Author Topic: Crimping technique for Dupont connectors?  (Read 5668 times)

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Offline analogix

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Crimping technique for Dupont connectors?
« on: June 06, 2017, 03:22:08 pm »
I've recently bought a cheap SN-28B crimping tools so I can crimp my own "Dupont" connectors. It's for the occasional hobby use so I can't justify paying 10 times that much for such a tool. But the big question is how to use it! Not surprisingly it didn't come with any instructions and the "How to" videos on Youtube don't show the essential stuff like orientation and placement of the pin before crimping. I've so far cut numerous wires and squished pins because of my ignorance.

Are there any complete and detailed videos or websites explaining how to do this?

Offline edavid

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Re: Crimping technique for Dupont connectors?
« Reply #1 on: June 06, 2017, 03:35:36 pm »
How about this?

http://www.instructables.com/id/Dupont-Crimp-Tool-Tutorial/

It definitely takes practice to get it right.
 

Offline analogix

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Re: Crimping technique for Dupont connectors?
« Reply #2 on: June 06, 2017, 03:50:35 pm »
Perfect! Exactly the type of detailed instructions I was looking for.
Thanks  :)

Offline ElektroQuark

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Re: Crimping technique for Dupont connectors?
« Reply #3 on: June 06, 2017, 04:54:26 pm »
In Spanish, from my blog, with the same tool, HERE

Offline tooki

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Re: Crimping technique for Dupont connectors?
« Reply #4 on: June 06, 2017, 08:04:18 pm »
Despite the often crappy videography, this fairly long video is by far the best explanation I've found: 

https://youtu.be/W9w2IN3TqAg

That said -- and I happened to have just spent a ton of time last week working on this -- Dupont crimping is still a mess. Why? Because a) the Chinese crimp pliers (regardless of what kind) are not the correct tooling (Dupont pins are intended for a round surface bend on the strain relief, not the kind that squeezes into the insulation, as all the Chinese tools do.), and b) there isn't one "Dupont" standard, so the actual dimensions of the crimp pins varies by manufacturer, as do the tools. (And indeed, not all Dupont pins and housings are compatible, though I've had luck so far in this regard.) It is entirely possible that your intuition has you doing everything right, but resulting in bad crimps because the tools and parts are incompatible.

Also, the cheap chinese pins are rarely marketed specifically for specific wire gauges. (The name-brand ones exist in distinct crimp pins for thicker and thinner wire.)

I have an SN-28B as well (among others), and realized after much experimentation that it's categorically incompatible with the female pins I have -- the jaw width is too large, crushing the insulation crimp in the conductor crimp area. The male ones work OK, but even with them, it's at the outer limits of the tolerances. I have two different manufacturers each of both M and F, same applies, even if there are differences. If you use the instructables guide with my combination of female pins and tool, you completely crush the actual socket area.

As best I can tell -- short of switching to original Amphenol mini-PV series or Molex C-Grid, and respective  official tooling -- an SN-28B is probably the best for male duponts, and the SN-01BM (which apparently is identical to the SN-02BM) is best for the female ones. One vendor makes one called SN-2549 which combines an SN-28B with an SN-01BM.


Maybe you can do me a favor and measure the jaw thickness of your SN-28B?

If you want, I can do some demo crimps (successful and failed) and take pix for you tomorrow. Or show you on Skype or something if you prefer.
 
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Offline analogix

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Re: Crimping technique for Dupont connectors?
« Reply #5 on: June 11, 2017, 11:30:15 pm »
Had I know it was this complicated I would just have kept ordering pre-made wires with connectors already on them from eBay.
It's just that I needed some custom lengths and I thought this would be easy  :P
I'll take a closer look at the links posted here so I can figure out the details as I'm obviously doing something very wrong (but none of this is obvious IMHO).

I'll see if I can figure it out after practicing on some more wires first, before I take you up on your kind offer.
As for measuring the jaw thickness -where exactly do you want me to measure?

I looked up the SN-2549 on eBay and with all sellers of those being in the United States they're asking around the same cost as the actual tool for shipping. For my hobby use it's just not worth it with all the import duties, taxes and hassle on top of that. If I was doing this professionally it would be another issue entirely.
According to many videos it appears many people are having success with those SN-28B crimp tools, but again they rarely show the essential details which a newbie like me to this would need to understand in order to get it right.
« Last Edit: June 11, 2017, 11:32:16 pm by analogix »
 

Offline tooki

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Re: Crimping technique for Dupont connectors?
« Reply #6 on: June 12, 2017, 10:23:14 am »
I looked up the SN-2549 on eBay and with all sellers of those being in the United States they're asking around the same cost as the actual tool for shipping.
I'll respond to the rest of your reply in a bit. Meanwhile, here's a direct-from-china source: https://www.aliexpress.com/item/Free-shipping-Best-Quality-Reballing-BGA-Station-with-Handle-for-90mm-x-90mm-Stencils-Direct-heat/1268474971.html

(Ignore the fact that the URL was clearly reused from an unrelated item.)
 

Offline jeroen79

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Re: Crimping technique for Dupont connectors?
« Reply #7 on: June 12, 2017, 12:58:41 pm »
An important part is the thickness of the crimptool.
If it is thicker that the wire crimp part of the connector it will bite either into the mating part of the connector (which it absolutely should not!) or into the insulation crimp.
The latter is also unwanted as the insulation crimp will be larger in diameter due to the insulation, that would result in a lower quality wire crimp.
Some times it may 'just' fit but still bend the connector.

Some crimptools have two dies in one so that both the wire crimp and the insulation crimp are done in one go.
The connector should be positioned to that the wire crimp and the insulation crimp fir neatly into their part of the die with the mating part well clear of the die.
The point about the thickness applies here too, especially for the wire crimp part.

You can see that one half of the die is wider, the is for the insulation crimp.
The narrower part is for the wire crimp.
The wire would be on this side, the mating part on the other side.

You don't want to punch, touch, bend or push the mating part in any way!
It should stick well out of the tool.

Another point is the thickness of the wire and the die chosen.
If you try to crimp in a die that is too big for the wire the crimp will end up loose or too flattened instead of neatly wrapped around/into the wire.
 


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