals. Wire wraped backplanes were in most equipment. Sometimes we would have to modify equipment when an ECO (engineering change order) was issued from the States. This sometimes took hours as each pin location had to be identified, checked and rechecked. As a mistake could write off the whole machine. Back in the late 70's I had a Sony TA2650 stereo amp. I had the case off it once, and low and behold wire wrapped connetions! I was well impressed.

[Philips210]

Originally Posted by DonaldStott

Picture below shows some of the "floating spirals" in my Philips B3G63A before restoration - c.1956.

https://www.vintage-radio.net/forum/...pictureid=3395

Hi.

Yes, Philips often used that excellent method of joining wires/components. I frequently use that method when doing repairs and building projects.


Regards,
Symon