“Never solder vs crimp” logic?

ip485 said:
lw395 - strangely I do wonder what evidence there actually is that proves this form of joint is more / less reliable and if so by how much - https://www.youtube.com/watch?v=HTJ5kEzVvH4. I knwo we have always crimped or soldered, possibly before shrink wrap with a reliable glue core and tinned wire?
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Nasty.
Anything goes to get you home of course.
The final nail in the coffin is the way he makes the 'join' and threads the heat shrink on later.

I've pushed enough motorbikes bodged with that kind of squalor to know better.
 
ip485 said:
lw395 - strangely I do wonder what evidence there actually is that proves this form of joint is more / less reliable and if so by how much - https://www.youtube.com/watch?v=HTJ5kEzVvH4. I knwo we have always crimped or soldered, possibly before shrink wrap with a reliable glue core and tinned wire?
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That's a bodged Western Union Splice, or linemans splice, it should be soldered.

If it was soldered, there's nothing technically wrong with it, but it's a waste of time. A proper, "normal" soldered joint would be just as good for our purposes, as would a properly crimped connection.
 
PaulRainbow said:
That's a bodged Western Union Splice, or linemans splice, it should be soldered.

If it was soldered, there's nothing technically wrong with it, but it's a waste of time. A proper, "normal" soldered joint would be just as good for our purposes, as would a properly crimped connection.
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The point of a lineman's splice is that it holds together under tension while you solder it. smallish wires, people solder them by heating with a lighter and adding some solder. It's excusable if you're being shot at while you need it fixed.
 
I once found a spot welded splice. One wire of a 20 pair multicore changed colour part way down the cable (that caused a bit of head scratching for sure). Not content to let sleeping dogs lie I had to investigate. A couple of dead cats later I found the splice, a spot weld.
 
Lon nan Gruagach said:
I once found a spot welded splice. One wire of a 20 pair multicore changed colour part way down the cable (that caused a bit of head scratching for sure). Not content to let sleeping dogs lie I had to investigate. A couple of dead cats later I found the splice, a spot weld.
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Don't you just love the colour changing cables :disgust:

Recently did a shore power installation that used black and white wires for live and neutral (US colours), but they swapped colours between the incoming socket and the switch panel, then back again when they got to some busbars. Great fun.
 
thinwater said:
Salt.
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I think lw's remark was a little tongue-in-cheek but a joint on a small boat near a diesel engine is in probably the worst environment you'll find on this planet. It has low frequency and fairly high amplitude vibration, moisture, salt, a varying temperature and it's usually not a design that has been carefully thought out for maintenance of electrics and especially for support of cable runs. You'll get little or no help from the manufacturer either whereas a fighter jet or missile will have very detailed instructions of EXACTLY how to make the join.

FWIW it's worth the summary of the best joint is the one you can do the best is about right. Good crimps are harder to do than most people realise but good soldering has to be learnt as well.

If you are really good soldering is faster than crimping if you have a loom to do for example - but that's really not relevant unless you're a professional. Preparation is critical for both types of join as is using the right connectors, sleeves, etc. Get that right and, rather like decorating, the rest becomes a lot more straight-forward. the actual crimp or soldering takes seconds but the prep may even take hours if you have to build in cable supports. The cable should not be under tension, should be supported near the join (and elsewhere along the run too).

The talk of hard points is irrelevant - there's a stress point on both as the crimp and the solder both form a hard spot when the revert back to flexible stranded cable. The trick is to make sure the cable is supported regardless of the type. A lot of people make a fuss about the strength of the join. If that's a consideration then you haven't got the cable run right - the joint is all about electrical connectivity, not physical. Also don't bury the cable in the middle of a loom if you can avoid it - the trick is to keep the cables neat and well-supported but also easily accessible if you need to get at them again.

If you solder use good flux and lead solder but clean the residual flux off afterwards if you've been a bit too keen as it can be corrosive. If you crimp make sure you have the right crimps and crimpers for your cable and that you get the crimp on the bare conductor along the whole length of the main part of the crimp. If the crimp has a portion that lightly crimps the insulation (I don't like that but some do) make absolutely sure you're using the right crimpers. When you strip the cable make sure you don't nick any of the strands regardless of how you join.

