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Old 25th Nov 2018, 8:49 pm   #1
Al (astral highway)
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Default IC wire-wrapping... who has an old kynar-strippping tool going?

Hi,

I came across some old boards from the IC wire-wrapping era the other day. I looked up the technique in The Art of Electronics and see that some truly complex boards were built up using this technique.

Does anyone by any chance either have available or know where to get a tool similar to those used at the time to strip kynar wire?

I use the soldering iron method but if there's a way of getting perfect lengths to measure by using a bespoke tool, I'd love to.

I'm also really interested in anyone's memories or experience of this era.

Cheers!
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Old 25th Nov 2018, 9:02 pm   #2
G6Tanuki
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Do you need to strip it? I remember that some 1960s/1970s early electronic telephone exchanges used wrapped 'backplanes' where the ends were unstripped, but the wrap-gun applied enough torque that the sharp edges of the pins cut through the insulation to make the contact. The big thing being that the displaced insulation round the point where the wire and pin made contact provided a gas-tight seal to avoid corrosion down the line.
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Old 25th Nov 2018, 9:10 pm   #3
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I used to be involved in naval instruments in the 1970s and wire wrapping was frequently used on backplanes. It was always cut-strip-wrap and very reliable, quick and easy to repair and modify, given the correct tooling. Logic speeds were low in those days though. Prototype or one-off boards were also often wire wrapped, using ic sockets with long legs and discrete components in carriers.

Ken
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Old 25th Nov 2018, 9:17 pm   #4
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Quote:
Originally Posted by G6Tanuki View Post
Do you need to strip it? I remember that some 1960s/1970s early electronic telephone exchanges used wrapped 'backplanes' where the ends were unstripped, but the wrap-gun applied enough torque that the sharp edges of the pins cut through the insulation to make the contact. The big thing being that the displaced insulation round the point where the wire and pin made contact provided a gas-tight seal to avoid corrosion down the line.
That was my understanding, too- there were some pretty exacting users of some fearsomely busy wire-wrap backplanes and "gas-tight joint" was part of the appeal of unstripped wire, I recall it being said that the wrapping process typically produced 40-odd connections per joint for reliability. I did have some hand-wrapping tools but unfortunately I would have let them go long ago, I never saw myself doing that sort of thing again!
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Old 25th Nov 2018, 9:36 pm   #5
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Is this the item you need, modified wire wrap and stripping tool. I used these on mini computer back planes and logic boards. Did repairs not manufacturing so I didn’t require a power wrap type.
Not cheap unfortunately.
https://uk.rs-online.com/web/p/wire-...tools/0544005/

Just had a look in my toolbox and at the bottom were two. If any use to you PM your details and I will put one in the post.
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Last edited by Nuvistor; 25th Nov 2018 at 9:46 pm.
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Old 25th Nov 2018, 9:56 pm   #6
ian_rodger
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

We also used various bought in precut/stripped lengths of wire for prototypes. I've had a look but my wire wrapping tools are not to be found. The "Heller" self adjusting type of stripping tool was also supposed to be capable of this but I never found them to be as useful as the simple slotted blade type tool. I did find a pack of pre-stripped wire dated 1979 in my search - see photo. If its any use to you you're welcome to have it.
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Old 25th Nov 2018, 10:05 pm   #7
Nuvistor
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I thought I had some precut wires and also a small reel, but I could not see them in the tool box. The clear tube with red ends and blue cut lengths, brings back a few memories.
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Old 25th Nov 2018, 10:13 pm   #8
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I have a Kynar stripping tool at work which does the job perfectly, will get details and a picture tomorrow.

Cheers,

Kev
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Old 25th Nov 2018, 10:43 pm   #9
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I first started work in 1983 for a company promoting the use of microprocessors. We used to prototype some pretty complex boards using wire wrap. The stripping tool we used was a Hoffmann 72850, 0.25mm wire version; search the web for images.

