This is just some welding stuff I heard of or have used . .
Reading of a body man who uses Brazing Wire in his Mig . . . Reverse polarity and straight Argon gas . . .
“Greatest thing since sliced bread”, he says . . this I want to try. It sounds like a weeener . . . :-) even less heat in the metal.
While speaking of filler rods or wires . . I use an extra filler rod with the wire welder, where I have a big gap or hole . . You have the welder in your right hand and you feed a filler rod in like you're gas welding with your left hand . .
This filler may be a gas welding rod . . or coat hanger, or even a flat strip that fills the gap . . Copper backing strip will keep it all from falling out on you . .
Even when stick welding . . I've beat the flux off another welding rod and lay it in the bottom of the gap and weld over it . . .
Straight/Reverse Polarity . . . some welders have a switch . .
If it's a stick welder you can just reverse the plugs of the cables .
Electricity . . the little electrons . . flow from negative to positive . . .
In welding, that means with straight polarity, negative work, positive electrode, the heat is hanging in the electrode . . .
Reverse polarity puts the heat in the work instead of the electrode.
With sheet-metal, straight is what you want . . if you're doing some heavy material and want good penetration, use reverse polarity . .
Some stick electrodes don't work except with a certain polarity . .
It was mentioned in an earlier post that you can get a magnetic flux going in a weld area and the weld just seems to blow out . .
This is not new . . . if you run into such a phenomenon, tho I don't know how you will recognize it if you're not already experienced, I used to have to wind the ground cable first one way around the work piece and then the other till I got the flux to cancel out . . sometimes you can just wind your ground cable across the welding cable . . no science . . straight magic . . :-) move the part, say a chant or two . .
Penetration, per se, is in the voltage . . . to control the voltage, pull the electrode farther back from the work . . . that's the electrode your wire is running out of if you got a wire welder/mig . .
Some have asked about the diff between a wire welder and mig . . None is my first answer . . . but now they have flux core wire welders that don't use gas so we would call that a “wire welder” I guess ..
“MIG” stood for “metallic inert gas” was a milspec and AWS designation . . new designation “GMAW” gas metallic arc weld . . further refined this week to “GMAWG” I think, for a “. . . gas” on the end. Don’t quote me . . . :-)
Getting back to the voltage . . when your weld is getting too hot, you pull back a fraction on the electrode . . . the wire will still get to the work, trust me . . :-) you are literally lowering the voltage.
Up-hill welding will give better penetration but also more heat, down-hill the reverse is true . .
Second trick: keep the heat in the heavier or bigger piece of metal, it can handle it. . . you do this by directing it at the edge of the big piece and just flirting with the thin piece . .
How do you know if it's too hot . ? remember the color it was just before it fell out on the floor ? that's too hot . . :-)
Yes the reverse is also true . . if you need more heat in there, get that tip in a little closer . .
The Big Clue : what does a good welder sound like ? a good wire welder sounds like a bee . . a 60 cycle bee . . even a stick welder has a sound like that . . you'll know when it's right . .
That gets us to those corner fillets . . 3 corners at right angles come together . . . farside . . . :-) naw, give you a break this time.
Looking at your wire welding tip, you have the gas shield over the center tip that the wire comes out of . . .
The wire runs out and shorts on the work piece and melts and the gas shields the whole thing from air . . otherwise it just turns into a mess . . bubbles 'n stuff . .
For the Neophyte . . if this were a shielded arc rig . . the one that doesn't use gas, it has a flux, like the stick electrodes, but it's inside the wire . . when the wire melts, so does the flux and it covers the new molten metal and shields it from the air . .
Ok back to the nozzle . . the gas shield thingy . . the tube there .
On flat work, the tip electrode and the nozzle are both about flush, you're running between “need to see” and have to protect the tip from touching anything . . center is the “hot” part . .
With it flush and tipped up about 45 degrees, your tip is about 1/2" from the work . . . this gives you good control of said tip . . Push the gun as opposed to pulling like a stick arc . .
For working in a fillet situation . . a right angle __[, you pull the nozzle back and expose more of the tip so you can hold that 1/2" from the work . .
This is all because of that big nozzle diameter . . 5/8-3/4" .
There are alternatives . . I still have a nozzle from a prior life that is necked down to about 3/8" and is about twice as long as usual.
It also came with a longer center tip so it could still stick out . . This would get you down in those deep corners and still give you the ability to see . .
Check with a local welding shop catalog and see what they have. . . give you an idea of how to make one for your rig . . just slips over your stock nozzle . . .
Gas pressure . . . inside in a corner, maybe 1/2 cfm . . barely flowing . . you have a fan on or working outside, may need 15 cfm . .
Average shouldn't be more than about 4 cfm as I recall . .
Keeping all this in mind, lots of times it is in your interest to put up an air shield between the fan and your weld, just something low.
Spatter Shield: if you don't have some, get some . . it's a spray can of some stuff that keeps the dingle berries from sticking to your nozzle or tip . .
I will describe a good weldor on a job . . he taped a piece of mirror inside a hole, then bent a welding rod into a hook, got in there and stood on his head and welded the backside of this boiler header that was cracked . . it was later x-rayed and found solid . .
While you can't get a mig gun in that hole he was in, there is no reason you can't weld the back-side of things by looking in a mirror. Well . . maybe one reason . . :-)
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