120v MIG weld on a 3/8" thick (bevel 60deg)

[Mark @ Everlast]

There is one point of discussion here that needs to be mentioned, and is part of every course of Welding 101. (or whatever bonafied course on welding is taught.)

This is the fact there is a difference in a weld with defects and a defective weld. This is a balancing argument when discussing proper weld technique, and allowable defects. Nearly every weld ever made has some sort of quantifiable defect. These defects may be major or minor. Or it may contain a series of minor defects. But these defects do not have to appreciably affect strength. Of course they do have at least some impact, ever how measurable on strength. But over time there have been millions if not billions or trillions of welds tested, and tried. There are rooms full of researched data. And we are at a point where we can take a look at weld defects to determine if they constitute a defective weld. A tiny bit of slag trapped (inclusion) in a weld does not make a defective weld. But you get more than a certain amount, they will. A weld not welded at a high enough amperage or over a prescribed amperage can categorically be described as a defective weld if discovered because the results of such poor technique are known. An arc strike in some situations outside of the weld area can cause minute cracking under even mild pressure! This is an automatic DQ in many tests. But the tests aren't heartless. They do allow a measureable amount of inclusions and tears etc in a test. They results don't have to be perfect to pass. But in this case, NONE of the welds come close. I've literally have seen better welds from a first week welding student as far tests go. I don't mean to throw off on this test. Not by a long shot. I too am interested in the capability of a 120V machine. But in this case, it was a welding FAIL...pure and simple. Too much controversy has been created though, and I think this proves that there is a great chasm in understanding from what is classified as a good or workable weld. Just because the someone thinks that the weld would not leave pieces of trailer in the road, if that were an axle hanger, I can bet that it would have probably jacknifed the vehicle in the road, and flipped down the interstate at some point.

Keep in mind a weld does not have to experience catastrophic failure to create danger or other failures. One weak link breaks the chain, right? So what if the rest are good? If you have more than one weak link, well...go ahead and use your it to hoist a stump your head with your tractor front end loader and stand under it. That will teach the important difference between weld defects and a defective weld and what you will and won't trust in the future.

 

[Mark @ Everlast]

Here's another point of clarification that needs to be made separately so they are not skipped over by the perusing eye. I think this is indeed a teachable moment.

120V Migs are not evil per se. But it is known that an amperage reading of XXX is needed for welding any given thickness of material. Now don't go take into consideration the overly eager, and well meaning advertising capabilities of any unit. No, I am not talking about that.

Most 120V MIGs, even though they are rated for 120-140Amps top out at 90 amps except for brief "spurts"! Now the question you have to research is what or how much will 90 amps (or less) weld in the MIG process? MIG is notorious about laying down a beautiful bead, but not creating any side fusing. So then the issue becomes "carryable" puddle size too. If the MIG is not capable of carrying a fluid puddle all the way across the width of the bead, then it is too cold. Now in TIG this is different, but in MIG it is a problem because the weld will "spill" over on the sides sort of like molten lava, but not have any fusion underneath. (and you can see that in on of those pictures above where there is a distinct line between the passes...a line may be visible with etching, but shouldn't be so visible like this unless there is an issue with fusion). Also it has to do with wire size selected. 90 amps just to for .045" wire is not even close to enough. Even for .035 it is a little rough do the the speed at which it is deposited. .030 is good, and .023-.025" it is about right. Don't forget that voltage plays into this as well, and a 200 amp machine ouputs a lot more voltage and a higher voltage setting will burn the wire in a lot better than a unit with much less limited voltage output too...in effect compensating somewhat for the amps.

 

[Sodo]

But in this case, it was a welding FAIL...pure and simple

OK thanks some folks got their answer, proven it can't (and shouldn't) be done. OK you guys can ignore this thread now and the rest of us can move on.:jaded:

Mark these welds entire purpose on this earth is to show a quick&dirty but "decent" weld on 3/8 material with no preheat, simply a bevel. What I'm hoping for is that you show how YOU would do it with your 120v MIG.

I have now done a total of 4 test-plate welds in my 40 years "hobbyist career". My illustrious (new) career as the only (and DE ?) forum member who is unafraid to post stuff. I varied the distance between the plates (by bending the nails). I did not want to weld to a backing plate, wanted to see it. Distance between the plates is the full extent of my experimentation, specifically to find the distance that works best. In 15 minutes. Using .030 wire.

Incidentally, proper weld design should never subject a weld to a bending stress like this. Any trailer with welds in bending is rookie design period and that's what members should learn to watch for (and be afraid of). By the time a guy has broken 3 or 4 tack-welds he knows better, and building a trailer is hopefully a few years after learning how to weld. Welds in bending doesn't happen in the production world (actually it does, but not often).

If I had to weld something that faced loading such as this I'd preheat it and weld both sides, and if I could not access both sides I'd gusset it so it can't bend. Probably gusset it regardless. I suspect you know this.

Mark I am hoping this thread can actually HELP some members, and I think they want to see YOU do it.

