Not Sure Why

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Today I had to weld some pretty thick aluminum, it was a broken fender bracket for an oil truck.The bracket is mounted to the sill under the cargo tank, at a 45 degree angle. I tried and I tried but welding one side of the bracket was practically impossible. I ended up walking the cup which seemed to work somewhat, but I kept getting interrupted (phone calls, visitors to the shop, etc., the supervisor was out of he shop and one guy is on vacation) so right when everything was getting good I kept having to stop. I'm not sure that was the problem though. I was having a tough time trying to get the torch angle, arc length and operate the foot pedal and trying to see while crouching in a weird position. It was wetting out but taking a long time. There was decent penetration, which is good. The factory uses MIG to weld these joints, and by looking at the broken joint you could tell that there was not much penetration on the original MIG welds. The filler rod was balling up like crazy which I know is bad but I couldn't figure out how to stop it from happening.But when I had to weld the other side, I turned the torch upside down, lit up down the bottom of the joint, and just zipped right up to the top without any problems. It was like night and day.And of course the side that came out nice will never be seen by anyone but the side that looks like Fido is right there out in the open  I was using the HTP 221 with 70% AC balance, frequency at 200, and flat out at 220 amps and foot pedal.1/8" 2% Lanthanated electrode, gas lens and I turned the gas up to 20-30 gph.Material looked to be 1/4" aluminum bracket welded to at least 1/4" maybe 1/2" above the sill of the truck, no way to tell without drilling a hole which is not allowed.Is it possible that because of the angle, the shielding gas was floating away on the one side, yet the other side trapped the shielding gas better?Honestly I am not particularly proud of this job, even though it will be strong enough to hold. But I was having a hell of a time, increasing the electrode stick out seemed to help somewhat.I went through some electrode, the filler kept balling up and falling on the electrode because of the angle, and wicking down the electrode causing a lot of the electrode to become contaminated.Any advice to avoid this in the future would be greatly appreciated. In flat position, vertical position I can TIG aluminum OK, but one side of this 45 degree angle made me feel like an idiot. I will post pics in a couple minutes.Thank you! 2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:I had to upload pics from my phone. Attachments are handled differently on this forum than what I'm used to, so bear with me please. So Upper right pic is the broken bracket, with all of the old weld material ground out and paint sanded off.Upper left is the bracket after being pushed back into shape, lower left is my rigged up arrangement for pushing the bracket in the proper direction for proper alignment. It's not pretty but it sure worked! Lower right is just a pic to show the gap, which is zero gap, the fit up was tight. Attached Images2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:So here are the 2 sides of the same exact bracket. The pic on the left is the Fido side, it was giving me fits and the filler was balling up and just not working out well at all. The pic on the right actually came out OK, I noticed some soot near the top, I wire brushed that away and was able to finish that.Even the Fido bead I was able to somewhat salvage by going over the bead with no filler and melting it over again, I had to really push the filler up into the puddle, at the end I think the filler was getting oxidized.Hopefully someone here can put me down the right path as to what went wrong, I appreciate it.Thanks for reading! Attached Images2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:Reduce your AC freq from 200Hz to 60-80Hz.  Thick-sectioned Al needs a less focused {wider} arc to facilitate puddle formation and promote weld toe wetting.  Also, don't see a need to increase your shielding flowrate above 16-18CFH.  A post flow of 10sec should also be adequate.Above all, ensure the Al surfaces are oil/grit free and clean ready for TIG'n.Last edited by ManoKai; 03-31-2015 at 09:03 PM."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:Originally Posted by ManoKaiReduce your AC freq from 200Hz to 60-80Hz.  Thick-sectioned Al needs a less focused {wider} arc to facilitate puddle formation and promote weld toe wetting.  Also, don't see a need to increase your shielding flowrate above 16-18CFH.  A post flow of 10sec should also be adequate.Above all, ensure the Al surfaces are oil/grit free and clean ready for TIG'n.