Make sure you cover the joint completely with heatshrink with a suitable adhesive under the tube (some come with the adhesive already in the tube and some crimps actually have a heat shrink tube pre-loaded with adhesive already one them). It is possible to shrink heatshrink with a lighter but a hot-gun or similar is much better, especially if you're not used to doing it. It is possible to overheat shrink and the result will be a tube that perishes quite quickly. One tip is to put two or even three pieces of heatshrink on the wire before joining it if you are concerned about using a dodgy heat source. That way you least get a second chance to try and get it right.
 
grumpy_o_g said:
I think lw's remark was a little tongue-in-cheek but a joint on a small boat near a diesel engine is in probably the worst environment you'll find on this planet. It has low frequency and fairly high amplitude vibration, moisture, salt, a varying temperature and it's usually not a design that has been carefully thought out for maintenance of electrics and especially for support of cable runs. You'll get little or no help from the manufacturer either whereas a fighter jet or missile will have very detailed instructions of EXACTLY how to make the join.

FWIW it's worth the summary of the best joint is the one you can do the best is about right. Good crimps are harder to do than most people realise but good soldering has to be learnt as well.

If you are really good soldering is faster than crimping if you have a loom to do for example - but that's really not relevant unless you're a professional. Preparation is critical for both types of join as is using the right connectors, sleeves, etc. Get that right and, rather like decorating, the rest becomes a lot more straight-forward. the actual crimp or soldering takes seconds but the prep may even take hours if you have to build in cable supports. The cable should not be under tension, should be supported near the join (and elsewhere along the run too).

The talk of hard points is irrelevant - there's a stress point on both as the crimp and the solder both form a hard spot when the revert back to flexible stranded cable. The trick is to make sure the cable is supported regardless of the type. A lot of people make a fuss about the strength of the join. If that's a consideration then you haven't got the cable run right - the joint is all about electrical connectivity, not physical. Also don't bury the cable in the middle of a loom if you can avoid it - the trick is to keep the cables neat and well-supported but also easily accessible if you need to get at them again.

If you solder use good flux and lead solder but clean the residual flux off afterwards if you've been a bit too keen as it can be corrosive. If you crimp make sure you have the right crimps and crimpers for your cable and that you get the crimp on the bare conductor along the whole length of the main part of the crimp. If the crimp has a portion that lightly crimps the insulation (I don't like that but some do) make absolutely sure you're using the right crimpers. When you strip the cable make sure you don't nick any of the strands regardless of how you join.

Make sure you cover the joint completely with heatshrink with a suitable adhesive under the tube (some come with the adhesive already in the tube and some crimps actually have a heat shrink tube pre-loaded with adhesive already one them). It is possible to shrink heatshrink with a lighter but a hot-gun or similar is much better, especially if you're not used to doing it. It is possible to overheat shrink and the result will be a tube that perishes quite quickly. One tip is to put two or even three pieces of heatshrink on the wire before joining it if you are concerned about using a dodgy heat source. That way you least get a second chance to try and get it right.
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The most sense I have read about this. Ever. Thank you.
 
"......a joint on a small boat near a diesel engine is in probably the worst environment you'll find on this planet. "


Very true, well, apart from the wiring loom on an old 650 twin British motorbike. :D

Bit of drift....

I had a shortfall in the length of heavy battery cable and had to join in a length. Tricky job.
A 10mm brass, compression fitting did the business; proud of that one ;-)
 
PaulRainbow said:
That's a bodged Western Union Splice, or linemans splice, it should be soldered.

If it was soldered, there's nothing technically wrong with it, but it's a waste of time. A proper, "normal" soldered joint would be just as good for our purposes, as would a properly crimped connection.
Click to expand...

That was one of the ways I was taught many years ago. It was originally used on non insulated telephone lines (we still have then in rural areas of Africa, they had ceramic insulators on the pole cross beams,

In the old days, before my time there were no heat shrink and solder was not easy in the bush.

A Lot of modern stuff is of cause better at it makes it easier and quicker to make a joint and can also be more reliable.

I can remember doing solder wiped high tension cable joints covered in tar to protect now we have clamped and epoxy resin insulated/sealed joints. No bucket of heated and molted tar to burn you.
 
In may be tongue in cheek - but maybe not - we tend to do many things the same way just because it has been instilled as good practice, but I still wonder with glued shrink wrap whether the Union splice isnt just as reliable? Have any tests actually been done I wonder?

I know it is lazy but I did have one join (I know exactly where it is) that is now many years old, totally exposed to the elements and hasnt poved any problem. I recently took it apartment using a digital multimeter first to test either side of the join, and then cut off the shrink wrap. There were no signs of any issues what so ever.

