Welds bead off while welding?

I got a question for you gurus. I can't find an answer. I have trailer made of 1.4x4" c channel and I bought it for $300. I literally stole it from the guy. This thing is heavy duty for such a great 5x12' trailer and I really like it. Problem is, the sides are too short and there is no ramp for easy loading. So I fab'd up a ramp and it was all easy. Now I fab'd up the sides made of 1.5x1.5" squre tube and that was easy too (make it higher).

Now here is the odd part when I was trying to mate the two together... My welds literally "beaded" off the c - channel. I prepped it of course by grinding away the paint (i think it's galvanized) and I get white and green stuff coming from it after the weld - now I definitively know it's galvanized. I have welded a lot of galvanized stuff before and had no problem welding it. I just didn't expect something like this. The previous owner also welded the frame together - maybe he is doing something right that I'm doing wrong? I switched to 100% argon and the welds "stuck" but wasn't the best of welds.

Can someone help explain why? I'm not a professional by no means but I get by doing my own stuff. The welder is a Lincoln 255 wire-omatic with 75/25mix. Thanks!

Sounds like your not cutting in, more current less wire. Lots of MIG noobs get obseesed with the sound, forgetting the basics of what actually matters, you need to be penetrating and making a puddle, not just depositing it on the surface. Pure argon is a real bad idea, the CO2 increases heat + penetration, pure argon lessens heat + penetration. The CO2 also sorta acts like a flux and removes crap, pure argon does nothing! Just keeps the O2 away.

You need to grind through any paint + any galv, to pure clean metal at least a 1/2" either side of the weld. The C channel is also presumably thicker, hence causing cold lap aka no penetration, no real weld, just a deposited bead sitting on the surface! It is why migs such a bad idea in non experienced hands on structural work. You need more power, more heat and less wire. It may well be beyond your mig. Its were a half decent 160+amp arc set earns its keep! Its very obvious with arc if your just laying the bead on the surface + if you follow the current guidelines on the rod box, its almost idiot proof to a degree. a 1/8" arc electrode ran at rated currents is kinda a sure fire thing, if used with even the slightest modicome of skill. Its not to say your welds will pass x ray, but they can look pretty rough and still work, mig often looks pretty but has zero strength if laid too cold!

Co2 also does some weird thing with surface tension of the weld puddle surface... none of which matters if you didnt grind the ALL galvy off. Some of it can be a little thicker than others. Grind until you see the orange sparks of steel and then your good to go.

Mig settings are a little weird... wire speed actually controls amperage and penetration more than the voltage setting. But it also controls how much metal is going into the weld puddle... its a weird triangle of stability...
Voltage controls how big the arc is and how fast the wire melts off into the puddle and (kinda) how big the puddle is...Mig is backwards from Stick and Tig; the faster you move the more penetration you get (all settings being proper...)

I have found a technique with mig that lets you fight your way through various coatings with acceptable results...
By stepping the volts by 1.5 - 2.5 for a given wire feed rate and using more of a 6010 like whip and pause( with a little less drastic movements), I was able to burn through pits of paint that a grinder couldn't reach and produce welds that sealed air tight (and didnt look like total crap either ). That job was rebuilding old broken arsed locomotive frames into "new" switch engines for moving freight cars around the yard. If the settings would have been 19volts 280Wfs for clean tight fitting metal, i was running 22.5 volts and 290wfs. I also bumped the gas flow up a little bit. The forward motion would ball up the wire and burn away the garbage. The return flick would "throw" the glob back into the puddle and fill the joint out and let it stabilize back to "normal" short circuit like conditions. It had a real distinct sound when working properly; *Hisssss Buzzzz Hissss Buzzzz*

Zinc Sucks, Best of luck

PlasmaOnTheBrain - I really do appreciate your good pointers. I was running 22V with 200wfs. This metal was giving me trouble and I just couldn't understand why - I can actually see now what could be going wrong. On a side note, I've welded 1" plate of mild steel with my Lincoln 100 (home depot 120v) and it welded just fine. Did it get penetration? No, it did not. Did it stick? Yes it did. My 255 wire0-matic is no chump. Though I don't have the best of welders but it suits my needs just well. I also don't have the money to buy another machine - it's 23yr + machine and I love it for what it is. Best money spent on this machine hands down (for me that is). Cheers!

adama - I will definitely keep those pointers in mind. I'm going to slow down the feed speed and play with the amperage! Can't afford a new machine like yours (assuming you have a wicked setup haha) - this machine can do it but like you pointed out, I'm a newbie and that I'll admit. I've been welding many years now but I still don't know much - welding 1-3 a yr on small minor projects means I don't know squat! This board does help though! Cheers

mpower said:

...I've welded 1" plate of mild steel with my Lincoln 100 (home depot 120v) and it welded just fine. Did it get penetration? No, it did not. Did it stick? Yes it did...

