How to make a REALLY vibration-resistant wire crimp

[626Pilot]

There have been times when I've had crimps near the effector platform start to get flaky a week or two after I made them. Sometimes the rated AWG range for a pin crimp (say, 16-22) will give you the idea that your wire is of an acceptable gauge, but it doesn't always work out. You can try folding the wire over to make it thicker, but there's a way to just skip all that and make it work, reliably, with no wiggle room, EVERY time!

After you do the crimp, place a hot soldering iron on the crimp and feed in a little bit of solder so that it flows into the crimp and around the wire. This creates a solid connection that won't allow any movement whatsoever within the crimp, and will increase the contact between the wire and the crimp. Don't put in so much that it could interfere with anything, especially if you're crimping a female pin connector, but it isn't too difficult. This will work OK with solid wire and better with stranded wire.

I used this technique with the metal ferrules that came with both of my E3D hot ends (where you connect the thermistor to the insulated wires) and also for the 4- and 6-pin connectors on my custom hot end wiring harness. Since I did this I have had NO problems, and I never expect to either!

[Captain Starfish]

It feels solid at first, and I do it too for the lightweight connectors (JST or molex style).

But for the bigger stuff, go look up "cold flow" of solder. All kinds of electrical standards prohibit the use of solder in crimped or screw locked terminals because it feels rock solid to start with but, over time, the solder will flow away from pressure points allowing wiggle room which can eventually give you an intermittent connection, popped wire, or - worst of all on high current or sensor leads coz it's so hard to find - a point which still conducts but with a much higher impedance.

[626Pilot]

Thanks for letting me know about that. I checked all my connectors for evidence of the solder "leaking" but there was none, even though they are vertical and should encourage that. The amount of solder used is not too much. I'll probably check it again in a few months, or if it starts acting weird, but I'll take that over the crimps getting flaky every few weeks. My connectors are sold by TE Connectivity AKA Amphenol. They're similar to JST or small Molex.

[Captain Starfish]

Just tuck the info in the back of your mind in case things start getting weird. I agree though, big improvement on the PITA of things coming adrift every week or so.

[626Pilot]

BTW, regarding cold flow, I did solder the ends of the wires that connect to the heated bed port on the RAMBo once. It eventually caused arcing and I had to replace the Molex connector. I think it's a particularly bad idea to solder a stranded wire that goes into a screw terminal of any kind because it will directly interfere with the clamping mechanism. It works in crimps because you flow the solder after the crimp is already squeezed.