Attaching stranded wire to headers/pins

[Clare Sloggett]

Hi guys,

Some naive questions!

I have some stranded wires in a (miniDIN) cable that I've cut, and I
want to attach male headers so that I can use said wires conveniently
with breadboards and specifically, with an arduino. In fact for those
interested, what I am trying to do is use an arduino to control my
roomba, as described here: http://www.netfluvia.org/layer8/?p=127
Some of the software has improved since that project I think, so I
won't have all the same issues. But the basic connection using the
cut-in-half 8-pin miniDIN cable is the same. Basically the end of the
cable plugs into the roomba (which isn't really relevant to my
question) and the cut wires from the cable need to connect to my
circuitry. I have finally got my hands on the cable and can get
started!

That blog says he "soldered male header pins" to the cut and stripped
wires. After a bit of googling around, it seems to me that my two
options are to solder headers to the wires as he did, or to use crimp
pins. I can see crimp pins (and housings for them) at e.g.
http://littlebirdelectronics.com/products/male-crimp-pins-for-01-housings-100-pack
and I suppose these would work?
I have to say that crimping pins around stranded wire sounds a lot
easier than trying to solder it securely to something! But, I've never
used these. Is this really a good option? Have I missed some better
options?

Thanks for any help! I will be in on Saturday or Tuesday if it's
easier to talk about with the aid of the internet - I had all my new
components packed to come tonight, and then couldn't make it :(

Clare

[Stuart Young]

On 22 August 2012 00:52, Clare Sloggett <clares...@gmail.com> wrote:
> I have some stranded wires in a (miniDIN) cable that I've cut, and I
> want to attach male headers so that I can use said wires conveniently
> with breadboards and specifically, with an arduino. In fact for those
> interested, what I am trying to do is use an arduino to control my
> roomba, as described here: http://www.netfluvia.org/layer8/?p=127
> Some of the software has improved since that project I think, so I
> won't have all the same issues. But the basic connection using the
> cut-in-half 8-pin miniDIN cable is the same. Basically the end of the
> cable plugs into the roomba (which isn't really relevant to my
> question) and the cut wires from the cable need to connect to my
> circuitry. I have finally got my hands on the cable and can get
> started!

Yay!

> That blog says he "soldered male header pins" to the cut and stripped
> wires. After a bit of googling around, it seems to me that my two
> options are to solder headers to the wires as he did, or to use crimp
> pins. I can see crimp pins (and housings for them) at e.g.
> http://littlebirdelectronics.com/products/male-crimp-pins-for-01-housings-100-pack
> and I suppose these would work?
> I have to say that crimping pins around stranded wire sounds a lot
> easier than trying to solder it securely to something! But, I've never
> used these. Is this really a good option? Have I missed some better
> options?

The pins work quite well (as long as they're the right size to fit
into a breadboard), but it's best if you have a crimping tool that is
designed for those sort of connectors. It's the same tool used for
crimping the female headers which are used for 0.1" molex connectors
(flat as well as keyed styles) as well. FWIW: I own one of these tools
(those sort of connectors are all over my 3D printer) so I can bring
that in for you to crimp the connectors. I haven't found one for sale
lately at what I'd call the right price, otherwise I would have bought
one for CCHS (then I wouldn't have to keep bringing mine to CCHS on 3D
printer nights!).

FWIW: http://littlebirdelectronics.com/products/crimping-tool-for-01-housing-crimp-pins
is a nice tool, but probably more than I'd want to pay. You should be
able to pick a suitable tool up locally for cheaper than that. The
same also goes for the pins themselves. I personally prefer the
non-ratchet version of this tool (which is what I own), but everyone
has their own preferences.

You can do it with pliers, but it can be a bit annoying and the
connections end up being a bit sloppy.

Either way, tin the wires prior to crimping them.

Also: As these are pins, you can crimp the wire and then solder it
into the crimped part of the connector. This guarantees a connection
and will stop it falling apart if you're worried the crimp isn't
solid.

Lastly, once you've crimped the pins, I'd recommend covering the crimp
end with a small piece of heatshrink. This will remove strain from the
wire so it doesn't break right at the connector, and also makes it
nicer to push/pull for insertion/removal from your breadboard (stops
you accidentally stabbing yourself on any bits of metal that are part
of the crimp pin).

