Introduction to Wire Wrap

Wire Wrapping is a technique of connecting prototype electronic circuits without soldering. It uses a special wire and tool to tightly wrap bare wire around the sharp corners of square connecting posts forming a strong connection. The technique was widely used in developing person computers but is seen rarely these days. Still, knowing how to wire wrap has it's uses today and is an interesting part of hardware history.

[alanb]

Wire wrap was and still is great for trying things out while being more reliable than breadboards. The wire we used to use was pre-stripped, there were tubes of various lengths. A lot of it was heavier gauge than the 30 gauge shown here (I recall 24 gauge being popular, this was well before PCs). There were three types of tips for the wrapping guns. One was the "modified" wrap as shown in this video, which had one wrap of insulation, that was best. There was also the regular wraps that had no insulation wrapped. There were also some special tips that could take the insulated wire (no stripping) and would strip and wrap at the same time to speed up the work. The little blue tools shown here were the first that were "affordable" for us home hobbyists. The Radio Shack tools that I purchased were defective, they damaged the wire while wrapping it so the connections were not reliable. But the OK Machine and Tool company came up with these WSU-30M tools (wrap, strip, unwrap, 30 gauge modified wrap) and while the real pro tools were hundreds of dollars these were about 25 bucks. The pro wrap tools didn't even have unwrap, they sold another tool for that (and a separate tool for stripping as well), and it was not cheap either. There were also CNC wire wrapping machines, I was involved in maintaining some of the old software that was used. They would take the net lists and compute the best routes to run the wires, and the layering to use only 2 connections per pin and minimize rework when wires needed to be adjusted, and make a paper tape. Then the CNC machine would read the paper tape and move a pointer with 2 motors in x, y that would show the operator and guide the tool tip where each wire needed to start and end and indicate how long a wire to select. This dramatically sped up the wiring process and reduced the errors. There were service companies that you could ship the netlist to and they would wire it up for you, much like PC houses today. I think it was Bell Telephone that showed the gastight connection at the sharp corners of the pin were more reliable than PC boards. A good wrap had about 10 turns, so 40 gas-tight connections in parallel. It is a little bulky but it is still a good way to make a prototype that is reliable.

[new-knowledge]

I recall way back in time when I had to construct a complex board that required a ton of wire wrapping. Got it done, but the board seemed to have a problem. Then my boss came on over, grabbed the bundles of wires, and pulled them apart, thus making the board look like it was a complete mess on the underside. And then the board worked just fine. There had simply been too much cross talk from wire to wire, so pulling them apart did the trick.

[headmetal]

I did laugh a little, because I found some of these Headers with long pins in my stuff, and now I know why they are so long :D Thanks a lot, Bill, to me you are an inspiring person and enginieer, and as a student in electrical engineering I love to learn things like these. Greetings from Germany!

[psyfertech]

very interesting that this technique was used with circuit boards i had no idea, we use it in the telecom industry to this day mostly in our central offices on the MDF's where we run our jumpers from the line equipment or dslam to the cable side, it is a great way to make an extremely reliable and long lasting connection, what really blows me away is the back side of the distribution panel for the cable leaving the co is also wire wrapped on and they have been that way in some co's since probably the 1960's so that goes to show just how reliable it is

[fabriziodutto]

WOW! Lot of work! When I was young, one of my first job was to work for a Phone company. We usually wire the cables to a chassis, solder them and put some epoxy resin, to make them airtight. LOL in the very first board you handle over the camera, the first thing I've noticed was a bent pin :-) Thank you for sharing.

[bobadams]

Years ago I worked in a metal finishing shop and gold plated millions of wire wrap pins along with other assorted connectors.

[VincentBanagas]

Best wire wrapping video out there. Would love if you could do more such as different techniques for creating a wire wrap circuit.

[CraigHollabaugh]

I still have my 30awg wire spool and tools from my IBM co-op nearly 40 years ago. These are my prized tools that are hidden away, they include EREM 502E 30 awg only wire stripper and Dumont Tweezers Style 00. Back then, I was quite handy with blue wire mods. Thanks for run down memory lane Bill.

[tanpham]

I really miss these good old days when I had to use wire wrapping for my uni projects (1985-1988).

[brianholmes]

Love this video. I still wire wrap from time to time. So fast, and surprisingly reliable.

[MikeJonesAdventureDogSoftware]

This brings back memories.. I use to be a tech doing this day after day.. 
I would also build boards with twisted pair to reduces the cross talk for the high speed design work. Then also the burn enamel wire work too. I did this for boards I need to work for longer periods. There are no pins that could accidentally short together.  Also avoid daisy chaining problems, when you had to undo something. Thanks

[AnthonyFrancisJones]

Excellent! I had for many years what I think was the backplane of sockets for a DEC PDP and it was a sea of pins and wire wrap!

[johnwilliams]

Lost count how much wire wrapping I did on "bins" when I was a Wireman. Brings back memories.

[daveb]

Thanks for the video, interesting and helpful. Another tool in my toolbox, for future projects.
I just noticed that this video is from 9 years ago ... but it's still relevant. Thanx

[jayrenner]

Should add that this method produces a much lower resistance connection than soldering. Imagine at least 20 connections (per pin) with an already low contact resistance per point now in parallel! Practically zero resistance!

[MusicalSeizureGuy]

I like watching this stuff, even if I don't understand most of it.

[aaronmurphy]

I needed some small wire for messing around prototype, radioshack had the wire and box says they sell the tool also. The gentleman there was surprised and had no clue about the tools mentioned.. lol. Thanks for sharing the process. Btw, kinda reminds me of thread applicator for tieing fly's for trout fishing, minus auto twist on feature.

[psyolent.]

good tip with the insulated wire wrap to start with so it doesnt break. thanks bill.

[cpcfreak]

We had manual wrapping tools that held a small spool of wire, and they would strip and wrap all in one action, they were so fast to daisy chain posts because no stripping. On the last post there was a button on the tool you held at the end of the last wrap which caused the wire to cut in about 1/2 a turn.

[cgdca]

Great video. Watching it I have rediscovered wire wrapping (an old fine technique). Good luck from Barcelona.