Need help with undercut

admin

So I'm currently in a short welding class.  We've been stick welding with 7018 rods at 110amps, on 1/4" plate.  I've been working on t joints.  I was told to do a root pass, then two more beads.  I run my first at 45° with no issues.  I run my second, overlapping that one on the flat side at a steeper angle, with no issues.  Now, my 3rd pass, I'm told should go a little higher on the vertical side, but still overlap my 2nd bead.  I can't seem to run this without undercutting.I've tried ever angle I can, and running slow and fast, but keep getting the same results.  I've tried e's, a straight bead, and whip and pause, with the same results.  My last thought was to turn down the amps, but the instructor says it should be fine.  I'm not getting much feedback from him on what to try, other than to lay my work piece back a little so I'm just " filling in a v shape".  While I CAN do that and have cleaner results, I'm sure not everything I will ever welding will be able to be flipped over.  Any suggestions on what I can do better or differently?  I've attached some photos that show my practice.Thank you!

Attached Images



Last edited by LittleTreeGuy; 2 Days Ago at 09:30 PM.
Reply:Filling undercut is,,, tight arc but not weaving the rod wider than the puddle, not sure how to describe it but its washing along the edge and doesnt have the time to fill.  I dont weave at all with this bead and the puddle is 2x the width of the rod fo it flows out.   The good new is,,, once you get the hang of it hard to do it wrong again. I tried to get it for a forum pic a while back and had trouble. It becomes so instinctive to get rid of it after a while.  If you are using e shape you have to pause at the top to let it fill.www.urkafarms.com
Reply:That looks good cept for that, you will get it.www.urkafarms.com
Reply:

Originally Posted by Sberry

That looks good cept for that, you will get it.
Reply:Use kind of a "J" pattern with the J on it's side pushing the back of the puddle up toward the vertical plate.
Reply:Maybe pause for a quick moment and fill it in with more rod.
Reply:Keep a short arc and spend more time at the top of the weld joint (where the undercut is) that at the bottom as you're weaving.
Reply:A lot of good advice above.Undercut = No Bueno. Slow down a bit at the top and let the puddle catch up and fill the undercut.Practice Practice Practice PracticeLincoln 330MPXLincoln Power Mig 256Lincoln LN-25X Wire FeederMagnum PRO 250LX GT Spool GunLincoln AC/DC 225¼ Ton of Torches OFC-A OFG-AAir Carbon Arc Gouging CAC-AEverlast 62i Plasma CutterIngersoll Rand T-30 14hpInstagram: #Freebird Welds
Reply:Thanks all.  I've been practicing, and still fighting with some undercut.  It's seems like it plagues me more when I'm horizontal welding and it's always the top/high side of my weld.  I think the puddle and my brain are telling me two different things.  LOL.  I need to focus more on staying at the top of the weld just a little longer... but my brain says "if you hold the rod at the top, it will get hot and the puddle will run down below the base metal that i just melted/cut out.  I think it's just going to take a lot more practice for me.  On the plus side, I do really enjoy welding.  Only 2 more days left of my short 50hr class.  Unfortunately, it's all been stick welding so far.  I really hoped it would be equal parts stick/MIG, but at the same time, with the little bit of flux core experience I have, I think if I can get good welds with a stick welder, mig shouldn't be too hard to get dialed in.  Thank you for all of your input and suggestions.  I'll try to get some more pictures of my progress soon.
Reply:No one thus far has mentioned the necessity to remove millscale to minimize the possibility of undercut it seems.https://weldingweb.com/vbb/threads/6...31#post8092031Not saying it is always the fix, but there is evidence for it.

1st on WeldingWeb to have a scrolling sig!



Reply:

Originally Posted by Oscar

No one thus far has mentioned the necessity to remove millscale to minimize the possibility of undercut it seems.https://weldingweb.com/vbb/threads/6...31#post8092031Not saying it is always the fix, but there is evidence for it.
Reply:My first question would be "What diameter rod are you using?" You mention you're running 110 amps, if this is for 3/32" rod you're too hot (in my opinion), if it's for 1/8" rod you're too cold (again, my opinion...).Quality Assurance Manager / CWI / NDT Level IICertified Welder-ASME-AWS
Reply:Go to a flatter rod angle (pointing at the upper plate) and slow down allowing the puddle to fill. It looks bad after the fact in your pics. but slowing down letting it fill won't leave a gouge above the bead. With practice you will be able to use almost any rod angle and not have undercut. You purposely get the flux on the rod to fingernail. When welding thinner material like steel buildings to skids, you can actually turn your heat up and use almost a straight down angle to let the more fluid puddle wash up to the thinner plate. Trying to weld with the rod around a 45 deg. angle is more likely to cause burn through because the arc is focused directly on both plates. Having the rod almost straight up focuses the arc on the thicker material. If both pieces are thick enough you point the rod more on the upper piece to prevent undercut.Last edited by Welder Dave; 12 Hours Ago at 03:34 PM.
Reply:So.... I think I got my undercut almost figured out.  While I thought I was pausing long enough at the top, I really wasn't.  I worked on it a LOT at class today.  I just got some flat plates, angled them toward me just a tad,and kept running beads over beads until I got it sorted out.  Sort of a cursive i pattern with a slight pause at the top seemed to work best for me.  I even ran a few straight beads, just moving slower, and they turned out pretty good.Here are some photos.  Clearly, I still need a lot of practice, but I feel like I'm improving in this aspect. Not sure why, but my pictures are upside down. Lol

Attached Images