Small wires - alternative to Butt connector

[dennismenace111]

Originally Posted by wingless

These 3M Scotchlok UR2 and UY2 connectors are good for small wires.

The connector is filled w/ a sealant for moisture resistance.

They are rated for 26-19 AWG solid conductor.

I love these things, but they are built for voice comm wiring....solid conductor not stranded conductor. Do they still work on stranded or do you have to tin the strands together with solder first?

[a64pilot]

The way the work is to push down a sort of knife of you will into the wore, which obviously may well cut some of the strands.
But if you have ever used these things on cars etc, they do exactly the same thing, and yet seem to work fine.

[a64pilot]

Originally Posted by dennismenace111

I love these things, but they are built for voice comm wiring....solid conductor not stranded conductor. Do they still work on stranded or do you have to tin the strands together with solder first?

I believe you don’t even strip the wire, just stick them in and squeeze and your done, they cut into the insulation and of course may well cut some of the strands, and I’m sure they make a cut into a solid wire too.

[ferrailleur]

Originally Posted by PamlicoTraveler

Thanks for all the great responses. I also found these self soldering connectors.

Looks like a great idea to me.

Looks great!
The video is very convincing!

[thinwater]

Originally Posted by ferrailleur

Looks great!
The video is very convincing!

I tested some of these (NTE) and they were horrible. Cold joints and failed heat shrink. QC must be variable.


No way I would use this product category.Too variable. If you want to solder, do it manually and cover.

[Svsumurun]

Originally Posted by ferrailleur

Looks great!
The video is very convincing!

I can't speak to brands , but almost every foriegn car dealership uses this type of connector for approved wiring repairs ... having said that they need to be done right , and thus video isn't showing the right tool even being used, there should be a heat shield on the heat source that heats the joint evenly

[Training Wheels]

Foreign car dealers? British? [emoji15]

[john61ct]

Variability, requiring skills and judgment for success is not something you want in a connector.

Not to mention when pull stress may come into it.

Properly crimped so-called "marine grade", heat shrink waterproof butt terminators, asymmetrical if needed,

built-in adhesive-lined heatshrink as primary, liquid tape as additional if needed.

For little wires like this the right crimper is not even expensive, nor are quality connectors

3M, Ancor, Pacer.

[SV Melody]

Hi


I've installed tens of thousands of those solder sleeves on aircraft electrical systems over my career. There is a little bit of a trick to them and they do require an adequate but not extreme heat source to properly melt and seal. Raychem made the best ones - they also invented the things back in the 60s or 70s I believe, might be wrong - the division of Raytheon known as Raychem got bought out by Tyco some years ago, so Tyco now holds the part numbers and production of the best quality versions. Get the Tyco part numbers from their site and order those from wherever has the cheapest price. They come in boxes of 100 usually. There are all sorts of variations as well: several different sizes to work on wires from 26ga to 8ga, coax and triax terminators, shield drains for shielded twisted pairs/triples/quads, also the type pictured above that can be used as a splice. The main advantage of the aviation-spec Tyco ones is that they have red flux inside them applied on the solder ring. This allows you to very clearly tell when the ring has completely melted and flowed into the wire properly. Others that don't have the flux pre-applied... well let's say I've had not-so-great results with those over the years. They're cheaper and it shows, in my experience. So look for the ones with a red tint on the solder .



A temperature controlled heat gun with the reflector is the most common method. Steinel makes the best one I've ever found and those are what the OEM aircraft manufacturers use in new production, almost exclusively. I've found that they usually will melt and seal in about 7-10 seconds with a perfect 360deg melt and seal with the temperature set between 700F and 800F. Lower than that, you might get a partial solder joint which will come apart internally or have high resistance under load as well as an incomplete seal with the polymer rings so no environmental protections. Higher temps than that or open flame/butane torches, you'll risk scorching/overheating the outer tube and it splits open, allowing moisture and other nasties to get in and ruin your splice. The fumes released from one of those when they catch on fire is extremely bad to breathe as well, so do please be careful.



These solder sleeves, when done correctly with the well-made parts and the right temperature settings on the heat gun, will last for decades with zero problems. Even in high vibration, high corrosion, variable temperature, exposure to oils and solvents... they won't leak or come apart.

[a64pilot]

Originally Posted by john61ct

Variability, requiring skills and judgment for success is not something you want in a connector.

Not to mention when pull stress may come into it.

Properly crimped so-called "marine grade", heat shrink waterproof butt terminators, asymmetrical if needed,

built-in adhesive-lined heatshrink as primary, liquid tape as additional if needed.

For little wires like this the right crimper is not even expensive, nor are quality connectors

3M, Ancor, Pacer.

