Crimping large cable lugs without a crimper

says...


I've been a pro the business too, for decades. Still am in fact. And I've never seen solder joints simply deteriorate over time for no reason. If exposed to weather or chemicals, yes. But then even a triple wrapped tube socket will come undone if you leave it out in the rain for a few years.
Jim
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Lloyd E.

But I didn't say, "for no reason". A solder joint never exposed to heat, oxidation, or mechanical stress will last virtually forever. That's not the case with joints in most 'normal' physical environments.
A tour through the insides of an old BC-458 will give you a good look at how well soldering can be done for _rugged_ use. An old "Silvertone" Sears TV will show you the opposing case study.
LLoyd
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Sponenburgh says...

And I've got a half dozen atwater kent radios that have been well used over the years. They all use simple lap joints and none of them have any degradation.
Look the properties of lead tin solder are well known. It doesn't cold flow, it doesn't work harden. If something is attacking lead tin solder chemically, wrapping the wire around the terminal a half dozen times isn't going to help. The joint's still going to fail.
Solder joints rely explicitly on the mechanical properties of the solder to form a gas-tight joint. Think about it: if the mechanical connection has a chance to take *any* strain then the gas-tight nature of the joint's been compromised.
All that mil-spec gear looks great (and I love the aroma, too) and it was a great idea to quantify the skills and train the solderers in a uniform fashion. But the joints are excessive IMO.
Jim
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| Soldering, correctly done, is probably the best method for electrical | conductance, but solder isn't an acceptable mechanical joint. In many code | jurisdictions, soldering is prohibited -- mostly because many people won't | or can't do it well, but also because of the mechanical weakness of the | joint. | | They always taught us in electronics schools, "Make a secure mechanical-wrap | before soldering; solder isn't glue." | | LLoyd
I stayed out of this one to see what would come up, but what I've seen and worked has yet to be mentioned, so I'll offer my experience:
1. Cold joints started out as bad from the very beginning. It's only by luck that they passed through life without causing a problem, so it's not a matter of _if_ they fail, it's when. Only when corrosion and moisture can work its way down inside the joint defect will the mechanical contact that got the joint by for so long will send the joint into final electrical failure. You can go a long way towards not having cold joint problems by using eutectic solder (63/37) which doesn't have that temperature zone the joint passes through where movement will cause crystallization and separation of one component of the alloy. I can't recall for sure which component has a lower melting point (tin?) that will crystallize. 2. What we often call a cold joint is really an incomplete flow of the joint, in other words, a bad fillet with insufficient wetting. The flux can't be removed from inside the joint, so eventually the above failure mode pops up. Often there's a mechanical failure involved, too. Flux has this lovely habit of attracting moisture, which is why the flux must be removed. Acid fluxes are very bad for electrical and electronic connections for similar reasons. 3. Stranded wires and soldering are rarely a good idea unless the wire connection can be supported. If soldering stranded wires, a heat sink should be used to prevent wicking of solder up inside the strands of the wire. Where the rigid solder-soaked strands stop and flexible wire begins there will be a spot highly prone to fatigue, and a guaranteed place to break. When soldering stranded wires to terminations for whatever reason, you MUST provide mechanical support, either in the form of a shrink sleeving, mechanical support such as ties or clamps, or whatever suits the application. It's more expensive tooling-wise to crimp wires, but the strands have an evenly tapered flex section that distributes mechanical movement over a larger part of the wire, thus reducing fatigue. Soldering solid wire strands to a terminal is no big deal, usually, since the wire itself is the mechanical support, but only in purely static equipment will solid wiring ever be used. It's also a lot harder to work with, as many know. 4. For the sake of welding cable, flexibility and high current capacity is the reason for the high strand count. The less strands you have for a given outside diameter the less circular area (thus ampacity) and less flexibility you have. Since the individual strands are that much smaller, crimping is even more critical due to the lower individual strength of the strands, which will flake away at a soldered joint where the wicking ends. You can support the wire all you want, but for the hassle of keeping the wire from wicking and providing mechanical support either way, crimping is the more reliable way to go hands down. 5. When the solder joint itself is the sole point of mechanical support, the solder alloy will fatigue, work harden, and fail just like any other metal will. Since the solder is so much softer than the metal it's joining, the conductor needs the mechanical support (either inside or out of the joint) to prevent the solder from being a stressed part of the connection. Electronic technicians are familiar with large components on circuit boards that must have mechanical support to keep things from ripping apart. I recall capacitors on an A-4 upper beacon which was always coming in with broken solder joints. I started securing it with a tie and RTV and never had one of my own repairs ever come back to me. How the A-4 managed to have a service life of over thirty years and not have that corrected baffles me still.
I really like what's called copalum splices and terminals, even for copper wire, because the intense pressure actually causes the aluminum to flow into and around the wire completely, making a 100% sealed and perfect connection, but they aren't cheap and the tooling even worse. The high quality of the connection is the reason they're used for aluminum terminals, since the lack of any resistance or corrosion entry point prevents any thermal movement which causes fatigue and fires and gave aluminum wiring a very bad name. The terminals allow aluminum wire to work to its best adantages.
If I made a boo-boo or need correction/clarification somewhere, by all means have at it!
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This thread is almost over and everyone will go home without anyones mind being changed. But I will put in my bit anyway.
I think making a mechanical connection before soldering is usually a good thing. Not because it is needed after the joint is soldered, but because it prevents any movement while the joint is cooling. You all have seen the frosty look of a joint that was moved as the solder solidified. So I agree with Jim that a mechanical joint is not necessary, but it may prevent a " cold ' solder joint.
And then I agree with Carl too. A solder joint is only so strong. If it is being mechanically stressed very much it will fail. But if the solder is only supporting a short bit of wire, the stress will be well below the yield point of the solder, and you won't have any fatigue problems.
And I think the reason you should not tin stranded wires being held by screws, is not so much that solder cold flows, but you do have thermal changes to contend with. You get the solder deforming when there is expansion, and then oxygen can get in when there is contraction.
Dan
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I like that and I also like Lloyd's suggestion of grinding a bolt cutter. I would try to make triangular notches in the bolt cutter, if I did that.
As far as soldering. I guess for larger cables I need to use a propane torch. Is that right?
I also wonder if I could use my welding machine somehow.
Thanks guys. A $150 tool is out of question. Maybe I would rent one, but rental prices also are quite steep.
I am thinking of a welded contraption made from steel angle, that I would insert in a vise. Ascii art follows
Top side: A piece of a T formed rolled steel.
U U ========
Bottom side in cross section:
| | ___| |___ ======== Bottom side seen "from the side":
|~~~~| |~~~~| |XXXX| |XXXX| |XXXX|-|XXXX| ============= Top piece would be inserted between the sides of the bottom piece and compressed with a vice. The lug would be placed into the opening of bottom piece. It will be compressed from top to bottom, while being restricted from the sides.
Looks like a nice evening welding project. I have all parts for it.
i
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Or O/A. The trap here is that as you try to solder the joint, the solder simply wicks up the stranded wire and leaves you with a dry joint and effectively solid wire.
The trick is to mechanically compress the sranded wire so capillary action cannot wick the solder up the line.
For smaller stuff I use a stainless hemostat.
Jim
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I recently had to solve this exact problem with zero budget and no time at all. My workaround proved remarkably robust. I had to butt join two welding cables, the light-gage kind used with smaller machines (don't know the number, sorry). I cut a short piece of 3/8" soft copper tubing from the end of a roll I have, and as it was tough to get over the wire, decided it needed the ends formed outwards slightly like two mini-funnels on the ends. I took two 1/2" ball bearings, set on on a bench block, held the short tube vertically touching the top of the ball, put the other ball on top of the tube, and then tapped the top ball with a hammer, driving the balls together. This did just what I needed, put a neat little flare on both ends at once. Then I was able (just) to slide both (stripped) cable ends into the opposing ends of the piece of copper tube. Then I just put the tube in the bench vise and squashed it. It isn't particularly pretty, but it seems quite strong. You may be able to see the joint in the picture on this writeup, although a ground clamp is attached to it:
http://www.tinyisland.com/arcBlowFix.html
I don't know if this would work for the OP or not, but it worked well for me.
GWE
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Could you use parts-store battery cables? Even WalMart sells a considerable variety of lengths for not much more than the cost of the wire.
jw
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wrote:

