Properly Crimping a Copper Welding Lug.




Introduction: Properly Crimping a Copper Welding Lug.

About: Hi, I'm stephen, I'm a certified welder, working on my machinists cert, and working part time at a hardware store. Mixing in all of that with my hobbies of blacksmithing and knifemaking, only makes for more...

When you're installing welding leads, a copper lug is very important for attaching the leads to the welder and the ground clamp. Proper attachement of lugs is a must, as they must take a lot of power, and be well connected to the wire to conduct it well, and because they at the ends of the leads, they also take strain from all the movement they will see during their life time. 

Considering this, it's surprising how often I see welders that have lug improperly installed on the leads, most often resulting in the leads pulling partially or fully out of the lugs.

Step 1: Tools

It's rather simple and easy, all you need in the way of tools is -

large flat head screwdriver
and sometimes you might need some cutters for trimming the wire.

Supplies, all you need is the wire you want to make leads from, and a copper lug for your size wire.

Step 2: Stripping

You want to trim the wire to the full length of the lug, remember, you want all the connectivity you can get.

Step 3: Insulator Beveling.

I like to slightly bevel the end of the insulator, letting me push it in slightly for a nicer look and a tighter fit. Just tkae your knife and slightly bevel the end.

Step 4: Fitting.

If you eyeballed it right, then when you push the wire into the lug it will fit nice and snug, and you'll have to really push it. If it's too long, it won't fit all the way in, to short and it will fit in too easily.  In the first photo i stripped it a little too long, so I trimmed the copper a little until it fit in nicely (second photo).

Step 5: Crimping

Set the lug on a hard surface (concrete floor works), and lightly tap the end with hammer to snug the wire. Don't hit it hard, if you flatten it too much it will just push it out instead of holding it. If you do it right, it should hold it nice and snug.

Now, take the screwdriver and put the blade lengthwise on the collar, and drive it in, creasing the copper collar. Do this along the whole collar. I like to also turn it over and slightly crease the backside. When done right, it'll hold forever.



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    23 Discussions

    Nice, simple, clear instructable. What so many naysayers seem to forget is that it's rarely the particular tools you use to do a job that has the most impact on the final results, but the skill with which you wield the tools available. The main advantage of tools like crimpers is that they remove a certain amount (but certainly not all) of the skill needed for good results. I suspect that this method, skillfully applied, is just as good as the "professional" method for the vast majority of applications. Add in a well done solder joint, and you are absolutely golden.

    Worked Great. better then spending 100 bucks for a tool to use only once.


    If you go to a decent welding supplier or quality auto-electrical distributor, they can sell you a proper lug crimping tool. That way you won't have to do a nasty bodge-job with a hammer. You should also use proper cable shears, not a knife when working with wire/cable. I'm sure your a fantastic welder, but you shouldn't really be giving advice to do a job like this mate.

    6 replies

    First off, I'm a professional welder, halfway through my machining degree, and a knifemaker/blacksmith.
    I'm not an idiot who's going to try and cut copper cable thicker than 1/2" with a knife. I was stripping the cable with it, if you read it, you would have seen that. Ask any electrician, using a knife for stripping cable is both a good way to do it, and very commonly done.

    And secondly, I was taught this method by a professional welder who has been welding for many more years than I've been alive, and he has had great success with this method when done right, as have I. I'm sorry if it isn't the "Shteef approved method".

    You do it how you like mate, that's your call. But as someone who trains both domestic and automotive electricians, I think it's wrong of you to imply that yours is the 'correct' method. Here in Australia and also in the UK, if a work place health and safety inspector caught you crimping with a screw driver and hammer or de-sleeving wire with a pocket knife you would be ejected from the work site.

    Your still not understanding.
    This isn't for the professional electrician working in an industrial plant or something. A place like that would have the money to buy the high end quickconnect ends for welding leads anyway, and those attach differently.

    This is for the guy at home who just got the stuff for his new welder and isn't sure of a good way to attach the wire to the copper lug. Most time I see someone who did that, they stick the wire in the lug and hammer it flat. Resulting in it squishing partially out and not being a good connection, as well as failing prematurely.

    As for stripping the wire with a knife, sorry, but my strippers don't fit the large welding leads, and none of the shops around me are about to have strippers that large, and I'm not about to spend $50 or so to get them to order me set, just so I can strip 3 cable ends for my welder. And yes, a knife works fine, and I know plenty of electricians who use a knife for stripping large wire like this.

    oldanvilyoungsmith, Your instructable is much appreciated, I suggest that you save your time and leave shteef with his comments, you do not need to defend yourself.

