Heatable Crimpless Connectors

We are thinking about using the crimpless connectors that you heat to connect the wires. Does anyone know if these are legal and if they are actually any good?

I played with those in an automotive application. I had trouble getting the solder to adequately flow into the wire and in one case (signal lights on my 1972 truck), resulted in a high-resistance connection. I switched back to heat-shrink crimpable butt connectors. Maybe you’d have better luck if you dip the wire in flux first but these things would probably not be my first choice.

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We’ve used them for years, primarily for making PWM Y-cables. They’re legal (at least I hope so since I also inspect).
They work well for smaller wire sizes, say 22 or 24 AWG. It’s hard to get enough heat into the larger ones to get that miracle metal in the center to flow.

Get a proper ratcheting crimping tool and learn to use it.

I have never seen such connectors used in professional applications.

It will be difficult to get sufficient heat where you need it for long enough to melt the solder AND keep it away from where you don’t want it. If you use a heat gun, you might melt the insulation off the wires on both sides. Torches can focus the heat but will not be allowed at competitions.

Solder joints should also be inspected to ensure the solder flowed properly. It is not possible to inspect the solder joints with those connectors and you might end up with a temporary connection that breaks apart with a slight amount of stress.

Legal, yup.

Probably ill-advised, also yup.

We got them for pit repairs but have never used them because Wago levernuts are awesome.

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We use them and like them, just make sure you have a good heat gun. Also it wouldn’t hurt to watch a video or two on how to properly use them.

Also unlike Philso, in the wire harness shops I have worked at these connectors (plus ones with grounding wires) were pretty common sight.

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Thank you everyone for your feedback! I had never seen them before until this year, so I was curious.

Perhaps this could work reliably and consistently in a mass manufacturing environment with a well thought out manufacturing process, well trained workers and QC monitoring it all.

For FRC applications, I still feel the ratcheting crimpers will produce reliable results for more people more easily.


It’s weird the terminology used but since I’ve been in automotive wiring for 30+ years a “butt splice” is a splice where all the wires exit from the same direction.

I would call this a sealed one to one splice.

A local specialty vehicle manufacturer near our team does this.

We sell 2 sizes here at AndyMark, and I have used them in a few applications without failures. As long as you have a sufficient heat gun, and are careful not to leave it in one location so long that the solder part doesn’t leak out through a melt in the heat shrink, these have been great.

This is the one we use in our shop here. https://www.wagnerspraytech.com/products/heat-guns/furno-500/

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I’ve never seen the term used that way. I’ve always seen butt splices are where one wire is butted against the next.

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