Reply:When I had the frequency set at 50 it was even worse lol.And thanks guys for the responses, it means a lot This machine is fairly new to me so every little bit helps.2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:I get that behavior sometimes when two layers come together as in a lap joint. My theory (unproven) is that currents are mixing air into the shielding gas. Putting a backer on the other side helps me. I think it traps gas.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:by the looks of it to me you dont have enough amps behind that both sides look cold to meHigh Octane Welding
Reply:Interesting you say it looks cold. I think the material may have been thicker than I had thought, plus that giant tank pulling heat away, because I had the machine maxed out at 220 amps. I saw the video where Jody welded 1 inch aluminum with the same machine maxed out. Should I think about using helium in the future?2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:preheat
Reply:yup preheat would be a most with only 220amps id probally max the syncro 250 doing that but id rather  just mig it way fasterHigh Octane Welding
Reply:Are you right handed?  I think it was a culmination of a few problems, mainly lack of heat, and poor torch angle.  I don't see any evidence of a gas coverage issue, or anything (the soot at the top was likely external contamination - nearby paint offgassing, missed bit of oil or something, but I'm not going to discuss that.First, not enough oomph for that material thickness.  As a general rule of thumb, 1/4" is going to need around 250 amps, plus or minus a fair bit depending on a number of variables.  On a little part sitting on the bench, you can get away with less, as one can saturate the part with heat, then run with it.  On a big part, the metal is pulling heat away faster than you can put it in, so you need a lot of heat, and that's where the 'more' comes in.Your tank qualifies as a big part, so you simply weren't able to put heat in as fast as it could pull it away.  That is why you were sitting there, and having a hard time getting it to wet in - just couldn't heat it enough.  This is evident as both sides look cold, and the left (as viewed by the camera) looks cold.Secondly, for me, as a right handed person, the forward side of the bracket would be much easier to reach.  With the way I would position myself to reach it, the right side (as facing in the direction of the camera) would have been a cake walk, and the left would have been a slightly more awkward position (I'd likely swap hands and weld with my off hands).  But, my point there is that if that is the case, you weren't as comfortable/couldn't see as well, etc on that first side.  As such, your torch angle was likely suffering.  This poor torch angle, coupled with having to just 'sit' there, waiting on the puddle to form, would be why your filler kept balling/dropping.  By the time you got around to the second side, you had put a little heat into the part, so it had a slight advantage (or less disadvantage, rather), and you were more comfortable, so your torch angle was better, so you weren't balling the filler quite as much.  But, I'd say there's a high likelihood that you don't have fusion to the root on the 'good' side - definitely not Fido's side.  I'd think with what I see, along with what you've said, that you were able to get the 'toes' to wet out, and were able to bridge them, connecting them on the surface, but not actually fusing them down to the root.Who is John Galt?
Reply:I think you may be onto something, I am right handed and I did weld fido side lefty. The angle was very difficult for me, even was hard to feed the filler with the tank protruding out at the top. I def was able to match or better the penetration of the original MIG joint on the "good" side. This is a fender bracket and I am confident it will hold and do its job.Another option I have is a Miller 250x with a spool gun. Would that be a better option for this type of joint? Wouldn't the tank still pull heat out, or is it not as critical? Thanks!2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:spool gun will kill the tig for penetration  on aluHigh Octane Welding
Reply:This is great info, thanks for posting this!I did not know that the MIG would get better penetration than the TIG in this situation.2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:mig alu will almost always have better penitration then tig alu due to the arc charatoristics unless you go into dc alu tig with helium.High Octane Welding
Reply:I will def use the spool gun on repairs like this in the future.I really appreciate all the feedback and help.2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:Originally Posted by massacreInteresting you say it looks cold. I think the material may have been thicker than I had thought, plus that giant tank pulling heat away, because I had the machine maxed out at 220 amps. I saw the video where Jody welded 1 inch aluminum with the same machine maxed out. Should I think about using helium in the future?
Reply:You shouldn't need to preheat with that machine.......For sure go waaay down on the hertz  100 or less....unless there is a draft in the shop 15 CFH  is more than enough gas flow....As far as gas lens......I only use them when there is a access issue and I have to run the tungsten out more than the std cup will give sufficient gas coverage......your good to go with lowering that Hertz.....   Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock