Why You Should Try Ferrules

I don’t know how many people actually know about them. I learned only when I was invited to help at a industrial controls/robotics outfit.

You know those little screw-type terminals you might find on a home theater receiver, a car audio amplifier, sprinkler control, thermostat or any other of the myriad things we use that connect directly via wire?

One non-secret nobody may have ever told you: those screw terminals require a minimum gauge of solid core, ideally soft (pure copper) wire. If you’ve ever worked around car or home audio equipment you’ll probably know that stranded wire is kind of expected, if not very common. Especially in automotive applications, flexing and constant heating-cooling cycles will inevitably find a way to disconnect solid wire. Worse, it may be intermittent, creating the kind of electrical gremlin that totals cars.

Really, unless you’ve got butt connectors and a use-specific crimping tool and/or screw/wingnuts, there’s really no good way to connect to a stranded wire without soldering. I remember countless times as a teen I just shoved a twisted copper wire, maybe folded back on itself if I was thinking extra hard that day, and the strands squish around the screw inside the terminal box and break and the wire would simply fall out.

It was only a couple years ago now, right before I was given the offer and took the job I’m currently working as a full time “SWE”, I was selling gear on FB marketplace for money to eat. I had to sell my Rigol 1054z 4-channel 100mhz oscilloscope. I got a bite from a guy in the biggest nearby city, and he asked me if I knew what the device I was selling was. I plugged it in and connected a probe dangling to prove that I did know it was an oscilloscope and I could show that it was picking up the background 60hz AC in the house.

Little did I know, that was a test. This guy wasn’t really looking for electronic equipment, everything he was buying was second-hand Rockwell, Allen Bradley or Fanuc equipment. He really just needed a hired hand and so people selling related equipment on Facebook was an expeditious way to find that type of person. We met at a nice little Mexican chain in town, ate, and I sold him the oscilloscope (he paid me more than I asked after learning my position in life, bless the man, and he also paid for lunch) and we spent a few hours building rapport around a shared interest in all things electronics, the out-of-place feeling you get as this kind of person living in our neck woods, and life generally. I really, really enjoyed meeting this guy.

Before I took my current job I spent a handful of days and evenings with him in his shop. It started out simple, assembling a few new shelves that were going to be used for development of the next automation “cell” or stage of an assembly line operated by a huge robotic arm. Then it was sorting though some code to get a computer running, sorting through some bins with useful and non-useful wires, then finally, the last thing I did was disassemble some DIN-mount control hardware that had been hastily cut out of a box with dangling wires still in the terminals. I realized while disassembling them that not a single wire would budge from it’s terminal box without the screw in the terminal being backed off almost entirely. The difference between this and all the other screw terminals I had used? It was stranded wire installed with square-crimped ferrules, every last one.

When you get that kind of experience, it can take you one of two ways: you can file away that knowledge, at best bringing it up in conversation about best practice, or whatever, or you can use it. I was still single at the time and there wasn’t much better to do with my time outside of work so I spent hundreds of dollars and dozens of hours on my little hobbyist electronics projects, one at a time. None of them are ever very interesting, I do them for myself and I choose not to take things to a production-ready state because of something called the “arrival fallacy” — you think you will be happy when you get there, but the fun was actually the journey and friends you make along the way. But I did waste the $25 or whatever it took to get a kit of ferrules and a hexagonal crimping tool, because that’s cooler than squares, right?

I learned later that squares are potentially stronger-holding, but I like to think the way a hexagonal crimp crushes outward can’t hurt too much.

Well, I lost that tool when I moved. I don’t have a centralized electronics lab or workbench, instead I just plug in my soldering iron wherever and hope I don’t burn the carpet. But this, when I lost these ferrules and these tools, it just stuck in my mind. Almost every little electronics module that I use to power things, from 12V 1A buck converters all the way up to 48V 5A boost converters, they all use screw terminals. I even have my own screw terminals for adding to a board when broken or connecting stranded wire to a breadboard.

I had to buy another. It was months and months after I had realized it went missing and I wanted to use it for so many things. I finally did, and a few weeks later I found the original because that new crimping tool empowered me to get back to my hobby projects and motivated me to look through more boxes.

I will never hesitate again to buy a ferrule crimping tool or the ferrules, no matter how upset I am at losing the existing ones. They are pure joy, and they make all kinds of connections safer, more solid, and more idiot-proof. Trust me, I need that last one.

Thanks for reading!