Largest wire dimension to fit into Duet's Molex KK crimp pins?



  • My Duet Wifi came with Würth Elektronik Molex KK compatible crimp pins. According to specification of these crimp pins (which is in line with the original Molex specs) largest wire dimension should be AWG22 or 0.34mm².

    Now you can say anything on paper and I guess they chose a dimension that will always fit in there no matter what manufacturer of the cable which all do things just a little different.

    What I'd like to know is personal experience of other users here. What was the largest wire dimension you successfully could crimp into these crimp pins?



  • Closely related I've had a frustrating experience with some old multi core leads that I re-purposed as stepper leads. The JST contacts were designed for 24-28AWG I think and my wire was 22.

    Rachet crimper and 22AWG is just about workable but leaves wires that are highly likely to fail just behind the crimp. I won't be over sizing again knowingly!



  • I've crimped the terminals onto 18 AWG stranded wire successfully BUT the insulation can be problematic. My cables were actually 16ga CCA (about 18 AWG) but the insulation wouldn't even fit inside the housing let alone the insulation crimp part of the terminal. I had to strip the wire further back and use short lengths of heat shrink to cover the bare conductor.



  • I've crimped 20 AWG with silicone insulation, with no problem.

    BUT... I DO NOT use the recommended ratcheting crimpers. Instead, I use a simpler "flat" crimper and I crimp in four separate operations, two on the "wire" fold-over wings, and two on the "insulation" fold-over wings.

    Realize that the expensive ratcheting crimpers are designed for "most number of crimps per hour"... and are NOT necessarily optimized for "produce the best crimps with different wire sizes and insulation". While very slow, you can actually get better results with other methods.



  • @danal said in Largest wire dimension to fit into Duet's Molex KK crimp pins?:

    While very slow, you can actually get better results with other methods.

    Oh I'm so glad that someone else has said that. My favourite tool for crimping is a pair of curved, needle nosed pliers - then sometimes I use a "proper" crimping tool to "round off" my square crimps. For whatever reason, I just can't get on with "proper" crimping tools and always end up with a bad job.



  • @danal I think we have the same crimping tool. Or nearly the same. IIRC you have Engineer PA-21 and I just bought a PA-20 last week.

    Do I get your method right that you do two crimping operations on each pair of wings by once crimping them towards their end that will go into the connector and once towards the end going to insulation? If not, how are you doing these two steps (per pair of wings) then?

    @deckingman If you do not like the ratcheting crimping tools either, did you have a look at Engineer PA-20/PA-21? They are awesome quality, lightweight and I loved them from the first crimping I did. 🙂



  • @wilriker said in Largest wire dimension to fit into Duet's Molex KK crimp pins?:

    @deckingman If you do not like the ratcheting crimping tools either, did you have a look at Engineer PA-20/PA-21? They are awesome quality, lightweight and I loved them from the first crimping I did. 🙂

    I've got something very similar, (as well as the racheting type). But I've become quite proficient with my curved, long nose pliers. Not that I do a lot of crimping though- none at all if I can possible avoid it. ☺

    Edit. Love designing and building machines - hate wiring the damned things.☺



  • @wilriker said in Largest wire dimension to fit into Duet's Molex KK crimp pins?:

    Do I get your method right that you do two crimping operations on each pair of wings by once crimping them towards their end that will go into the connector and once towards the end going to insulation? If not, how are you doing these two steps (per pair of wings) then?

    I do use a PA-20.

    I crimp the wings that will grip the bare wire once, fairly gently, in the 2.2 slot, and the same wings again, firmly, in the 1.9 slot. This seems to give the best results on the connectors included with the duet. The insulation wings may get 2.5/2.2 or 2.2/1.9, depending on the insulation. Four operations total.

    For "radio control" connectors, which are smaller, the final crimp of the wire wings occurs in the 1.6 slot.

    I understand what you are saying about the "thickness" of a PA20 vs. the "longways" dimension of the wings, and that it is easy to have a little "hanging out" of one side or the other of the crimper. However, if done carefully, the entire longways/thickness happens in each operation. I find that even with magnifying glasses, I can't get this right entirely by eye... a fingernail really sets the final depth alignment.


 

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