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Basic question about connectors

Discussion in 'General Electronics Chat' started by MrDEB, Aug 6, 2018.

  1. MrDEB

    MrDEB Well-Known Member

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    I have a hub motor w/ 8 wires that need a connector (male and female)
    Wires are 22g -30g
    Looking for a durable, preferably water proof but tape will work just as well.
    Any favorite connectors?
    I had to cut the wire to install a disc brake rotor so it needs to be reconnected. This will actually be a better setup as one needs to remove the wheel to repair a flat tire or?
     
  2. AnalogKid

    AnalogKid Well-Known Member

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    There are tons of industrial strength connectors (rugged, waterproof, etc.) but most of them use crimp pins. If solder is more your speed, consider the ubiquitous 9-pin D-sub that is used for serial ports. Solder contacts, optional strain-relief backshell, splashproof as is, low cost, rated for 1 A per pin ...

    ak
     
  3. MrDEB

    MrDEB Well-Known Member

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  4. dave miyares

    Dave New Member

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  5. JonSea

    JonSea Well-Known Member

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    I think your guess of wire sizes is way off. 30 gage is wire-wrap wire.
     
  6. AnalogKid

    AnalogKid Well-Known Member

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    Agree. Crimping 30 ga wire into a standard .062" contact will be difficult. A small burr on the contact can shear the wire.

    ak
     
  7. MrDEB

    MrDEB Well-Known Member

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    I agree but work with what is available. There are two different gauge wires among the 8.
    My plan is to solder the clips then insert into holders.
    Should work.
     
  8. dave miyares

    Dave New Member

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  9. JonSea

    JonSea Well-Known Member

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    Solddring those pins is usually a bad idea - if you get solder in the clip part of the pin, it won't seat properly or stay in.
     
  10. gophert

    gophert Active Member

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    Bad ideas lead to failures that teach great lessons.
     
  11. JonSea

    JonSea Well-Known Member

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    Some people have tremendous immunity to learning from mistakes, or applying lessons learned to a larger scope.
     
  12. JonSea

    JonSea Well-Known Member

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    There's no need to make the same mistakes as others, or to make the same mistake over and over. There are plenty of new mistakes waiting to be made.
     
    Last edited: Aug 7, 2018
  13. gophert

    gophert Active Member

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    I disagree. Your line of thought pushes the idea that hands-on laboratory experiences are not necessary in education - "why give a student a chance to fail when they can just read the procedure and know what they should learn". There are plenty of reasons to make the same mistake as someone else while a student -or in need of a lesson. If one's only experience with failure is vicarious, then the joy of learning is less intense and the lessons of failure are less deeply engrained.
     
  14. JonSea

    JonSea Well-Known Member

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    You're welcome to disagree, and I am certain you will disagree with whatever I say anyway. It seems to give you great pleasure.

    Certainly, hands-off experience is important to learning. But it's also an excellent skill to learn from the mistakes of others.
     
  15. AnalogKid

    AnalogKid Well-Known Member

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    Yes, there is.

    ak
     
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  16. ChrisP58

    ChrisP58 Well-Known Member

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    One thing to be aware of. Unless you bend over the ears of the pins like would normally be done in the crimping process, the pins wont fit into the connector body.

    [​IMG]
     
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  17. MrDEB

    MrDEB Well-Known Member

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    I plan to crimp then solder.
    I measured the wire yesterday w/ sheathing still on.
    One measures .028 and the bigger one measures .071
    Looks like 12g and 22g wire?
     
  18. JonSea

    JonSea Well-Known Member

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    Soldering of crimped pins is not advised. As long as the pin is properly sized for the wire and a good mechanical connection is made, don't also solder it.

    If you solder a crimped pin, some of the solder will flow up the wire, leading to a stress point where the solder stops. Flexing will cause the wire to break at that point. When the pin is only crimped, the strands of the wire csn flex and move independently - there is less stress concentration.

    Before gophert can ridicule my comments, here's a great discussion on the topic at EEVBlog.
     
    Last edited: Aug 9, 2018 at 10:02 AM
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  19. shortbus=

    shortbus= Well-Known Member

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    But, when still working , GM Delphi Packard, they would dip solder the stripped wire, especially small gauges. The dip solder did not penetrate into the complete wire just the outside strands, to keep them together as the wires went went down the assembly line into the terminal press. But they weren't soldered after terminating.
     
  20. tomizett

    tomizett Active Member

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    I've soldered similar connector pins without problems in the past (generally the smaller Molex types, kk series, I think).
    I'll generally tin the wire, crimp the short set of ears (closest to the contact end) over it with pliers, then solder. When the joint is cool, I then fold over the longer ears on the insulation to provide mechanical support. ChrisP makes a good point that, if you don't do this, it won't fit into the housing. The trick is to work fast, so the solder has no time to wick down the pin and stop it mating (even then, they do go wrong for me sometimes).
    JonSea in #16 makes a good point, and one that might not be obvious straight away. In my applications, inside equipment, it's not a problem - on a vehicle it may be more significant.
    I'm sure we all agree that propper crimping makes the best joint (better than soldering I'm lead to believe), but it's my feeling that soldering will give a better joint than crimping without the correct tool.
     
    • Agree Agree x 2
  21. dknguyen

    dknguyen Well-Known Member

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    I don't know how you don't go crazy doing that for something as common as the Molex KK series. lol. Wherever there's one to do, there's usually several dozen more. So much time wasted instead of just spending $30 on a crimper
     
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  22. rjenkinsgb

    rjenkinsgb Active Member

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    I have to back the "solder it" side.
    (Carefully, of course).

    A valid electrical crimp connection needs the wire and connector at the crimp point put under sufficient pressure to cause them to extrude slightly, causing cold welds and driving out all traces of air at those weld points. That's the basis of a "gas tight" connection - it can never tarnish at the connection points.

    Connectors like the small molex ones do not actually form a long-term reliable connection when crimped with a cheap tool.
    Most don't even form a real crimped connection, they just fold the tags. I've lost count of the number of pieces of commercial gear I've seen with connectors like molex kk style (thin fold-over tags) causing problems after a few years, once they start to oxidize due to insufficient crimp force.


    Any so-called crimp tool like this (non-compound pliers style) is a joke and waste of space, other than as a convenience for neatly folding the tags:
    http://www.precisehandtools.com/image/cache/data/EBAY_THUMB_small-800x800.jpg

    For a mostly-reliable connection with a molex style, you need the exact correct tool for the individual pin form - and those tools are expensive!
    https://www.waytekwire.com/item/595/Molex-63811-6000-MX150-Ratchet-Crimping-Tool-/


    This style are OK for standard red/blue/yellow coded crimps, as long as the wire size matches so the actual connection point is full of copper before crimping.
    http://pelindustrialsupply.com/wp-content/uploads/2016/03/crimping-tool.jpg
    (Again, the non-compound plier type tool often sold for these is just plain lethal - the terminals are often barely attached, never mind actually crimped..)

    And these are excellent for bigger stuff:
    https://uk.rs-online.com/web/p/crimp-tools/0445611/

    Even the hideously expensive industrial tools with exact fitted dies are no use if the wire size is not a correct match or the crimp is a clone that has thinner walls than the type the die was made for.
     

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