SO3 Molex connectors for steppers

Wanted to share my research I just did for sourcing the 4 pin Molex KK connectors used on the SO3 steppers and controller board. I am upgrading the cables to shielded 22 awg so needed these. I found some incomplete info here and there, so hope this helps someone.

Crimp Terminal Housing (female):
Crimp Terminal (pins):
Header (male):


I’m going to try the GX16-5 Aviation connectors when I do mine.

Thanks for the information!

What crimper are you using for the Pins?

The Molex crimper is very expensive.

Havent tried them yet on these Molex pins, but I usually use my $35 Pololu crimpers for pins like these. Hopefully they work.


I’m planning to use a pair of pliers and then solder the wire to the pin.

I am planning on doing similar.
I was at the back of the machine today and looked at one of the connectors, wondering what to do with that extra foot or so of wire that comes from the stepper motor itself and looked (again) at the difference in wire gauge from the stepper motor and from the wire harness.

I notice that you chose to stick with the 22 awg, so, my question, do you feel that 22 awg is adequate?

Yeah I have been back and forth on the need for 18 awg. Since I posted this I have decided to move my controller into the electronics area of my enclosure (instead of rail mounting it). The will significantly increase the length, so will likely be doing 18 awg anyway.

Here’s a quote from eevblog about soldering crimp connections:

“The main problem with soldering after crimping is wicking. Most crimping is of multi-strand wires. Solder is drawn between the strands for a considerable distance, just as wax is drawn up a candle wick. Where that solder ends you have a point where often just a few wiggles of the wire will cause a fracture”

Be careful with the solder wicking up the wire and creating a fragile joint.

These are much cheaper than the molex crimper:

I like them a lot better than the ratcheting all in one style. With these it is a 2 step process first you crimp the wire and then the insulation. Its slower but I can check with a tug to see that the crimp is good before crimping the insulation.


@npross Wanted to thank you for the recommendation on those crimpers. Love the simplicity over the dual crimp ones that try to crimp both the conductor and insulator at the same time. The quality of my crimps have gone up significantly.

Look nice… but I have yet to find a set that wasn’t junk. Sometimes you get painted plastic, sometimes you get chinesium-metal, the pins aren’t separable, and the plating on them is super sketchy. They look ok on the surface, but really, they’re junk.

These work really well, really secure. This is a really high quality wire-wire connector.

Housings here, easy links from there to pins:|3972

Oh, and great crimpers:

@Croy9000 you’re welcome.

I cant afford to get the manufactures crimpers for every type of crimp. I read a blog post showing in detail the difference between the perfect crimps from the correct tool vs what we get from cheaper crimpers but I figure I’m not selling my crimps so as long as they work for me…
The engineer crimpers arent perfect but, like you’ve experienced, my crimps also are a lot better than I was getting with my cheap 1 step chinese crimpers.

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