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I need to cut a very small damaged section of a welding machine grounding 16mm² cable to remake the connection, but I only have those smaller pliers which likely won't work for cutting it.

I was thinking about using an angle grinder to avoid buying big pliers or a cable cutter just for this one time use, but was wondering if it's possible and how clean of a cut I can expect to achieve using it.

IanC
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    I mean.... With a steady hand you can easily cut copper with an angle grinder... But why? – Matthew Oct 27 '21 at 04:06
  • @Matthew Just to avoid buying a new tool that I'll rarely use, since I don't have big pliers or a cable cutter for a 16mm cable. So the angle grinder came to mind, but I was not sure if it would be a clean cut since the wire is made of tiny strands – IanC Oct 27 '21 at 04:18
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    Try it. Or stick it in a vice (not too tight) and try a hacksaw. – Steve Wellens Oct 27 '21 at 04:32
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    Main problem with cutting cables with a angle grinder is that the cables tend to move around unless clamped/anchor to something. A hammer and chisel(cold, metal) will work also. – crip659 Oct 27 '21 at 10:45
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    Wait... you're skipping out on an opportunity to buy more toys, er... tools??? – FreeMan Oct 27 '21 at 12:04
  • What do you mean when you say "those smaller pliers"? A bog standard pair of diagonal cutting pliers, or even just a lineman's with a cutter, will cut that with no problem. Everyone has one of those in their toolbox, no? – J... Oct 27 '21 at 12:24
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    I understand what type of cable you're cutting through. Yes an angle grinder with a cutoff wheel will work, but to get a clean cut I'd put the cable into a vise or clamp either side with vise grips to keep the copper strands together. A hacksaw would be more difficult on the stranded wire. You could also try a tube cutter if you have one. – Phaelax z Oct 27 '21 at 13:18
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    I have this kind of pliers, so not really suitable for a 16mm cable. I thought of a hacksaw too, but for stranded copper cables I thought the angle grinder would give a cleaner cut – IanC Oct 27 '21 at 13:31
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    @FreeMan I usually look forward to buying new tools, it's just that I'm doing some body work on my car and already spent my "monthly tool fund" on other stuff haha – IanC Oct 27 '21 at 13:32
  • @FreeMan I probably should fix it and add the square symbol, but it's 16mm², so the diameter is close to 5mm or 1/5". Still kinda thick for the kind of pliers I've :/ – IanC Oct 27 '21 at 13:53
  • @IanC Did you try those pliers? 16mm2 is about the same size as 6AWG - 4.5mm across (or just under 3/16"). Those should do just fine. – J... Oct 27 '21 at 17:44
  • @J... I didn't try, but they look a bit small for the job (and mine are not that sharp since they are old). I thought they would chew the cable too much, so I just went straight to the grinder – IanC Oct 27 '21 at 22:17
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    Nobody suggested an axe? – gnicko Oct 27 '21 at 23:17
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    I'd just use an axe, copper is soft and if the axe is sharp it will cut cleanly. – Jasen Oct 27 '21 at 23:39
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    Here imagining an electrician getting on site with a big axe. I don't have one but maybe I could have tried with my machete :p – IanC Oct 27 '21 at 23:45
  • I have a small hatchet, bur no machete, but a machete should work too, possibly even better, – Jasen Oct 28 '21 at 00:04
  • I think many big box home improvement stores have cable cutters available for rent. – Z4-tier Oct 29 '21 at 17:18
  • At a certain gauge, that's the only way to cut them unless you want to buy a thousand dollar cable cutter or sit there with a hacksaw. I'm sure I could... YMWV. The hard part as always is not nicking the wire when you cut the insulation. – Mazura Oct 30 '21 at 03:14

6 Answers6

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So I decided to be the guinea pig and just see how it goes. I fixed the end portion of the wire on my vice, not very tight so I wouldn't damage it, leaving just a tiny piece of it out.

Wire on vice

Then I used the angle grinder with a thin cutting disc and approached the wire close to the vice, not using any force at all, just approaching it slowly and it cut through it pretty nicely. There was a couple strands that were left out which I finished cutting with the small pliers I had here. Never mind the color at the end of the strands, I cut too close to where tin/lead solder was applied, so the very tip of the strands still have it.

Final cut

Then after removing the isolation so I can crimp the new terminal:

Finished

So verdict: Yeah, if you don't have the pliers it's possible to make a clean cut on the cable with an angle grinder, not that I'm recommending it :D

IanC
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    Great answer. Not I have used bolt cutters. I acknowledge a lot of people don't have 3' bolt cutters but the 1-2 times a year you need them, they come in handy. – DMoore Oct 27 '21 at 22:32
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    What sort of disc did you use in the grinder - grinding, cutting, or 1mm stainless cutting (the very thin discs) which I would vote as being likely to give the cleanest cut due to speed and low heat. – John U Oct 28 '21 at 12:31
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    @JohnU I used a thinner cutting disc for stainless steel (I think it's the 1mm one or maybe slightly thicker) – IanC Oct 28 '21 at 18:29
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    Kudos on the POIDH! – J D Oct 29 '21 at 06:31
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    @JD If I was answering my own question, might as well do it as detailed as I can haha, also been kinda using photos a lot lately to keep progress and ask for tips on the repair I've been making on my car :) – IanC Oct 29 '21 at 22:10
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    @IanC Brother, I hear you. I take videos all the time so I can remember what I did. I have an old stove right now that I disassembled that I'm opting to replace half because it's old and has a leaky valve, and half because I went a little gung-ho on disassembly and refinishing. I'd probably put it back together if I didn't have like 50 screws in a bag – J D Oct 29 '21 at 23:18
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    Never ever solder wires that are going to be clamped, that might very well be the original cause of your issues. Solder tends to creep when under pressure, therefore you may never put mechanical stress on a soldered connection. When you crimp on a soldered connection, the solder will creep creating bad contact, sparking and heat. Other than that, feel free to cut the wire with what you've got. I'd first grab a simple hacksaw personally. – Naftie Bakje Oct 29 '21 at 08:56
  • Clamp first, solder last. – Tim Oct 29 '21 at 10:08
  • True, it's good related info! The cable was stock though, I believe it was soldered after clamping. I redid the connection just clamping, didn't really add solder to it this time, maybe will do later – IanC Oct 29 '21 at 22:07
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Once I clamped the cable with an old hose clamp then sawed through the clamp band with a hacksaw - was reasonable but still "furred" or spread the ends.

I purchased a decent cable cutter very soon after.

Solar Mike
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    Exactly my worries, I didn't consider the hacksaw because it felt like it would be too brutal on the strands. Thought maybe with the angle grinder I'd be able to get a clear cut, without spreading and damaging the strands, but not sure – IanC Oct 27 '21 at 13:33
  • @IanC Angle grinder will definitely do a cleaner job than a hacksaw. – yo' Oct 30 '21 at 10:58
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What I do for cutting large stranded copper wires is to drill a hole in a 2x4 that is the OD of the jacket, slide the wire through and cut against one side of the block with a fine tooth hacksaw. The strands stay held together by the fit in the wood block and the finish is very clean.

spicylad
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If you have a rotary tool, like a Dremel, you can use those cutting disks and have a much cleaner cut. It's the same principle, but with greater control and a finer abrasive to leave a smoother cut.

You could also try an oscillating tool. If you happen to have a carbide blade, or simply one with small teeth (or possibly an abrasive blade), you'd likely get a better cut than a grinder. As an aside, I bought an oscillating tool just last year and I don't know why I waited so long. It's absolutely worth the cost, it's just so darn useful. I'd say I don't know what I did without it, but I actually do know just how frustrated, bruised, cut, etc. I was doing things without it. Not to mention how time consuming it was trying to find ways to cut things without one, and the tools and blades I broke using them incorrectly or awkwardly.

If you want a really clean cut, you could try a sharp wood chisel and a hammer, with a wooden backer for the cable to sit on. You'll likely need to sharpen the chisel again afterwards, though.

