New to welding, bought a Hobart 140, asking for advice on welds

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A few days ago I bought a Hobart 140, a 5 liter tank (75% CO2 – 25% Argon) and 0.030 solid copper wire. I never welded before and have been practicing butt welds on the old floor pans I cut out of my 67 GTO. After setting up my equipment and reading the manual, I read that I should have bought a gas mixture of 75% Argon – 25% CO2 (rather than the mixture I bought) and Hobart tech support said I would get a better weld. I’ll dump what’s in the tank and buy the correct mixture.By looking at the pic’s, any suggestions or advice? Also, I’ve been practicing welding a nut on sheet metal. The rationale for this is that many vehicles back then used a square nut enclosed in a cage to attach the body mounts bolts. I cannot find replacements for the rusted ones I had to remove with an air hammer. I was advised to weld the body mount nuts onto the floor pans. When I practiced the nut to sheet metal weld, I did an ever so slight rotating movement to adhere metal from nut to sheet metal. For this weld, I set the voltage to 5 (max) and the wire feed at around 40. Any advice?Thank you, Jim Attached Images
Reply:for the mig gas, the greater the CO2 content, the hotter the weld will be with more spatter.  Conversely, the more argon content the less spatter, but lesser penetration due to a colder bead.  I'm sure you can use your current gas along with proper technique.  The "typical" mig gas is generally 75%Ar/25%CO2, or sometimes 80%Ar/20%CO2. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:Save the CO2 for thick stuff and use mix gas for pretty stuff. Get some 2 inch wide by 1/8 inch thick flat stock and make Ts, laps, and corner joints for practice. Watch weldingtipsandtricks on youtube. Jody does a lot of mig.You got a great machine there. I love mine!
Reply:Originally Posted by jimmi328A few days ago I bought a Hobart 140, a 5 liter tank (75% CO2 – 25% Argon) and 0.030 solid copper wire. . Any advice?
Reply:Thanks for the help thus far all.By all means I take the learning curve seriously hence the reason I spent money on a quality machine, practicing and seeking advice. A neighbor two doors down the street owns a welding business; I’ll ask him to come over and give me some welding tips – tricks. Perhaps I’m mistaken regarding the copper wire. When the welding supply store sold me the tank and filled it, I requested the 75%CO2 – 25%Ar but I can’t say for sure what they filled it with. Attached Images
Reply:The wire you have is copper coated steel. The thin copper coating simply helps prevent rust on the wire.For thin body work, I'd go down to .023 wire instead of .030. It will give you more fine control over the weld and allow you to lay down less material. 75/25 gas is what you want, and I'm guessing that is really what you have. A pict of the cylinder label would tell us more.Your welds are cold. Welding thin sheet is fairly difficult. With .030 wire it's going to be tough to get enough heat without either blowing holes in the edge of the material, or putting down too much wire. Your machine is however a great little machine for sheet metal body work. There's been tons and tons on here written about the best ways to do sheet metal with mig. I'd suggest you pull up a chair and read. I'm afraid right now I don't have time to retype even a small portion of what has been covered in the past on how to get good penetration while avoiding burn thru and preventing warping..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:I’ll buy a 0.023 spool; I’ll have to replace the drive roll to match the wire, not sure if I can find it locally. Yes, I need to review this site more than I have. Here’s a pic of the tank. Attached Images
Reply:I would feel better if that tank was secured to something rather than just free standing on its own base.
Reply:Originally Posted by jimmi328I’ll buy a 0.023 spool; I’ll have to replace the drive roll to match the wire, not sure if I can find it locally. .
Reply:Those aren't welds, they are big tack welds. I do agree with others on here. Start with some thicker metal like 11ga or 1/8". Use smaller tacks to hold them together. Big tacks like that are less fun to weld over and will leave an ugly lump after you run your bead. For things like butt welds grind an angle into both pieces so you have a groove you are filling into. This helps you get better penetration and a flatter bead.  Once tacked into position practice running beads. Watch videos, ask for tips. Get familiar with what a proper bead is supposed to look like while being run  as well as after it's run. On thinner metal there are times when you have to stitch it together with tacks but you want to know how to run beads and do so whenever possible. When welding sheet metal even if you can run a bead you will want to run a short one so you don't get a lot of metal deformation. Read up on body panel welding so see techniques to minimize warpage on sheet metal. You can run tacks hotter than you can welds. Turning up the heat can help keep your tacks hot and give them a better lower profile. Welding something like that nut, start welding on the nut and then drag the puddle down to the sheet metal. When welding nuts like this you don't need to weld the whole thing but you should run a few beads on every face or every other face. This will get you better hold than just using tacks.Lincoln precision TIG 275Millermatic 140 MIG
Reply:Save your vintage "goat" until you have more experience.  Build some stuff for your shop, practice on an old car hood or trunk lid from the wrecker before you tackle your car.  You don't want to mess up on your car, make mistakes and practice on other stuff until you get the hang of it.  Just don't build a trailer  As mentioned by others .023 wire and C25 gas (75% argon and 25% CO2) are what you need for auto sheet metal.Have you seen the auto "rotisseries" that guys have bought/built?  Would make replacing your floor pans a piece of cake."The reason we are here is that we are not all there"SA 200Idealarc TM 300 300MM 200MM 25130a SpoolgunPrecision Tig 375Invertec V350 ProSC-32 CS 12 Wire FeederOxweld/Purox O/AArcAirHypertherm Powermax 85LN25
Reply:I’ve been practicing spot welds. I take two pieces of scrap metal, drill ¼ inch holes in one piece, clamp the pieces together and fill the holes with weld. This practice is going great and the welds are strong.Here’s what I don’t understand. I’ve been researching info on welding floor pans to the floor braces beneath since this is what I am preparing (practicing) to do. Much of this info show the floor pans screwed (self tapping) to the braces for a tight fit then removed one by one and then welded. This means there are holes in both pieces; so what keeps the weld puddle from falling through the hole?