I don't know if these are still available but imagine they would be expensive. We used an electric wire wrapping gun by Vero, I seem to recall, as well as the manual wrapping tool.
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Old 25th Nov 2018, 10:49 pm   #10
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I have one of these, I think it is a tandy not been used in years,
just tried it and still OK, think I bought it when I had a
NASCOM 1 COMP.
Simple to use, you just put the tip over a pin or component
and twist clockwise about six turns shove switch to cut and turn once for
a nice job.
there are lots on the net they now use them fo making Jewellery.
hope this helps
gezza123.
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Old 26th Nov 2018, 6:14 am   #11
TonyDuell
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I use the little 'CK' brand stripper as here :

https://uk.rs-online.com/web/p/wire-strippers/1201945/

(You need to buy the right one for the size of wire that you are using, so read the datasheet from that page first).

I've used it for modifying/repairing/making DEC backplanes with never a problem.

I have never trusted wrapping without stripping (I borrowed one of said hand tools years ago, the lender said it never worked reliably, and I had the same problem). All the backplanes in my minicomputers had the wire stripped before wrapping too. Some are over 40 years old and still reliable,
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Old 26th Nov 2018, 11:55 am   #12
dominicbeesley
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

I use something like this https://uk.farnell.com/metcal/wsu-30...tool/dp/441089 - they weren't £30+ when I bought it though! Mine is in a gold anodised finish and it's not "modified".

I also use an electric wirewrap gun that ac/hl generously gave me - which gives fewer blisters!
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Old 26th Nov 2018, 12:16 pm   #13
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Hi,

CK3756 as posted up by Tony. Works very well.

Kev
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Old 26th Nov 2018, 2:23 pm   #14
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Thank you all:

Ian, Frank, (Nuvistor), you have a PM, thank you!

Gezza123, that’s interesting. I have a little dispenser with enamelled wire on a reel at the end like that. I’ll look into your type.

Kev and Tony — interesting tool , too , thank you.

Dominic -that sounds like the gold standard ! I’m a little bit jealous !
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Old 26th Nov 2018, 2:42 pm   #15
Nuvistor
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

It is parcelled up, I have been out walking this morning so I am not moving again today, it will get posted in the next few days, hopefully tomorrow.
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Old 26th Nov 2018, 2:45 pm   #16
Al (astral highway)
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

G6Tanuki...

‘..do I need the wire stripped?’: Interesting question. Sure, if I were wrapping the wire using the original technique , then you helpfully explain why that wasn’t necessary (I didn’t know this, by the way -really interesting)

But I’m not actually wrapping around pins as I’m using contemporary fast ICs with nano-second rise times, so soldering to SOIC devices under a magnifier.

The question arose because I want the shortest, neatest, point-to-point technique. I had hoped to use ‘solderable’ enamelled wire at one stage, using a min-dispenser with a reel at one end - but this is less ‘solderable’ than described !

I like Kynar wire for digital work but stripping with a soldering iron is messy and creates residues that will shorten the life of the tip.

Part of my reason for posting is also curiosity and wonder for the ingenuity of this mass-market technique belonging to a past era!
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Old 26th Nov 2018, 2:46 pm   #17
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Quote:
Originally Posted by Nuvistor View Post
...it will get posted in the next few days, hopefully tomorrow.
Thank you, Frank!! that’s brilliant !
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Old 26th Nov 2018, 2:49 pm   #18
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Ambientnoise- that sounds like a fascinating experience - the technique was clearly in high -standing if it was battle -proof and could be used on the high seas! Difficult to envisage a more demanding environment !

I imagine the ‘surface mount ‘ aspect of the technique made trouble -shooting / diagnostics faster in the event of a failed component or whole circuit board ?
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Old 26th Nov 2018, 2:58 pm   #19
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Al, yes, it was indeed a fascinating time when lots of new developments were coming through and the height of the Cold War ! I should have mentioned that all the wrapping was “modified”, that is a couple of turns of insulated wire then 3 or so turns of stripped wire. The insulated bit gave the vibration resistance. In extreme cases, the wrapped backplane was potted but experience generally showed this to be unnecessary. The tooling was handheld and fed from a reel.

Ken
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Old 26th Nov 2018, 3:08 pm   #20
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Default Re: IC wire-wrapping... who has an old kynar-strippping tool going?

Yes, I have one of those 3-in-1 tools which does the modified wrap (puts a turn or so of insulated wire round the pin). I made a couple of 9-slot DEC backplanes using it (and serveral other things) with no problems. It's not much slower than an electric tool I found.

But it's a lot easier to strip the wire with that little CK tool than the blade in the 3-in-1 tool.
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