I don’t think heat shrink butt connectors come small enough, or I haven’t seen them if they do.
That is the issue

[SV Melody]

They don't come smaller than the red/pink 22-18 types. There are white ones that will work for 22-26ga but those do not shrink to seal so there would have to be adhesive heat shrink added to make them as good as they can be. As suggested in another post, for really small gauge wires it may be the best idea to add a small terminal strip tucked away and just use ring terminals.

[Lake-Effect]

Originally Posted by SV Melody

Hi

I've installed tens of thousands of those solder sleeves on aircraft electrical systems over my career.
...

These solder sleeves, when done correctly with the well-made parts and the right temperature settings on the heat gun, will last for decades with zero problems. Even in high vibration, high corrosion, variable temperature, exposure to oils and solvents... they won't leak or come apart.

They sound awesome... but also like something that takes special tooling and some practice and skill to do with repeatable success...? Will this work on normal boat-wire, which doesn't have the heat resistance of teflon-insulated aviation-grade wire?

I also am surprised to hear that this technique is used on larger, higher current wiring as well. No problems of the joint heating with high currents?

What do these little wonders cost?

In defense of the lowly crimped lug or splice - a properly crimped connection is both mechanically and electrically reliable, and it takes about zero skill and 10 seconds, and a proper controlled-cycle crimper can be had for $30ish. No heat or power required, either.

[SV Melody]

Originally Posted by Lake-Effect

They sound awesome... but also like something that takes special tooling and some practice and skill to do with repeatable success...? Will this work on normal boat-wire, which doesn't have the heat resistance of teflon-insulated aviation-grade wire?

I also am surprised to hear that this technique is used on larger, higher current wiring as well. No problems of the joint heating with high currents?

What do these little wonders cost?

In defense of the lowly crimped lug or splice - a properly crimped connection is both mechanically and electrically reliable, and it takes about zero skill and 10 seconds, and a proper controlled-cycle crimper can be had for $30ish. No heat or power required, either.

Well... they're not exactly cheap because they have a similar curse as boat parts do. Take a normal screw, it's $0.03. Add the word "Marine" in front of it and poof! It just went up to $1.59 each. These solder sleeves typically have some version of "aircraft" or "aviation" in front of their name, so they run about a buck a piece if bought by the hundred. I found this:
https://www.mouser.com/Search/Refine...&Ntt=144413460


That's one of the places I order parts from when kitting out an install on an airplane. There's a few other places that carry them as well. As for the heat gun or similar tool, they can be done with a lighter. Mostly. Sometimes. It's totally illegal to do that on a plane and probably not a great idea in general in confined spaces where fuel fumes or other volatiles might be hiding. The cheap little $20 Harbor Freight heat guns will melt them, it just takes longer and is more frustrating. You'll want shore power or a generator - they usually run between 1500 and 2000w continuous on 110/120VAC. I have not seen one that is 12/24VDC but that just means I've not seen one. They may very well exist. Probably more efficient use of power without the conversion loss...


They work pretty well on pvc insulation. This is really the part where it helps to have a variable temperature heating tool. Hot enough to melt the splice, not so hot as to cook off the adjacent insulation. 600F to 650F works pretty well on pvc or light ptfe, it just takes about 20 seconds to get it melt properly. I don't think I've ever seen a wire that got to 800F or higher that didn't have other, much bigger problems in the circuit than a splice possibly melting. I've tried re-melting one of them to remove it when I realised I screwed up and needed to reterminate a wire. It was NOT easy to do and I ended up just cutting the end off and starting over. These things don't come apart without a huge fight and lots of cursing. Possibly some vicious 2nd degree burns.


Anyhoo, use the butt splices if you can. They're cheaper and vastly easier to find out in the wild, plus they do a perfectly good enough job for 99% of the tasks they're used on. The solder sleeves are electrically better and mechanically much better (if done properly, otherwise they're crap), environmentally superior but quite a bit more $$$ and more difficult to install. Depends on the application and your priorities which one is more appropriate. I have huge stashes of all kinds of butt splices. Only have a few dozen random solder sleeves running around the parts box.

[belizesailor]

I had to deal w this exact issue on a crossing recently. The RADAR was unreliable because of a bad splice in extremely small gauge wire. The wire had been damaged during the attempt to splice it. I tried several options, all of which ultimately had issues, but finally had to carefully strip it way back to undamaged wire and do a good old fashioned pig tail splice and liquid electrical tape it. This fixed the issue for the duration of the trip. I did advise the owner that this was intended to be a provisional fix and he should have it properly repaired when feasible.

It is very hard to strip and splice such small wires without damaging them...esp when bouncing around at sea!

[john61ct]

Originally Posted by Lake-Effect

In defense of the lowly crimped lug or splice - a properly crimped connection is both mechanically and electrically reliable, and it takes about zero skill and 10 seconds, and a proper controlled-cycle crimper can be had for $30ish. No heat or power required, either.

Exactly.

For smaller than 22 gauge, I'd def go to a distribution box, bus / block, rather than butt splicing.