Reply:Originally Posted by jimmi328I’ve been practicing spot welds. I take two pieces of scrap metal, drill ¼ inch holes in one piece, clamp the pieces together and fill the holes with weld. This practice is going great and the welds are strong.Here’s what I don’t understand. I’ve been researching info on welding floor pans to the floor braces beneath since this is what I am preparing (practicing) to do. Much of this info show the floor pans screwed (self tapping) to the braces for a tight fit then removed one by one and then welded. This means there are holes in both pieces; so what keeps the weld puddle from falling through the hole?
Reply:Originally Posted by jimmi328I’ve been practicing spot welds. I take two pieces of scrap metal, drill ¼ inch holes in one piece, clamp the pieces together and fill the holes with weld. This practice is going great and the welds are strong.Here’s what I don’t understand. I’ve been researching info on welding floor pans to the floor braces beneath since this is what I am preparing (practicing) to do. Much of this info show the floor pans screwed (self tapping) to the braces for a tight fit then removed one by one and then welded. This means there are holes in both pieces; so what keeps the weld puddle from falling through the hole?
Reply:Rome wasn't burnt in a day and it takes time to burn a goat...You got some learning to do firsthttp://weldingweb.com/vbb/showthread.php...elp&highlight=Backed my CATMA over your CARMA oops clusmy me  What would SATAN do ?? Miller Trailblazer 302 AirPakMiller Digital Elite  Optrel Welding HatArcair K4000Suitcase 12RC / 12 VSHypertherm PM-45Rage 3 sawRusty old Truck
Reply:Originally Posted by DonoharmNOT necessarily, if you take the roll out you will see 2 channels for 2 diffrent wire sizes, you may just have to turn it the other way, check this before you buy anything. You will need a smaller contact tip though.
Reply:Originally Posted by Broccoli1the new 140's do not come with the .023/.030 drive roll anymore..030/.035
Reply:Today I welded a repair washer over the body mount hole on the frame where years of rust elongated this area. I have 6 more to go and perhaps a total of 14 depending on rust damage. I used 0.30 gauge wire for this. Before I go on, any advice or criticism by looking at the pic?
Reply:Too cold. More heat..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:I guess I could go hotter, the frame is thick and there would be no burn through. I don’t think this washer is going anywhere though and it won’t be seen.
Reply:Once again, you are not welding, you are tacking. Some times tacking can be enough, I just want to make sure you understand that you aren't welding yet. I definitely agree that you can go with a lot more heat. I have a miller 140 so I don't know how my settings compare to yours but for tacking something like that I would have my heat turned all the way up. Wire feed at about 65 but again I doubt that translates to your welder. For tacking something like that I would probably look at their heat chart and see what was recommended wire feed speed for max heat. This will allow you to lay down some low profile tacks with good penetration and a lot less grinding. Now if you actually get to the point of laying down beads. I don't know how thick that metal is but unless it's paper thin I would still start at full heat and would only start turning it down if I started burning through.Lincoln precision TIG 275Millermatic 140 MIG
Reply:As above, you're tacking, not welding.  You need to practice on scrap for a while so you can learn how to read the puddle and hear the changes that the setting make when you weld.  Short circuit MIG is gonna have a distinctive sound when you've got it right.  Like bacon frying.  You picked a tough thing to start with, thin body panels. You need to understand the puddle and how it will react so you can adjust accordingly.  When I got my tig, the first thing I wanted to do was a project made out of .060 aluminum tubing.  I came here and asked and got laughed away.  I tried it anyway and failed miserably, but I only had to throw some aluminum scrap away.  You're practicing on a vintage car.  Step back, practice, then resume.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Hello All,Today I bought a thick piece of metal and a few washers for practice. I set the voltage to 5 (highest) and a wire speed of 30 to 40 (out of 100). This setting seemed to give me that consistent sizzling sound. Then I ground down the welds and I see what appears to be a uniform piece of metal. Yesterday, a patient of mine (who sounded privy to welding) said to grind down the welds and if I see cracks in the weld, this could indicate that I did not get penetration. I don’t see cracks in the picture posted. What do you all think of this pic?When I think I have the tacks down, then I'll try to do a continuous weld along the seam.
Reply:Yes, the Hobart 140 included a roll of 0.30 flux core wire. Okay, I’ll try the flux core and see what happens. I’m welding on the garage floor.
Reply:You can try the flux core if you want but I think you will have an easier time with the gas. It is a little more difficult to watch your puddle and monitor your weld with flux core and that's the last thing you want when you are welding. If you grind out the weld to look for cracks you would need to grind it out completely. Even then it's likely you would need to break the two apart with a chisel to see how much it penetrated. Whatever the case that's not the top priority on something like that above. You don't need ultimate strength or penetration but you do need a smooth decent looking weld with little to no cleanup. Your tacks should look like small low profile round buttons like this.They should not require any grinding or touchup on something like those washers. Don't move the torch when tacking. Point it where you want it and pull the trigger. Once it's the size you want and burned hot enough to get a little penetration then stop. Something like that washer I would tack in three or four places and then weld inbetween the tacks. I would fully weld it just to reduce the areas where moisture can get in. Personally though I would start with butt welds on flat metal and wait till you are pretty good and comfortable running beads on it before moving on to other stuff.Lincoln precision TIG 275Millermatic 140 MIG