No, they are too long.
i
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If you're crimping welding cables, have a look at those crimping "jigs" that you hit with a hammer. They are under $20 and can be found on ebay and on the web. These were specifically designed for welding cables.

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I am thinking about cables that would serve inside a welding machine, and see relatively little tugging and bending after installation. These, I think, I can crimp myself.
For actual welding cables, I decided to pay a professional to crimp them properly, as they see plenty of abuse.
i

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On Thu, 13 Oct 2005 18:11:19 GMT, the renowned Ignoramus25589

For those, solder and a crummy crimp (such as a cave-in the barrel or even (ugh) squash the brazed-barrel) may be just fine. I'm assuming they won't see much use and very little vibration.

Yes. The only thing worse is when they see a lot of temperature variation. We have made tens of thousands of high-current cables for high-end injection molds, and the crimp and material selection were both critical to lifetime.
Best regards, Spehro Pefhany
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On Thu, 13 Oct 2005 14:44:45 -0400, Spehro Pefhany

Well, there will be relatively little vibration, but they will be used to conduct electricity. Just very rarely, if ever, touched or moved.

Yes... Here, if they do not fail, I will be fine. Now, if the crimp does fail, and the welding lead falls someplace in the inside of the machine, that could create a hazardous situation or even destroy the welding machine.
So, I need a reliable crimp, but it would not necessarily see much stress.
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Food for though: How much will a conductor will move that is carrying a couple hundred amps every time you strike an arc. Magnetic fields can be pretty strong at high current.
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Ignoramus25589 wrote:

Perhaps just purchase a set of replacement dies for the expensive crimpers and operate them in a large vise or hydraulic press. Should give you the legit crimp for a lot less $ and time and effort.
Pete C.
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message

I've used the clamping bar from a flaring tool in a pinch....
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On Thu, 13 Oct 2005 15:50:16 GMT, Ignoramus25589

$15.75 is too expensive? One that will crimp 8 gage to 4/0 using a hammer is that price from
http://www.sjdiscounttools.com/ezrb790c.html
For a photo of it, download the catalog at http://www.ezred.com /
and look at page 17.
I have one of these, or one a lot like it. It works fine. Use a big hammer.
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wrote:

that would work fine with me. Thanks. I will check it out.
i
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One on e-bay http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&itemu53991294&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1 Don
Ignoramus25589 wrote:

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