Need a mig weld diagnosis

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I need some pointers from some mig welders out there...what is going on at the ends of my welds?  I have posted a few pics of a couple of the many welds that i have tried running without luck.  Specifically, why is the end of the weld burning through and creating a crater?  These welds havn't been cleaned yet.  The material is .083 wall square tubing, my machine is a lincoln 140c (110v) and i'm using .030 wire with an argon/CO2 mixture.Any help is appreciated.  Thanks!!Scott Attached ImagesHappiness belongs to the self-sufficient.                                                       -AristotleKill Your Television
Reply:Look kinda odd. I see you're starting to get built up heat and sagging of the base and bead after about 1/3 of the bead to the end. Looks like where you end there's a hole like you were running with a keyhole all the way, but I doubt you were. You would it know if you were. More like the bottom falls out of the base metal. There some porosity or ging out there at the end too, plus the coloring is strange. There's something going on there I can't quite pick out.
Reply:Simple, you can't weld that far on .083. Shorter welds will fix your problem. We used .023 in my basic MIG sheet metal class, that may help. Our max allowable weld length was 1 5/8" IIRC9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:Looks too freekin hot to me.  can ya turn it down or go faster?Less volts will help with the spatter.  Less wire speed will help with the burn through.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:It burns through. That is pretty thin wall tubing, do you know what the machine was set at for voltage and speed? Are you cleaning your metal real nice and shiny beforehand? What amount of gas flow are you running? Do you know if you were pushing or pulling the bead? At the end of most weld beads, I was taught to make an extra circle (or what ever motion you use) with the arc to build up the crater before cutting power. This works good with stick, wire, even tig.(Lots of ineffectual knowledge, with just enough equipment to be dangerous!)Last edited by tanglediver; 08-08-2008 at 10:55 PM.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:I agree with David. Less is more. Turn down the volts and wire speed and perhaps move faster(but don't rush). Also I would run way shorter beads. It looks like you are baking some of the weld in a few of those beads. Welding is not something that can be rushed, it takes time and patience. Never rush a welding job. If something is being welded there is a good reason. Take your time. If this is just practice stuff you may want to get some angle or channel. Something with 1/8 thickness should work ok for what you are doing.Too much head not enough base metal to take it and not enough filler being deposited to fill the hole before it dies.'Mike
Reply:That looks a bit 'dirty' for bare wire and C25.And the spatter says to me you probably had the voltage a bit too high.I think you might actually have been running a keyhole or almost, and that is what you have.In which case you have a bit too much power going on.  To melt all the way through 0.083 steel would take about 80-85 amps.  You may have been running at 90-110 or so, and once the metal warmed up after about 1/3 of a bead, you had too much heat/power in the arc.Notice also the center-line sinkage going on.  And not only the ending crater, but the ending keyhole, and the ending divot where the arc melted nicely most of the way through the base steel in pic 1.I'd say dial the volts and wirespeed (amps) down, and slow down the travel speed.  The best laid schemes ... Gang oft agley ...
Reply:I think all the previous guys have it down pat.On thin material rather than pausing forward movement to fill the crater I'll break the arc by releasing the trigger and then give it a short 'spurt' to fill it in. It almost looks as if you're losing gas at the end of the weld so don't pull away immediately, let the remnants of the gas keep the air away until the puddle solidifies. Or, it could be the burn thru looking like that also....Mike
Reply:They look like too hot fluxcore welds, Are you sure you are using shielded wire?Tim Beeker.
Reply:Thanks guys, I will give it another try today with your suggestions.  I had run some short beads yesterday and they also had the divit at the end, so I will start by turning down the power and go from there.  I'll post the pics later tonight.THANKS to everyone!Happiness belongs to the self-sufficient.                                                       -AristotleKill Your Television
Reply:To me it looks like you aren't getting any shielding what so ever. Try grinding the entire to off one of those welds and posting pics. If it's nothing but porosity, I would say it's a no-shielding issue.Visit Tensaiteki.com
Reply:is your polarity set right? it should be electrode positive for mig and electrode negative for fluxcore welding. i agree it is to hot. but be sure if you are running mig set the gas flow to about 15-20 cfh, and mig does not like rusty metal.