Regardless what tool you use to make the cut, if you aren't cutting through the insulation, wrap the cable in strong tape to hold the smaller wires in place and make your cut through the tape. This way the strands cut, instead of bend.

computercarguy
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  • I have a rotary tool (biggest reason my "monthly tool funds" are gone haha), I even thought about using it but I thought the higher rpm of the angle grinder would make a cleaner cut on the strands. But I think the rotary tool would work fine too! – IanC Oct 27 '21 at 22:20
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    @IanC, clean cuts aren't just about speed of the cut. Part of it is control of the cut and how aggressive the cut is being done. Most grinder wheels, including the cut off disks, are pretty coarse grits. The cut off disks for the rotary tools are a fine grit and it's a lot easier to control, plus the thin-ness of the disk can increase the speed of the cut. Just like a chop saw, the finer teeth of the blade can make a cleaner cut, even if it takes longer. – computercarguy Oct 27 '21 at 23:03
  • a rotary tool (or a real die grinder) will have more RPM than an angle grinder, but the angle grinder has a larger blade and is therefore faster at the edge of the blade. – Jasen Oct 27 '21 at 23:20
  • True! Maybe next time I'll experiment it with the rotary tool, might be even easier :)

    @Jasen I think it depends, I have the smaller angle grinder that goes up to 13k rpm, my rotary tool isn't top model or brand (not a Dremel) so I'm not sure it goes up to that speed

     – IanC Oct 27 '21 at 23:38
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Is the cable solid core? If yes, just cut away.

But given its 16mm2, I assume its stranded wire. Use cutting pliers* and cut only as many strands as you can in one go. If you get stragglers, you can just trim them like a hedge.

*those that look like heavy short scissors, not the ones with gripping flat surface.

PS If you are really pressed, you can use actual office scissors [you don't care about] to chew through the cable.

Thomas
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  • The cable is stranded and the pliers I have are those, so I'd have to buy the correct ones. Wouldn't the angle grinder be less damaging to the cable than the office scissors though? – IanC Oct 27 '21 at 13:37
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    For stranded copper, even thick strands, some really cheap side cutters (cutting pliers) would do the job, 1 strand at a time if necessary, and would cost next to nothing. You'll curse them next time you use them though, if you go too cheap – Chris H Oct 27 '21 at 15:35
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Sure; for stiff cables (particularly armored) using a cut-off wheel makes for a great, clean cut - quicker and cleaner than a hacksaw or jaw-tool based cutting

enter image description here

Image retrieved from gearloft.com - it is purely to visualize a cut-off wheel and not an endorsement to run your grinder with the guard this way round/the wheel pushing the work

Cut-off wheels are very thin, 1/32 and 1/16 and cut quickly but you should take care to secure the work and keep a steady hand; if you twist either the grinder or the work and the work grabs the wheel it can easily destroy the wheel. You might find it preferable to use them in a cordless grinder that isn't quite as aggressive as an AC one. If you drop/kick your grinder over while it's wearing a cut-off wheel, inspect the wheel carefully for damage, and consider removing the wheel for transport/before you put the grinder in your tool bag - it's just so easy to bash it and ruin it; they aren't expensive, just dangerous if they fly apart as a result of damage

Also, not that I'd recommend you make a habit of it, but accidentally using a cut-off wheel on a cable that is still powered up is less likely to have any long lasting effects on your health or your tools; i've seen jaws of plier type cutters burnt and ruined, and the operator having received a nasty shock, by chopping hot cables but the cutting wheels are non conductive, so they tend to just cause a short between the cores as they grind dust from one core to another. There's a pop/flash, the breaker goes and you live to tell the story; just don't jerk away in surprise (because hitting yourself with a spinning grinder isn't ideal) - mentally prepare yourself with a "I know i made it dead, but just incase someone powered this back on, there'll be a popping sound that I won't react violently to..." thought as you cut..

Caius Jard
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  • I hadn't thought of the lesser risk of shock, that's a good point! Not something to rely on, but still something good to have if you or anyone else in the shop happens to screw up – IanC Oct 29 '21 at 22:16