I do wonder whether soldered or cripped joints are in fact any better, or we have just convinced ourselves they are?
 
Rogershaw said:
That was one of the ways I was taught many years ago. It was originally used on non insulated telephone lines (we still have then in rural areas of Africa, they had ceramic insulators on the pole cross beams,

In the old days, before my time there were no heat shrink and solder was not easy in the bush.

A Lot of modern stuff is of cause better at it makes it easier and quicker to make a joint and can also be more reliable.

I can remember doing solder wiped high tension cable joints covered in tar to protect now we have clamped and epoxy resin insulated/sealed joints. No bucket of heated and molted tar to burn you.
Click to expand...

Yerbut...
Telephone cable for stringing between poles is a whole different kettle of fish! Isnt it copper coated high tensile steel? It will maintain its twisted together shape much better than plain or tinned copper. Also there is strain relief across the join in the form of spiral cable grips.
 
You can get away with all sorts of squalid connection when the current is very low compared to the size of the wire.
When you've got plenty of volts to overcome a bit of surface trouble.
A telegraph line carries low current for its size, because resistance needs to be low.
You get horrible things that twist mains cables together in low power things like desk lamps.

12V is often more demanding than that, a bit of surface oxide on the copper will cause heating. You need pressure to get proper metal-metal contact.
A telegraph line provides pressure on the metal interface, because the line is always under catenary tension, often a significant % of the working load of the wire. The Western Union joint may be more subtle than first meets the eye.

If you squeeze the wrapped copper wires hard enough, you could create crimp. But it's uncontrolled, big risk either not forcing the copper together or cutting halfway through it.

One form of electrical connection I've done is compression bonding. Take a wire and bash it into the surface of what you're joining it to under high pressure, so it cold welds into the surface. Doesn't sound great does it?, but it works for gold wires onto silicon chips....
 
lw395 said:
You can get away with all sorts of squalid connection when the current is very low compared to the size of the wire.
When you've got plenty of volts to overcome a bit of surface trouble.
A telegraph line carries low current for its size, because resistance needs to be low.
You get horrible things that twist mains cables together in low power things like desk lamps.

12V is often more demanding than that, a bit of surface oxide on the copper will cause heating. You need pressure to get proper metal-metal contact.
A telegraph line provides pressure on the metal interface, because the line is always under catenary tension, often a significant % of the working load of the wire. The Western Union joint may be more subtle than first meets the eye.

If you squeeze the wrapped copper wires hard enough, you could create crimp. But it's uncontrolled, big risk either not forcing the copper together or cutting halfway through it.

One form of electrical connection I've done is compression bonding. Take a wire and bash it into the surface of what you're joining it to under high pressure, so it cold welds into the surface. Doesn't sound great does it?, but it works for gold wires onto silicon chips....
Click to expand...

Yes, the logic seems right in some way (of course) but with mulit strand tinned copper wire carying relatively small loads is the twisting really any less effective? I only ask, as I say because I wonder if any long term tests have actually been done? It seems to me that often the greatest problem is any form of corrosion between the wire. I have seen this plenty of times where non tinned wired is used using crips or solder and a small contamination of water has found its way into the joint. It all turns green and the resistance shoots through the roof before you know it - of course, it has been poorly done. As we know tinned wire suffers from these problems a great deal less, and if the shrink wrap is also glued along its entire length the risk of water ingress is eliminated so the join remains clean and dry and tightly bound together by the effect of the shrink wrap. It would seem to have the advantage of being completely flexible as well, which was the OPs question, with no hard points.
 
Unless the air is completely excluded, the tinning will still oxidise.
Tin oxide is a semiconductor, loads of research you can look up about that.
You only need a tiny amount of heating at the interface to create more oxide, which will give more heating and a vicious circle.

I'm not aware of any actual research into this sort of bodge, but I've seen wires twisted together catch fire after working fine for several years.
 
lw395 - thats is a very good point - but wouldnt the tin still oxidise when crimped and infact would you not have two different metal then in contact? Isnt it likely the surface area effectively bonded together with a crimp would be much less than the total contact surface area with mulit strand being wound together over some mm's. Just wondering about the physics of what is actually going on? As I say i know it is conventional wisdom .. but? Sometimes joins in the way I am mentioning are of course dreadfully done, and I totally accept if there is a key, it is in the shrink wrap being properly applied, and, I would suggest it being lined with heat activated glue which beads out at the ends to indicate a good seal.
 
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