Reply:I agree with what's posted above.  I would check your wire and your gas.  It looks to me like a lack of sheilding as well.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Way to hot...you can see the weld starting to fall through 1/3 way through the bead. The burnt flux residue being so heavy and running so far out from the bead indicates he has ample shielding IMO.Anything worth doing is worth doing RIGHT
Reply:Originally Posted by olddadWay to hot...you can see the weld starting to fall through 1/3 way through the bead. The burnt flux residue being so heavy and running so far out from the bead indicates he has ample shielding IMO.
Reply:Originally Posted by olddadThe burnt flux residue being so heavy ...
Reply:Originally Posted by Another HobbyISnip..... i'm using .030 wire with an argon/CO2 mixture.Any help is appreciated.  Thanks!!Scott
Reply:The huge crater pipe is due too welding too hot and creating an unshielded situation underneath the weld. Huge amounts of hydrogen and nitrogen are absorbed and ejecting during solidification.If you ground the shielded side a little, you would discover gross porosity.In a nutshell - too hot !!! 1.6mm LCS is difficult to weld using MIG. Can be done but takes plenty of practice. Pulse mig is superior to CV current, however I don't think pulsed units are available in 240V hobby units yet for MIG.Keep practicing mate.Cheers
Reply:OK, here are the updates...but first off, thanks again to everyone. I'm getting a better idea how to troubleshoot from looking at my welds and it has a lot to do with the info im learing here.The problem seemed to stem from a couple of problems WAY to hot as everyone stated.  The first welds i did with the welder set at the recomended settings for voltage and feed.  For .083 maerial, the chart called for a voltage of G-H and a feed of 2-2.5.  I guess i was a little shy about straying too far from those settings...the settings for this next batch are in the first picture....much lower!I think most, if not all of the source of the porosity was because I had bunged up the tip. The feed driver pushed the machine end of the welding gun out of its receiver and no shielding gas was getting to the tip...might have been an issue!Anyway, have a look at the latest go and let me know what you think...by no means perfect, but getting better.  I am still getting a bit of a dimple at the end of the weld...I'll have to fine-tune a little more to solve that. Attached ImagesHappiness belongs to the self-sufficient.                                                       -AristotleKill Your Television
Reply:The pictures:PAGE 11. weld settings2. overview of beads as i was changing settings3. weld prep4. bead closeupPAGE 25. bead closeup6. bead height7 - 9. fillet weld and penetration Attached ImagesHappiness belongs to the self-sufficient.                                                       -AristotleKill Your Television
Reply:The welds look more reasonable now.  The spatter is much better, and you aren't melting right through the steel.And they look like MIG welds now!  Amazing what happens when you mess up the gas flow, eh?But now it looks like you may be a bit too cold in the welds.  They look like they are sitting on top of the base steel and not melting along the edges.  Before you had no/insufficient shielding gas, and too much heat/power in the welding arc.Practice, practice, practice.For the ending 'dimple', when you get to the end of the weld bead, pause and then go back towards the rest of the bead.  Don't just get to the end and stop.  Sometimes just a pause is enough, the little bit of motion back towards the rest of the bead helps insure you don't have and ending dimple/crater.Also, flat plate or bar or strap about 14-12 gauge or so is good to practice on.  Thick enough that you can see the edge and have a little bit of time to see and watch the arc as it melts the base material and to see and watch the puddle of weld bead as you go.  A butt joint or a lap joint is good to see the edge(s) melting.  Get a strip of 1/8 inch thick x 1" or so bar/strap a couple feet long and practice the edges/joints with that.  The best laid schemes ... Gang oft agley ...
Reply:Still looks like there is a shielding gas problem- What is the CFH at?Anyhoo...Set  the machine to H-2.5 and start weldin'- while welding, turn the Wire speed UP or Down and listen to the sound. When you get a sweet spot of a Bzzzzzzzzzzzz you are getting close.Or set the machine to G-2 and do the same.On this machine you can also change the Voltage while welding- but it is a wee bit easier to just select a Voltage and change the wire speed.This is one of the problems with a 140 amp Continuous Voltage selection machine- WAY too many variables to adjust- spend a lotta time di-cking around-Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Holy Crap...that 3rd bead in the original post is solid wire ??Anything worth doing is worth doing RIGHT
Reply:Originally Posted by olddadHoly Crap...that 3rd bead in the original post is solid wire ??