I never paid much attention to my ground clamps until my welder started acting up, and then I noticed a spark at the ground clamp. Ten minutes and very little money later that problem appears to have gone away! Click image to enlarge

Replacement Ground Clamps

Consistent contact = consistent performance

Text, photos and video by Tom Hintz

Posted - 6-27-2011

Too many of us (Yes, me, too) don’t give our welders ground clamp a second thought. Our assumption is that because the manufacturer factory installed a ground clamp that it should be right for the job, at least initially. The problem is how will it work months or years later? The best guess is – a guess. Its performance is influenced by how much you use the welder, what you are welding and how you prepare the materials. With the heated downward pressure on pricing these days manufacturers are not giving anything away just to be nice people. That includes ground clamps.

The Symptom

I first became aware that my ground clamp was deteriorating when my MIG machine started having sporadic issues. I am aware that I am not a pro welder so my initial suspicions were that I was doing something dumb. There always is that possibility but I was pretty sure that my MIG was at least partially responsible. I looked all over the machine itself, took my MIG gun apart, and replaced the contact tip and the inconsistent loss of welding power continued. In fact, it got a little worse.

After seeing a spark at this grounding clamp (left) I started paying more attention to them. then I saw the replacements in this story and figured that had to be a better plan. The solid brass jaws on this replacement (right) have erased contact problems since it was installed. Click images to enlarge

Then I was welding something else and was facing the ground clamp when I seemed to lose at the wire. At about the same time I noticed a spark at the ground clamp. So, I shut the machine off and looked at the ground clamp being the master of the obvious that I am. The cable connection itself seemed tight but I took it apart and cleaned it anyway. Then I noticed that the contacts within the jaws had dark, pitted areas at the likely point of contact. Since I had seen a spark at this clamp I guessed that at least some of this could be carbon which can be a pretty decent insulator if you give it a chance.

I took a wire brush to the contacts and went back to welding. Either I suddenly became a more consistent welder or my MIG was enjoying a much better circuit with the clean contacts. That improvement lasted through several weeks of my part-time welding before the inconsistency returned even though the ground clamp did not look nearly as dirty. This time I wanted a more permanent fix so I started looking at aftermarket ground clamps, most of which are made by folks who also make welders.

The Copper Look

The more conventional of the two aftermarket clamps featured in this story has a definite “conductive look” thanks to the copper exterior. As I suspected this clamp is stamped out of steel and then copper plated. Despite the steel core the copper plating has to help the conductivity somewhat and its 300-amp-rating supports that assumption.

The copper plated clamp (left) is a step up from the standard clamps in many cases. This one has done well on my Lincoln Pro-Mig 180 Welder. The all brass clamp (right) would seem to be better yet and sure seems to be acting that way on my Lincoln AC225 stick machine. Click images to enlarge

While the overall size of this stamped grounding clamp is normal, the spring that applies closing pressure to the jaws is not. Both of the clamps in this review have substantial closing springs for a reason. Pressing the rounded contact points onto the metal with more force probably isn’t going to improve the electrical connection very much on its own. However, that additional pressure and the tendency of the rounded contacts to pivot or slide on the metal will help them to dig through surface contamination that we should have wire-brushed off before starting.

The actual wire connection on this grounding clamp is simple but solid. You probably will have to cut the welders grounding lead back just a bit to expose clean wire but is a small price to pay for a more consistent electrical connection.

It’s all Brass

The second grounding clamp takes the core material up a few notches. This old-school-looking clamp is cast from solid brass which bodes well for dependable connections and lots of electrical flow. The manufacturer is confident enough to give this grounding clamp a 400-amp rating which should handle all of the home/hobbyist welders needs with ease.

The closing spring also has lots of pressure that squeezes the long, curved jaws tightly onto the metal. The relatively soft all-brass composition means that this clamp will do a little better at establishing a good connection on its own. When you give the jaws a quick wire brushing like you should be doing anyway that connection is better yet as is the flow of electricity.

Both replacement clamps have substantial cable connectors (left) included. The both also have substantial closing springs (right) that help insure a good "bite" at the jaws. Click images to enlarge

The traditional no-foolin’-around engineering of this clamp found its way to the wire connection as well. Give it ½” to ¾” of clean wire and the crushing bolt and pressure plate will maintain an electrically solid connection.

In the Shop

I did a little welding with both my MIG and stick welders with both set near their high power limit and the factory-supplied ground clamps still attached. Then the new aftermarket clamps were installed. The stamped, copper-plated 300-amp model went on my Lincoln Pro-Mig 180 Welder and the all-brass 400-amp clamp on my Lincoln AC-225 Welder. I went back and did some more welding with both machines still set on high as with the original grounding clamps. Unlike some modifications there wasn’t much of a change with either machine.

Better grounding clamps are more to prevent deficiencies rather than instantly improve performance. I’m not usually an everyday welder so the real proof will show itself in coming months. I can say that with my Lincoln Pro-Mig 180 Welder I did a bunch of welding on a scrap-based practice bit of freeform art that had given this welder fits in the past because of surface contamination and odd angles at which the grounding clamp had to be applied. I purposely did not brush the metal off but rather just put the new ground clamp on and pivoted it a couple times back and forth to let it develop its own connection. It worked great and the welder remained very steady.

So far with three days of going back and laying another weld whenever I had a free minute, the Lincoln Pro-Mig 180 Welder is sizzling along just fine, something it wouldn’t do for more than a few minutes at a time with the factory clamp. Not real scientific but it has made me happy and since I paid for all this, that is the important part to me right now. In recent months I have also been getting some email from folks who had replaced their ground clamps and also noticed more consistency in the stable functioning of their welders.

Conclusions

Improving the ground connection just has to help any welder because we depend so much on the flow of electrical power through the closed loop that a welder has to establish to function at all. It just stands to reason that a better connection has to help. If that help comes in the form of a reduced susceptibility to surface contamination, that is still a step up that could help new as well as veteran welders lay consistent beads.

With street prices of just $8.99 for the copper plated steel model and $15.99 (6-27-2011) for the solid brass clamp this bit of preventative upgrading isn’t going to break the bank. If you are a beginning welder installing one of these ground clamps is a cheap way to build-in more stability for your welder which means it can fake you out less. If you are a pro welder I suspect that you have already done the clamp switch thing. If you haven’t we won’t tell anyone that you did now.

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