Author Topic: Connector for slightly bigger wire than will fit in JST SM  (Read 662 times)

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Offline davethomaspilotTopic starter

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Connector for slightly bigger wire than will fit in JST SM
« on: April 13, 2023, 09:17:58 pm »
The insulation on the wires is too big to fit in the JST SM contacts. 

Wire size (insulation) is 2 mm diameter.  It just won't fit.

First, does it really matter?  Crimps seem really strong--I can't pull the wire out of the crimp.

If it does, can some one recommend a slightly larger connector that's easy to crimp?  1.5 amps, low voltage rating.

Just two wires--application is for adding a crimp connector to the 12V side of a 12V to 5V DC/DC. 



 

Online thm_w

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Re: Connector for slightly bigger wire than will fit in JST SM
« Reply #1 on: April 13, 2023, 09:55:47 pm »
Does it matter for hobby use? no.

What AWG wire, you don't have anything thinner? The SM contact is rated 28-22 AWG.

https://www.jst.com/wp-content/uploads/2021/03/eSM.pdf
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Offline davethomaspilotTopic starter

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Re: Connector for slightly bigger wire than will fit in JST SM
« Reply #2 on: April 13, 2023, 10:11:33 pm »
Don't know wire gauge, except it's about .95 mm diameter.  19 or 20 AWG.  Can't change it--the DC/DC convertors I have on hand have the wires.

Not quite hobby--I'm making 10 assemblies that cost around $1K each.  They will be used only once or twice a year, but will be expected to last at least 10 years.

The crimp on the wire is really good--it's just that the insulation won't fit under the outer crimp.  Thinking about it, I wouldn't think the extra mechanical strength provided by getting the insulation under the crimp would be significant compared to the actual wire.  But, I know a "good" crimp requires the insulation to be in the crimp.

Found these on Amazon and will give them a try:

https://www.amazon.com/Molex-Micro-Fit-Circuits-receptacle-Terminal/dp/B078PZY6SM/ref=sr_1_2?qid=1681422924&refinements=p_n_feature_four_browse-bin%3A18945778011&s=industrial&sr=1-2

Thanks!



 

Offline davethomaspilotTopic starter

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Re: Connector for slightly bigger wire than will fit in JST SM
« Reply #3 on: April 13, 2023, 10:14:56 pm »
The maximum insulation thickness for the ones in that link is 1.8 mm--same as the SM that I've used.

Outside diameter is 2 mm.

I actually shaved some insulation off the wires and got a pair of wires to fit.  But, that's too much hassle and I still don't think it adds significant mechanical strength compared to something like 20 AWG wire.  But, opinions welcome!

 

Online thm_w

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Re: Connector for slightly bigger wire than will fit in JST SM
« Reply #4 on: April 13, 2023, 10:25:10 pm »
If this is for a high end product, then yeah just get an appropriate connector that is rated for ~19 AWG wire.

Mini fit jr. can be 18-24 AWG
Micro fit contacts you linked are 20-24 AWG so might work.

Probably this https://www.molex.com/pdm_docs/ps/PS-44300-001.pdf
Spec states max outside insulation diameter 1.85mm
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Offline davethomaspilotTopic starter

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Re: Connector for slightly bigger wire than will fit in JST SM
« Reply #5 on: April 13, 2023, 11:03:47 pm »
Quote
Spec states max outside insulation diameter 1.85mm

Two small--measures 2.0 mm.

SH (what I have) is spec'ed at 1.8.  Definitely too small.

Wire fits fine though.
 

Online wraper

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Re: Connector for slightly bigger wire than will fit in JST SM
« Reply #6 on: April 13, 2023, 11:19:22 pm »
If it's vibration free environment, wires won't be bent in use and it's just a one-off, strip more insulation and crimp stripped part only.
 
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