(Electronic) Wire-Wrapping

Introduction

I’m working on my on-again, off-again digital clock project, and one thing I learned before I broke off before is that the number and density of connections made soldering very impractical. So wire-wrapping it was. Some basic points:

  1. Wire-wrapping is spendy. Just getting a batch of sockets, a spool of wire, and an entry-level tool cost me around $100.
  2. Because of that, I can’t consider it worthwhile for less-ambitious (read: less complex) projects.
  3. You’re on your own, basically. There’s no instructions with the tool I ordered. I presume that’s typical for most tools.
  4. There’s an incredible variety of tools and wires out there.

So, with all that, here’s what I’ve learned so far.

Get a Less-Expensive Tool

Unless you’re really going to get into wire-wrapping, don’t get one of those gun tools. The base price is spendy enough, and they’re even more spendy than that! The gun tools (both electric and hand-powered) require both a bit and a collar, and both of those items are costly as well. Expect to spend $200 to $300 or more just to get a tool capable of making connections. Ouch!

Instead, opt for a “screwdriver” type tool. I’d recommend getting one made by a well-known name brand, because you are going to be making hundreds of connections on the typical project, given the size and complexity needed to make wire-wrapping make sense.

Use 30 Gauge Wire

Specifically, 30-gauge, Kynar-insulated, silver-plated wire. It’s basically the standard. (Just to make it interesting, they sometimes call Kynar by other names: PVDF, polyvinylidene fluoride, or polyvinylidene difluoride.)

Get the Right Tool

The tool you need is governed by both the wire gauge and the style of wrapping you’ll do. You already know the gauge; the wrapping style I’d recommend is the “modified” style that involves wrapping about a turn of insulated wire around the terminal posts before the bare wire starts. This provides a degree of strain relief, which minimizes the chance of things breaking while you wire your project.

Taken together, the right tool is the Jonard WSU-30M. It’s not much larger than a small screwdriver and costs over $30. Cheaper than the guns by far, but still, ouch! It’s a name-brand tool, and it’s well-known enough that there’s (incomplete, but still better than no) instructions for using it on the web.

An added plus is that the WSU-30M can remove connections as well as make them, so you don’t have to order a separate removing tool. The latter is a must, as Murphy’s Law says you will sooner or later make a wrong connection.

How to Use the Tool

There’s some instructions here. Alas, they’re missing one of the most important things: how much wire to use to account for wrapping and slack between two terminals. After some frustration, I arrived at the distance plus 7 cm (sorry, I’m not going to convert that to inches; I prefer working in metric because the math is easier).

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