MIG Noob...Questions and Observations

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Hi All,I purchased a Lincoln 140 MIG a few years ago but never got around to learning to use it. I did make a few tacks with flux core, but I have less than 30 minutes under the hood. For what it's worth, I'm a woodworker.I make a product that would benefit from the introduction of steel as opposed to being fabricated exclusively from wood, so I'm beginning my quest to learn to weld. I've read bunches of articles and have watched lots of video, and yesterday I ran my first beads. Here are some observations and questions I have. First, some basic info:I'm in possession of a goodly amount of 3/16th flat bar, 3x2 angle, and some S-40 pipe. The chart inside the welder calls for multi-pass using GMAW. I'm using C-25 and .030 wire.- For my first attempt, I cranked the heat all the way up and set the feed speed at '2'  (~100 ipm). I cleaned to bright steel and beveled the edges to ~45 degrees. I welded the pieces at a 90 degree angle. She wasn't pretty, but I whacked at that sucker with a big hammer and the weld held. I cut the piece perpendicular to the weld to see if the penetration was visible, but I don't have any acid, so I couldn't see the line between the base metal (hot rolled) and the weld. Looking at the rear of the piece, it seems like I got enough heat on the steel. It did seem like I was dumping a lot of metal on the joint, though. I was going very slowly. First question: Is it possible that with bright steel and a good bevel that I'll be able to make a single pass? The item that I'll ultimately weld is not structural in any way. I have no doubt that the weld I created would easily support my body weight, though.- Since it seemed like there was a lot of weld the first time, I turned the wire speed down for the next effort. That was a no go, just a bunch of sputtering and popping... I lost that good crackling sound that I had the first go 'round. I guess it was possible that I was going too slowly the first time...right? I've tried to heed the advice that beginners tend to move too fast, so I was definitely plodding the first time.- I did a few butt welds without as aggressive a bevel. Still, bright steel and a little chamfer. Again, 20 hard whacks didn't break the weld, though I got some bending. The rear of the weld seems to indicate that I was getting enough heat, but who knows. Any suggestions for testing the weld would be appreciated.- I've only used a horseshoe pattern. I'm getting a 'stacked' look (again, not pretty). In some of the videos I've watched, the person doing the welding doesn't seem to be doing anything other than slightly wiggling the gun as the move along. I'm under the impression that technique might be fine for lighter gage material, but that some sort of pattern is necessary for thicker (in my case considering my machine) material. Does that sound right?- I am HYPER PARANOID about protecting my eyeballs. I have a Miller Pro Hobby auto darkening helmet. I've set the shade to 12 at the highest sensitivity setting. Can't seem to quite see the puddle, though. Thoughts on a safe shade and how to tell that I am indeed being safe?I'm video taping everything for posterity. I hope to become proficient enough within the next few months to introduce steel into my product. Maybe that's a little ambitious, but that's the goal.Thanks for providing such a great resource for weldors!Best ~ LIA
Reply:3/16" is really too heavy for a small machine like that despite what the literature might say. Max under real world conditions is 1/8" at best. They get away with overrating these machines because they don't set them up using real world parameters. That said, if it's not structural and all you are doing is glueing metal together, it probably won't matter. real world conditions means using a dedicated 20 amp outlet and no extension cords. If you run on a 15 amp circuit, there are other things running on the same line, or you are using a long lightweight extension cord, your output will decrease, and you won't be able to weld stuff as thick under those conditions. Wire speed is nothing without knowing what voltage setting you are using. To do material this thick you need to be maxed out on the "heat". As far as bead size, a weld doesn't need to be any larger than the thinnest material in the joint. Any more is waste, and in some cases can actually weaken the joint. SO if you are welding 1/8" material, the "legs" distance up and down the material from the corner, should be 1/8". With thin material, this is difficult to do, especially with larger wire. 3/16" is probably a more realistic size. If you are globbing on 1/2" of weld, you really aren't adding any strength vs a properly done 1/8" to 3/16" bead. As far as motions, it all depends. Larger material usually means you need to lay down more weld, thus why more motion is often used. Note that in many cases however weld specs call for stringer beads, not giant weaves, so more motion doesn't necessarily mean a "better" weld. I irritate students all the time by doing a few simple demos. I'll weld one plate with a C or Z shaped pattern. Then I'll do the same thing using circles and one not doing any motion at all. Then I do one bead and switch between all 3 as I continue along. When I'm done, you can't tell the difference on any of them. They all look the same. I tell students to find what works for them, based on the joint they are welding. On filets, I like a C or Z shape. On outside corners, I use not motion at all, just straight across. I seldom use a circular pattern myself other than with stick, or doing demos. I just don't see the puddle as well as I do using a C pattern. As far as shade. Use the darkest shade you can still see the puddle clearly and where you are going. If you are seeing spots after you stop, then you might want to go slightly darker. Note that hood will protect your eyes from UV burns even if it doesn't darken at all. You'll see spots and it will be a PITA for a bit, but you won't do permanent damage to your eyes, assuming you don't weld like this all the time. For mig I'm usually at a 10-11. Tig I run 9-10 on average, and I run a bit darker 11-12 with stick. All depends on the person using it. What works for me may not for you.A few typical issues with newer welders.#1 most go way too fast. #2 most lay down way too much material, as mentioned 1/2" of weld where you need 1/8" is pointless. #3 Most hold the gun way too far away from the work With mig, give the same settings, the closer you hold the gun to the work, the hotter the weld will be. Back off and the weld tends to get "lumpier".#4 Round items are very hard to weld well. Most new welders want to keep welding like they are welding flat plate. With round stock you have to constantly adjust the angle to maintain the same angle relative to a line thru the center of the piece.Post up clear detailed picts of your welds along with all the details like machine, wire size and wire speed, power setting, material thickness etc. The more we know, the better we can help. Once I see your welds, I can go from there. Picts of the back side also helps if we are talking about but welds. I need to see if you are going all the way thru on your 1st pass or not. We can cover testing once you have the basics down. A big hammer really isn't the greatest way to really test welds..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:^^^^What he said.Additionally, if you can't see the weld, your helmet may be bad, your lenses dirty, or you as I need cheaters. I recommend to anybody is back up your autodark hood with a fixed shade. My favorite is the Jackson 411p (made in USA) available at Enco products. It is affordable, and after breakin of the pivots, lasts a lifetime. Comes complete with shade 10 filter, although I would suggest upgrading to a gold plated filter. A cheater fits right behind if needed. And they are extremely lightweight. http://www.use-enco.com/1/1/91255-14...g-helmets.htmlWeld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Originally Posted by DSW3/16" is really too heavy for a small machine like that despite what the literature might say. Max under real world conditions is 1/8" at best.
Reply:An auto hood will protect your eyes at any setting that you use.You might try a setting of between ten and eleven ,it just depends on how dark the helmet is at the different settings.You should be able to see the puddle,if you really want to control it.
Reply:Originally Posted by yoshimitsuspeedI think it's good to separate this into structural and completely non structural. If you need to weld two pieces of 1" plate together that needs to do little more than hold it's self together then a 140 mig can do it just fine. If you are trying to achieve max penetration and strength then I do agree that they are over rated. Still I have tested many welds on 1/4" welded with my 140 and have never had a weld fail. It would be better with a bigger machine but for many things it's good enough. I think it's important to stress to people that you aren't going to get the penetration and strength that you would with a bigger machine but if you don't need that strength then it can do fine.
Reply:Sorry I can't post pics yet. I can't find the cable that goes from my camera to my PC I wanted to answer/address a couple of things that have been mentioned so far: That said, if it's not structural and all you are doing is glueing metal together, it probably won't matter. real world conditions means using a dedicated 20 amp outlet and no extension cords.