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Actually, I don't think it welded worth a shit..."sticking" is a term I might apply when using glue--it doesn't apply to welding.

My 255 wire0-matic is no chump. Though I don't have the best of welders but it suits my needs just well. I also don't have the money to buy another machine - it's 23yr + machine and I love it for what it is. Best money spent on this machine hands down (for me that is). Cheers!

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The Wirematic 255 is a great machine--we still have one in our shop and use it all the time...

Mpower, i don't have mig here at all, too messy and just not suited to what i do. If you want to reliably weld thicker material you need to get a stick set at small house hold type electrical supply levels. You can pick up a cheap one secound hand for next to nothing in most places. With stick, so long as you have the amperage, weather you weld like a amature or a nuke grade pro all comes down to you not the welding plant. Rods are dirt cheap, sub £10 a 5Kg box over here. Plant second hand i have seen them go for £30. You already presumably have all the protective gear for mig.

mpower said:

I got a question for you gurus. I can't find an answer. I have trailer made of 1.4x4" c channel and I bought it for $300. I literally stole it from the guy. This thing is heavy duty for such a great 5x12' trailer and I really like it. Problem is, the sides are too short and there is no ramp for easy loading. So I fab'd up a ramp and it was all easy. Now I fab'd up the sides made of 1.5x1.5" squre tube and that was easy too (make it higher).

Now here is the odd part when I was trying to mate the two together... My welds literally "beaded" off the c - channel. I prepped it of course by grinding away the paint (i think it's galvanized) and I get white and green stuff coming from it after the weld - now I definitively know it's galvanized. I have welded a lot of galvanized stuff before and had no problem welding it. I just didn't expect something like this. The previous owner also welded the frame together - maybe he is doing something right that I'm doing wrong? I switched to 100% argon and the welds "stuck" but wasn't the best of welds.

Can someone help explain why? I'm not a professional by no means but I get by doing my own stuff. The welder is a Lincoln 255 wire-omatic with 75/25mix. Thanks!

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What dia. wire are you running?

I'm running 0.030 wire.

.030 wire seems small, offhand. How thick is the metal? (C4 with 1.4" flange isn't a standard channel, so I can't look it up.) Your wire may be balling up because the amperage is hi enough to melt the wire, but not hi enough to melt the base metal.

If it's 1/8" thick, you may have better luck with .035, or more than 1/4 thick, .045.

PlasmaOnTheBrain said:

The forward motion would ball up the wire and burn away the garbage. The return flick would "throw" the glob back into the puddle and fill the joint out and let it stabilize back to "normal" short circuit like conditions.

Click to expand...

That's been the key for me, too when welding galvanized. Drag arc forward to burn the coating off, go back to the puddle to make a deposit.

And, don't breathe the stuff if you can help it. Too much, and you'll go blind. It's temporary, but still disconcerting and inconvenient.

1/4" thick. I don't weld too much thick stuff so I don't have spools of 0.035 laying around. I usually buy the spools of 11 lbs and use it till I run out - then order more. Yeah you maybe right - wire is a little thin.

Sounds like a technique issue
Pull the weld along never push
And start at the bottom and travel up
This will take practice and clean steel
Good luck

mpower said:

1/4" thick. I don't weld too much thick stuff so I don't have spools of 0.035 laying around. I usually buy the spools of 11 lbs and use it till I run out - then order more. Yeah you maybe right - wire is a little thin.

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No you can do more than you think is possible with .030 wire. I actually have a feeder with .030 hooked to a 451 Deltaweld all the time in the shop. .030 Wire costs a bit more but is worth it for the arc intensity and not having to deal with a bigger weld puddle than you want welding some things. I won't get into what I have welded with it but in a weld repair shop a lot of different stuff. I run at 24 volts on the dial but also have the feeder set up with a + 50' extension so probably some voltage drop.

Lars66 - great point b/c that's what i've always used for EVERYTHING. I don't do it for a living so I don't really have a lot of stocked items to switch to. I'm a weekend warrior - non professional haha.

I played with the heat setting and I had it at 25volts and around 300 wire speed. A lot of build up in the nozzle which I had to rid of but it welded the joints just fine. I'm going to grind down the welds a little and paint it to protect the steel from rusting and call it a done deal!

at 22 V you might not be pushing enough wire... maybe step it up to 220-230?

What do you mean by they "bead off"? Is your polarity correct? Running in reverse polarity can make a nice looking weld, but as you can see in the picture gets no penetration at all.

I got it working with more wire speed and amperage. I'm not to savvy on this but my welder ground lead is negative. I use it to clamp onto the trailer. I'm assuming the gun is positive? It's been set like that 20+ yrs ago. I never changed anything on it.

for the record
ER70-S-6
22 volts
300 inces a minute

Lincoln electric.com
follow the prompts
they tell you just where to start off with settings

inches
my bad