How to connect tiny signal wires into screw terminal blocks?

[GigaNerdTheReckoning]

Hello,

I want to buy a terminal shield for a Nano. That is, every pin on the Nano is connected to a separate terminal block.

here's the shield;

1.19AU $ 16% OFF|Standard Terminal Adapter Board For Arduino Nano 3.0 V3.0...

I want to connect rainbow ribbon cable (I think they are usually around 26-28 ga and are the one's used for dupont connectors) into these terminal blocks.

The opposite end of these wires will be female dupont connectors, which can connect to peripherals, e.g. sd card module.

A higher gauge will be needed for the power supply into the Arduino.

The problem is that these 26-28ga signal wires are so thin, that they don't clamp very well into the terminal blocks. the strands will also degrade over repeated insertion and removal, are prone to fraying and are just not very pleasant to use.

I use wire ferrules for larger gauge wire to solve this problem, which work great, but my ferrule crimper cannot work with wires thinner than 24 gauge.

Any ideas of how I can get a better connection with these small signal wires?

Thanks!

[DrDiettrich]

@GigaNerdTheReckoning

I want to connect rainbow ribbon cable

Professional connectors exist for ribbon cables.

Eventually it helps to fold a thin wire and apply a fat solder lump on it. Most probably it will break at that (any such) transition, sooner or later.

[steve1001]

You can get terminal blocks that have a steel strip under the terminal screw (sorry I cannot recall the correct term). The terminal screw bears down on the steel strip, and the steel strip clamps the small thin wires. This avoids the screw mushing up the wires, and avoids the needs to solder them. Saying that I mostly tin my wires because they insert better. I bought a bucket load of these terminal blocks cheaply from Asia, and they work well on 'dupont size' wires.
Those 'choc block' things are a thing of the past.

[LarryD]

Don’t buy that screw terminal PCB for use with 28/30AWG wire.

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Suggest you get a board that uses headers @2.54mm .

Use a Dupont plug on these headers.

[cherk]

why not use male/female Dupont wires and the male end into the screw(ed) terminal block ?

[JohnRob]

I would look into using 2.54mm male headers with insulating displacement connectors for the wire end(s). You don't need a special crimper, a small bench vice will work.

[GigaNerdTheReckoning]

@steve1001

terminal blocks that have a steel strip under the terminal screw

That's the type I'm using. They definitely clamp in there tight, but still not very pleasant to use when prototyping.

@steve1001

(sorry I cannot recall the correct term)

I don't blame you...It took me forever to find out what they were called . The "wire termination" filter in this link seems to show the names; https://www.digikey.com.au/en/products/filter/terminal-blocks-wire-to-board/371?s=N4IgrCBcoA5QjAGhDOl4AYMF9tA

[GigaNerdTheReckoning]

Simple problems have simple solutions...A male header pin works great for one of those small terminal blocks (3.5mm pitch), with a rounded bottom, like this one Terminal Block - 2-pin 3.5mm - pack of 5! : ID 724 : $2.95 : Adafruit Industries, Unique & fun DIY electronics and kits. It doesn't even bend the pin too badly. thanks!

[GigaNerdTheReckoning]

@JohnRob

I would look into using 2.54mm male headers with insulating displacement connectors

Interesting!

@JohnRob

You don't need a special crimper

Good! anything involving a "special crimper" tool (except for bootlace ferrule crimpers) has been extremely hit and miss for me.

[GigaNerdTheReckoning]

Found my solution!

Crimping Small Wires - Digital Yacht News

Update: check here for a more optimized method; Share tips you have come across - #1019 by GigaNerdTheReckoning

I had a few "blade connectors" which I never ended up using. They were meant for thicker gauge wire, but as you can see, they also have a way of working with smaller wires

You simply strip around 40mm of the thin gauge wire and wrap the wire backwards over the insulation. Then you get some good quality crimping pliers (I used Irwin) and crimp the connecter over the wire and the insulation. As you can see, I had to crimp twice, to get the cylinder to overlap.

I've never had very consistent results with crimpers, but this feels like a very strong and reliable connection!

And because there's no solder, it might be suitable for automotive and marine applications.

I also tried soldering the wire to the connector...Adding in heat shrink tubing gives it some strain relief. Definitely prefer the crimping though;

As another commenter pointed out, you can also just insert male jumper wires into the terminal block.

However, the flat blade connectors can clamp a lot easier and tighter into the particular terminal blocks I'm showing. I'm using a terminal block that clamps onto a flat surface, specifically this version;

The male dupont connector bends when I place it in that specific terminal block, but the blade connector does not bend.

I believe that the male dupont connector is better suited for a terminal block with a round bottom (it doesn't bend as much), like this one;

OSTTC022162 | Digi-Key Electronics

the blade connector also connects well into these push terminal blocks...

also made a ring connector using the same method...

[raschemmel]

You can also use small ferrules

if you have a ferrule crimper

[GigaNerdTheReckoning]

Thanks. I've since found that there exists crimpers and ferrules that can go all the way to 28ga, so this sounds like the best solution.

I've also experimented with wrapping the wire backwards over the insulation and then crimping it with a larger gauge ferrule (as my ferrule crimper only goes to 24 awg). This seems to clamp perfectly well into the terminal, however this method isn't able to produce the flat and even square shape that a normal ferrule crimp (or blade connector) can provide.

the advantage of having a flat square shape (which ferrules and blade connectors provide) is that the terminal-block clamp has a larger surface area to grip on to. Ferrules and blade connectors are also corrugated, which I assume would provide a stronger grip.

Regardless, all the methods I've mentioned seem to work perfectly fine, so there's lots of options.

[6v6gt]

@GigaNerdTheReckoning

. . . The opposite end of these wires will be female dupont connectors, which can connect to peripherals, e.g. sd card module.

I would have then have considered a set of ready made male to female dupont connectors. Use the male end in the screw connector.
You could also use female to female and, on one end, remove the black housing and maybe partially cut back the exposed metal connector to have something usable in thr screw connector.

[LarryD]

Yes, a Dupont female flattened would do nicely.

[LarryD]

Hey, how about making a post in "Share tips you have come across" on this idea ?
I added it to that post

Here you see the front and back of a Dupont male connector with the tip removed and then flattened:

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[GigaNerdTheReckoning]

yeah both female and male work great. The naked female's (LOL ...meaning females with the dupont shell removed) also have plenty of clearance to stack on top of eachother, so you can easily place 2, possibly 3 wires in a single pole of the terminal block.

[LarryD]

@GigaNerdTheReckoning

The naked female's

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And you can partially dress them with a bit of heat shrink if desired.

Different colours of heat shrink maybe: BK, BN, R, O, Y, GN, BE, V, SL, and W.

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Yellow goes into terminal 4 and maybe Brown with Yellow goes into terminal 14

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This has been added to Share tips you have come across :

Share tips you have come across

28 AWG DIY ferrules for screw terminals In another post, a user asked how to terminate 28 AWG wire in a screw type terminal strip. @6v6gt suggested to use a Dupont crimp connector to act as homemade ferrule. Below shows how this process can be accomplished. Add heat shrink to act as a strain relief. The colour of this heat shrink can identify the terminal number to use: Yellow would be terminal #4 Brown and Yellow would be #14, etc. [A] [B] [C] [D] [E] [F]