And to the other guys who want to see it, just how far do you think this will go with only Sodo (and a little DE!) asking. Why don't you (other guys) guys ask Mark to show how it's done? This is your forum, you wanna see it, ASK THE PROS to do it.

 

[downsizingnow48]

I liked what SA was doing with the borrowed 120v flux core machine on 3/16. Still hoping for Chapter 2 on 1/4.

 

[Mark @ Everlast]

I do intend to do a 140 test (our 140E). But I have other pressing issues. My wife is still in recovery from a major surgery so the last 3 weeks didn't afford me any extra time to do these type things with a 2 year old scampering about. Plus my regular Everlast duties along with the extra work load of summer time chores and the fact it is unbearably hot here and my shop tops 110 in the day with the fan on. Perhaps in the next few days in the evenings when the temp drops out of the high 90's outside (80-100% humidty).

 

[Mark @ Everlast]

I liked what SA was doing with the borrowed 120v flux core machine on 3/16. Still hoping for Chapter 2 on 1/4.

Me too.

 

[muddstopper]

Mark, I think one could weld 3/8" with a 120v machine if they are willing to take the steps necessary to insure good fusion. A 60*bevel with a root and cap weld aint going to do it tho. I dont know why anyone would even want to do a bend test if a cap and root where the only welds made to join the two pieces of metal. (Using a small amp machine) I mean, really what have you proven, that the welds would fail, we already knew that. I know it has already been mentioned in other threads, but I guess good advice often falls on deaf ears. Multiple passes could have been made to join the metal together and the results could have had a chance to pass the bend test. Trying to cap a 60* bevel in 3/8" steel, with one pass, with small wire and a low amp machine is almost guaranteed to result in a to cold a weld and poor fusion. Some folks wont listen and will never learn

 

[radioman]

Look - I am glad this thread is started. I have a hobart 125ez and I am NOT a welder. I have NO ONE willing to teach me locally other then going to a welding class.

So I just use my machine to weld up stuff to fix. I hate throwing anything away, and I really hate going into local shops for help. I get scoffed at or get a sorry -too small of a job or charge exhoribant prices. So I repair my own stuff and make my own stuff. Granted I do see the limitation of the 120v machine. I had one part I had to reweld in middle of plowing job in middle of snowstorm at 0 degrees and snow falling in on my welding making it popping while welding. . I worry about the part popping off since its half inch thick metal and the bead is cold and all its doing is acting like its glue at the moment.

So All I hear in these threads from career welders say 120v machine cant do crap instead of showing what is the "right" place or situtations or preferred time to use 120v machines. These manufacturers would not make them if there wasn't a need for 120v welders.

 

[Mark @ Everlast]

Radioman,
I appreciate the sentiment. The problem is, that people don't use a 8 oz tack hammer for jobs that calls for a 16 pound sledge hammer. A 120V MIG is a tool. It has its applications just like a 240V or even a 3 phase welder would have. It would be appropriated for such as light body work, including muffler repair, art work, and sheet metal work. People often want to ignore the limitations though. Sure they are made for use, but for certain applications, not every application. There is indeed a need, but just as people will end up using a pair of pliers for a hammer in a pinch, and in the same way, the 120V can do some other jobs, but not efficiently or well. But do you take a mechanic seriously if you see him using a pair of pliers as a hammer to do a job that requires a hammer? Then would you take welder a seriously if they are doing a job with a 120V MIG that would require a 240V unit? What confidence would you have in what he told you and what confidence would you have in his repair?

 

[MinnesotaDaveChalmers]

Look - I am glad this thread is started. I have a hobart 125ez and I am NOT a welder. I have NO ONE willing to teach me locally other then going to a welding class.

So I just use my machine to weld up stuff to fix. I hate throwing anything away, and I really hate going into local shops for help. I get scoffed at or get a sorry -too small of a job or charge exhoribant prices. So I repair my own stuff and make my own stuff. Granted I do see the limitation of the 120v machine. I had one part I had to reweld in middle of plowing job in middle of snowstorm at 0 degrees and snow falling in on my welding making it popping while welding. . I worry about the part popping off since its half inch thick metal and the bead is cold and all its doing is acting like its glue at the moment.

So All I hear in these threads from career welders say 120v machine cant do crap instead of showing what is the "right" place or situtations or preferred time to use 120v machines. These manufacturers would not make them if there wasn't a need for 120v welders.

I understand where you are coming from - you needed a machine and bought one. I'd bet many guys start the same way.
Your last paragraph seems to indicate pro welders don't give insight on when to use 120v migs. (I'm a part-time pro)

Most of what I've told people in the past is to just follow the guidelines on the machine. If it says it tops out at 3/16" material, then trust it.

I've owned two of the little ones, still have the first. In my experience it is very happy with 1/8" material and small 3/16" on occasion.
Small pieces of 1/4" were ok too (tab or small bracket etc).

For many years I just had the little mig, oxy/acetylene, and a normal ac/dc buzz box. The stick got dragged out for any thick material.
Now I have several machines to choose from and 99% of the time I grab a large machine since it's already set up anyway.

Keep using your small mig, nothing wrong with it. Get something bigger when you can and you'll like that too.