> Thanks for any help! I will be in on Saturday or Tuesday if it's
> easier to talk about with the aid of the internet - I had all my new
> components packed to come tonight, and then couldn't make it :(

Will be there Tuesday, but probably not Saturday.

--
Stuart Young (aka Cefiar)

[Michael Borthwick]

On 22/08/2012, at 12:52 AM, Clare Sloggett wrote:

> That blog says he "soldered male header pins" to the cut and stripped
> wires. After a bit of googling around, it seems to me that my two
> options are to solder headers to the wires as he did, or to use crimp
> pins.

Hi Clare,

I don't know anyone who wouldn't just solder the stranded wire to the
pins of the standard 2.54mm pitch male header. To make it neater and
more durable cover the joints with heatshrink tubing.

Classically you would 'tin' the two items being soldering (ie precoat
with a thin layer of solder) then bring the two tinned parts, the
soldering iron tip and a bit of extra solder (if only to help the
initial conduction of heat into the joint) together.

If find this requires four hands so I use a little jig comprising two
wooden clothes pegs screwed to a scrap of wood, or you could use
weights, electrical tape or get some way to hold the terminal and wire
together. It can be very fiddly otherwise.

Then run a fine bead of solder along the joint between the pin and the
wire.

If you are going to put some heatshrink on you will need to have the
leads longer than you might otherwise, because you need to slide the
heatshrink away from the joint far enough so that is doesn't shrink
prematurely while you're soldering. It is a PITA to remove when that
happens.

Here is a little video of how I would do it.

http://vimeo.com/47975087

Mike

[Clifford Heath]

I have a favourite way of making such connectors.

I usually start with the single-row header pins that Rockby sell, like these:
<http://rockby.com.au/catresults.cfm?imageField2.x=0&imageField2.y=0&stock_no=25582>

Place heat shrink over each wire, solder to the pin, shrink them all.
Here's the special bit: encase the whole back end in hot-melt glue.
While the glue is still hot, wet your fingers and smooth it back along
the cable. This forms an excellent strain relief. The resultant connectors
last long time and won't short out like individual pins would.

I've done similar things with pogo pins to make a 2-row pogo plug.
in this case I didn't use a header strip, but arranged the pogos in a
DIL header socket before joining them in place with hot-melt, which
forms the entire body of the plug.

Clifford Heath.

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[Luke Weston]

I don't think you need the fancy crimp pins, that's just an extra expense and wait for delivery that I think is completely unnecessary. Ordinary header pins are easily available anywhere, eg. Jaycar.

Strip the wire, twist it together, tin it, and trim off the stripped, tinned section so it's not too long. I do this trimming after tinning the wire, because the heat causes the insulation on the wire to melt slightly and pull back.

I would trim the wire so that the exposed, tinned section is only 2-3 mm, and the insulation on the wire goes right up to the end of the header pin, and the exposed bit completely overlaps the pin and is within the solder joint, basically. In other words, don't have a longer length of exposed wire sticking out, because it looks ugly and needs to be insulated.

Then apply solder to the header pin, put the wire onto the header pin and solder it all on, and once they're all soldered on, apply hot glue for strain relief.

As far as communicating and practising the actual technique is concerned, yes, I think it's much easier to watch you do it in person and help you do it than it is to try and communicate it in words in an email. Next time we're both at a meeting I'll help out in this regard.

Basically, the technique I would use is very similar to Mike's excellent little video, except I would not use heatshrink, I would run a bead of hot glue along the wires and the back of the header pins, essentially to provide mechanical coupling between the insulation on the wires and the header strip, so there is no tension on the solder joints during plugging/unplugging. It also provides insulation, although insulation isn't really needed because there is no exposed wire that is loose and free to move.

Cheers,
  Luke

[Clare Sloggett]

Wow, thanks for all the suggestions everyone! I haven't even had a
chance to think about this all week, but tonight have brought the
cable etc along.

So, I'll try some things out at the space tonight. I suspect I will
try out soldering first, because I should have some headers but would
still need to get pins. My soldering is not so great so I might need
to practice a bit. I don't suppose we have any "junk" stranded wire
around?

See you soon!

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[Andy Gelme]

hi Clare,

On 2012-08-28 16:50 , Clare Sloggett wrote:
> Wow, thanks for all the suggestions everyone!

With "n" hackers ... you'll get at least "n + 1" recommendations :)

> I don't suppose we have any "junk" stranded wire around ?

There is stuff laying around that you can practice on.

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