    A crimping tool for the welding lugs you show in your instructable is available for about $100, cable cutters (which you would use to safely remove the insulation on the cable will cost about $50). If you are having to replace the lug regularly you would have to be doing a lot of welding. Welders, like all tradesman earn pretty good money and can and should buy proper tools for the job(they can claim for the tools when they do their tax return). Therefore a professional welder should use the right kit properly and safely. If an amateur welder is doing this then a safer way of fitting the lug would be to use a lug with a small hole at the other end to the cable entry and holding the cable with a vice, heat the lug with a blow lamp and flow solder into the hole.

    Advising anyone to crimp a terminal with a screw driver and hammer or de-sleeve wire with a pocket knife is just plain dangerous and wrong. As has been previously been stated it may be fine as a one off when your out in the sticks but it is NEVER the correct way to do it. You could probably peel a banana with a chainsaw, but that doesn't make it correct!

    Very helpful. Evidently some folks think you need to buy a hydraulic crimper to do a task that comes up once every several years. But your method works fine for the rest of us.



    This is a very helpful instructable that gives an alternative way of making a crimped connection. I have a car and just about all of the "properly" crimped ground cables on it have failed. Now I have a way, that's in my budget, to work on replacing the failed ground cables. Thank you.

    Pretty much just what I did the other day, when I made up a new earth lead for my buzzbox. Shock, horror, according to the 'expert criticisers' on here, I even made my own lug out of 1/2" copper pipe and drilled a hole in one flattened end. I'm utterly sure it's not going to work loose, as the design of the clamp secures the cable body nicely to the handle and the lug, after being diy-crimped with this method was filled with solder.

    So the Criticisers can go take a long walk off a short pier.

    Perfectly good method for doing the job.

    For all the know-it-alls out there who always have a million objections to everything people post - if your cable pulls out after you've done it this way, you're not doing it right, simple as that! And let's grow up and stop whinging about safety and health concerns constantly - if you're that afraid of injuring yourself, please stop doing constructive things and go sit on your couch and read a book and be quiet! Just be careful - reading books can cause paper cuts!

    Nice job, but I have had mixed results over time with your method. I bought a 'hammer crimper' off Amazon (or Ebay) for under $20.00 that does a perfect professional crimp. FYI

    Also, slip a piece of heatshrink onto the cable before attaching the end. Makes a nice finishing touch.

    For what it's worth, I do battery cables more often than welding cables, and have the correct toggle type crimper available. After crimping, I still use this method as an added clamp. I have more faith in this than a (proper) crimp. Experience in hostile envoronments has taught me to do so.

    I thank you for the post but I have seen the wire move over time with this method and pull out.
    If you wish to know for sure that your lug will be held forever you can take your cable and lug to most electrical wear house supply's or your local power company and they will have the proper crimper and die that will make a perfect hex crimp that will hold the wire from all sides of the lug. And if you only need a couple done they will do it for free.

    Good Luck!

    This works just fine. I have done the exact same thing, only with a chisel many times. No problem, this is not rocket science and frankly I don't give a flip what an inspector has to say about it. Also have wicked in solder on certain high vibration applications on marine and other equipment. Do this along with the fine crimp you made with the screwdriver or chisel.

    This works just fine. I have done the exact same thing, only with a chisel many times. No problem, this is not rocket science and frankly I don't give a flip what an inspector has to say about it. Also have wicked in solder on certain high vibration applications on marine and other equipment. Do this along with the fine crimp you made with the screwdriver or chisel.

    Good Instructable, should work fine.

    This site is about how to fix/make/design on our own. We could all hire to get the work done, or buy expensive tools.

    The method Steven explained could come in useful in emergency situations. If you are a boater like me, you realize that do-it-yourself ability can be a life saver. In an emergency, you never have the perfect tool available.

    As a positive suggestion, I keep a old pair of garden pruners, ("anvil" type, not "shear"type) in my workshop for cutting heavy cable. They will cut 000 gauge (10 mm) copper cable smoothly


    dont listen to these nay sayers, good instructable.

    @shteef and superpants, when has anything on this website been done in a professional manner (aside from critisism) this site is about the backyard builder. doing things a diffrent way to avoid paying lots o money is what its all about. if we all took our stuff to be handled and built and fixed or whatever this site would be called