Welding Tips and Tricks

I've done a good amount of stick at school and am fairly decent (except for 4G) and have done some MIG welding so I thought MIG welding would be a piece of cake. But unfortunately that is not the case for me and I'm having trouble figuring what voltage setting is appropriate for the different thicknesses and such. For example, I was practicing a 3 run fillet on some 10mm plates at 28.5 volts and while the first pass looks good, the second pass always looks very inconsistent, lumpy and just bad. Is this because 28.5 volts is too high? I've been told it should actually be higher because you're having to fuse not only the base metal but also the previous runs as well. Why is MIG welding so hard for me? Please help me out here. Thanks in advance.

Chad, have a look at Miller's website on welding calculators.
This will get you roughed in, then listen to your Mig welder.
Each welder is slightly different, so make minor adjustments.
It should sound like bacon frying, when you get it fine tuned.
http://www.millerwelds.com/resources/calculators/

http://forum.weldingtipsandtricks.com/v ... =19&t=2527

I feel like I've just decided to walk across very thin ice.

How readily can you transfer the Miller calculator outcomes to other welding machines?

I have fiddled with this calculator quite a bit, and I don't like what it says for my machines. For example, for flux core arc welding, the Miller calculator says for 9.5 mm steel I should be using 330 amps and 16 - 17 volts. My Lincoln 180C does not offer me 330 amps, but I can melt 9.5 mm steel quite nicely (0.9 wire).

Truth is, I can use little calculation tricks to claim I know what amps and volts I am using, but my machine only offers wire speed and a continuous voltage knob, and I really don't know what juice I am welding with.

It is the same with my other welders. On one, I have four rocker voltage switches, and I do know their volts (read it in the manual!! -- must be true (?)), and a continuous wire speed knob -- but it is a 150 amp machine. According to Miller, I can't do what I do.

Now, I accept that Miller know a thing or two about welding, so what am I to make of all this?

Hi Chad, don't let my question about the Miller calculator put you off: do look at it, and try out what it tells you.

Have you cruised the videos and text on the Welding Tips and Tricks web site? I think there is a lot of "unhelpful" advice on the Internet about welding, but that is one site where things seem to be hugely reliable.

Perhaps you could consider doing a batch of single pass welds on various fitups to get your confidence in the machine and MIG processes up. Cut a few welds and have a look at them. Establish a base line, and then go back to your 10 mm plates.

You say, "at school". Do you mean TAFE? (Adult trade school) If so, I am not helpful in asking if you have a good view of your weld puddle and know how effectively you are weaving it. But, if you mean secondary school, then it might be best if you get a mentor who can MIG weld and give you feed back. Cut up some welds together.

Don't give up. Be patient, persistent, make stuff, cut stuff up and look at your welds, and go again.

when looking for weld parameters there's another route besides miller. have you looked in lincoln's procedure handbook?

Hey,

I was taught the wrong way. If it falls off, too cold if it drips of too hot, and go from there. Hard to get a good weld like that, a lot of undercut. I had to pretty much figure it myself. But i damn sure taught all the people below me to the best of my abilities . My advice is to turn the welder right up and try some welds, then slowly bring it down. Keep in mind, any manipulation of the wire at a high setting will likely cause trouble , untill you are good enough to read the molten metal. Run hot and straight .

Mick

weldin mike 27 wrote:Hey,

I was taught the wrong way. If it falls off, too cold if it drips of too hot, and go from there. Hard to get a good weld like that, a lot of undercut. I had to pretty much figure it myself. But i damn sure taught all the people below me to the best of my abilities . My advice is to turn the welder right up and try some welds, then slowly bring it down. Keep in mind, any manipulation of the wire at a high setting will likely cause trouble , untill you are good enough to read the molten metal. Run hot and straight .

Mick

that's a very good way to really learn the machine and process.

"Run hot and straight".

Hot: high voltage -- just below burn through.

Straight?

An experienced weldor can weld with higher voltages than a beginner. Hot welding requires good control of gun angle(s), travel speed, and stickout. On those machines where voltage is controlled with set taps from the power source (DIY machines -- except that Hobart uses these taps, and probably many other manufacturers do, also), the weldor cannot often find the ideal voltage. Now you have to use the wire speed to get the right amps into the work, and switch to the highest voltage you can get without burning through. There she sizzles. (Though some people would say, "Step up the voltage even more, until you get a hiss, like compressed air." I have found this spot, when I go looking, but I weld with the sizzle.)

Please tell us more about "straight". Cheers.

Hey,

When i say straight , i mean no manipulation of the wire/arc like so many are mad about at the moment . Pick line for the wire and go for gold.

Further more, I have a theory as to why your 2nd run looks "bad" It is that it lacks the containment of the plates and resulting surface tension , allowing the molten metal to flow around freely. Remeber that solid wire welding is not a fast freeze method and relies greatly on settings and correct technique to yeild good results.

Mick

Thanks for the chart I'll definitely study that. And mike, can you explain that thing about surface tension in greater detail? I'm not sure what you meant by that. Am I the only one or is mig A LOT more sensitive than stick to movement? I can do vertical up stick with ease but I struggle with vertical up mig! At least the open root runs are easier with mig.

Hey,

Think of a drip of water on a window. A single drip of water will stay in one spot as long as its not too big, if you add more water to the drop, it will swell untill it eventually runs down the window. This is the same as your weld pool, if you keep it small, by moving fast, the pool will sit happily where you put it. It the case of vertical up, the pool is kept small by using a lower setting and weaving/ manipulation .

In the 3 run fillet, the first run is held nicely by the two plates, and the surface of the bead is small, it doesnt "drip" but when you add your next run. (im assuming along the toe of the run on the bottom plate) it has more surface and more chance to sag. So speed is the key here too. The way i was taught (eventually ) was that in a 10 mm 3 run fillet, the first run should be 6mm and the consecutive passes should come out another 4mm each. 6+4=10 ta da!!!. Getting this second run to be a 4mm leg will be an indication of the speed you need to travel.

You are right, it is sensitive, as i said earlier its not a fast freeze process. The pool is like water. Wait untill you do horizontal but welds, then you'll really see it.

mick

weldin mike 27 wrote:Hey,

When i say straight , i mean no manipulation of the wire/arc like so many are mad about at the moment . Pick line for the wire and go for gold.
Mick

I weave everything (except for tacks, of course). When is weaving wrong?

Weaving lets me keep the puddle moving steadily forward, to put it where I want it (control the width, focus heat on thicker steel, fill gaps, etc).

I notice, Mike, that you mention weaving when you explain "surface tension", and keeping the pool small on a vertical up weld.

What I do find '"interesting" is the list of as many as ten weave patterns in some texts (Jeffus L, Welding Principles and Applications 7th ed Delmar Centage Learning 2012 page 81) when I find only one or two necessary in my fabrication welding.

Anyway, I weave, don't go "straight", and I get even, controlled looking welds (most of the time).

Hey,

It could be many deciding factors, for which weave technique to use, such as: they way you were shown, the surface requirements of the weld (depending on welding inspection, my company like a straight ripple look on vertical welds, as opposed to that made by a figure 8 weave) the size of the weld : a 6-8 mm vert fillet could be done in a single run, anything bigger would require more runs, and need a different technique.

Mainly its different strokes for different folks unless you have been told to do it a certain way.


Jack: I was taught to run hot and straight on a high spec job with tight tolerances on weld appearance. Do as we say or you're in the dog house.

Mick

You're not alone, Chad,

Vertical-up MIG is a pain in the ass to learn, particularly for a stick hand. The slag on 7018 chills fast and contains the metal, and that feature is absent on MIG. This amounts to an artificial "suface tension" effect.

On a three-pass T-joint, your first pass is welding in a 90*, and the wetting of the puddle on each side makes it fairly easy to control and get a good bead. If the bead is good, then the second pass is filling a 45*. The wetting on the "base metal" side will be fairly consistent, but the wetting on the first-pass side will be affected by every inconsistency it encounters, and neither side will flow out as evenly. Then, the third pass will have fairly even wetting on the base metal side, but inconsistancies on the first pass side multiplied by the "lumps" from the second pass.

In other words, every inconsistancy in one pass will magnify itself in the next pass.

The painfull, simple answer is practice. Observing the puddle, and becoming it's master, compensating at every move for previous variations in the bead.

I know this sounds like an over-simplification, but without the slag to back up your actions, you really have to focus on the puddle and what it's doing to make a good multi-pass MIG weld.

Steve S

People, seriously, this forum is the single best source of insight into welding on the internet.

I feel so lucky to have stumbled upon it.

Thanks, guys.

It's absolutely our pleasure...

We ALL feel grateful to have found a place where we can ask and share without fear of some jackass running his mouth.

Should that d!ck show up, Jody has given a couple of us regulars the power to shut that bullcrap down, as well.

This will always be a neighborhood, where you can ask the guy next door almost anything.

Steve S