root pass trouble and "arc control"

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Tonight in school I retook the 1G bend test.  I had passed it a month ago, but with easter break, and with being out with a hurt back, I hadn't been in school for awhile.  Anyway, 1/4 metal, 3x3 inch coupons, 60 degree angle 1/16 root opening, 1/16 land on the groove.  I started with 1/8th 6011 for the root pass set at around 80amps. Started good, had a good keyhole, but then it got away from me, started blowing holes in the work.  Adjusted my amps down to 70-75 (can't remember) but still couldn't keep my key hole from turning into a horrible universe devoring blackhole of death.  I let that one cool, started another one with 3/32 6011 set at around 55amps. It was better, got good penetration, but not much of a keyhole.  Once the first one was somewhat cool, I cleaned it up and filled in the hole and just started working both pieces.The first piece passed the bend test, despite the hole I had to fill, didn't get a chance to bend the other.  Do yall think I was running too hot on the first one?  It seems like everyone else was running 1/8 rod, and every other welding machine I saw was set up around 90-100amps.  My travel speed was fast, and I don't think I could have went much faster.  I was running just a stringer for the root, no whipping, weaving, just swearing.The only other thing I can think of, is maybe I didn't put 1/16 land on the groove. Now that I think about it, I just eyeballed it, so maybe it was more like 1/32 or something.I sure wish I had the Miller XMT 304 I use at school here I home, though  The arc is so much more smooth than on my old AC machine.  If I tried starting 1/8 6011 at 70 amps here at home I'd stick it to the work a dozen times I think.  The machine at work has a knob labeled "arc control."  I've not messed with, as that I don't know what it is for.  Could someone explain it to me?OLD miller M-295  (AC)Century 230/140 ac/dcVictor torchNot much else but some cheap tools.
Reply:I will try.Turning the arc control UP makes the puddle freeze faster and makes the rod dig a little more.  (crisp)Turning the knob down makes for a flatter bead with less spatter. (buttery smooth)Try it at both extremes, then in the middle.Keep messing with it until you can see what it does to your weld.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David RI will try.Turning the arc control UP makes the puddle freeze faster and makes the rod dig a little more.  (crisp)Turning the knob down makes for a flatter bead with less spatter. (buttery smooth)Try it at both extremes, then in the middle.Keep messing with it until you can see what it does to your weld.
Reply:The arc control changes the 'slope"  of your amps/volts curve.  When set low (soft) changes in arc length only make small changes in amperage.  When set to crisp increasing arc length will decrease amperage.  Push in close and the amperage goes up more.  This helps when you are running your root allowing you to whip and pause along.  In effect you are changing the amperage of your machine by having a long or short arc.  When running on the flat with iron powder rods (E 7014) you will find a soft setting is better.  Not to rag on your instructor but you should have understood this in your theory classes before you went under the hood.  Not understanding the theory lengthens your time in the booth.
Reply:Remember that you don't always have to turn your amps up/down with stick - just keep a much shorter arc length and that will decrease your voltage.  The longer the arc length the more air resistance = more heat.  Keep the end of the rod right down close in the gap and you won't burn through as much."A winner isn't someone who doesn't lose, a winner is someone who doesn't quit."
Reply:1/16" opening?  Try a 1/8" land and root opening running around 65-70amps with 1/8" and keep the rod in der!  Crank the arc force for the root and turn it down to around 30%-50% for the rest.  Any reason for running 6011?  I've never actually tried 6011, we've always rooted with 6010.Last edited by mb_welder; 04-18-2009 at 05:22 PM.
Reply:65 to 70 amps, 1/8 rod, nickel wide land, dime wide gap is how I was taught 30 years ago. It has always served me well. 6011 is an AC rod while 6010 is a DC rod. Same rod, different flux. Practise, practise, practise. I'm real partial to DCEN.Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.                                         -Cree Indian ProverbSA 200 LincolnVictor Torches
Reply:Originally Posted by z0diacRemember that you don't always have to turn your amps up/down with stick - just keep a much shorter arc length and that will decrease your voltage.  The longer the arc length the more air resistance = more heat.  Keep the end of the rod right down close in the gap and you won't burn through as much.
Reply:Thats Bull**** my man, I assume your paying for this class, If you're keen to learn this Instructor should be willing to spend the time at least another 1&1/2 hours to accomadate you and any others who may want to learn rather than swilling 2.4 beer.  I agree with z0diac.
Reply:I didn't get it right the first time, 6011 is actually AC/DC, where 6010 is DC only. 6010 will also run on AC, but it ain't purty!! You need to do it like the instructor says, don't mean that's what you'll be doing in the field, or how you'll be tested prior to the job. Could be he's teaching you to pass a test that one of your local shops/jobs require. You'll get there, hang in!Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.                                         -Cree Indian ProverbSA 200 LincolnVictor Torches
Reply:Originally Posted by ol' Stick GuyThats Bull**** my man, I assume your paying for this class, If you're keen to learn this Instructor should be willing to spend the time at least another 1&1/2 hours to accomadate you and any others who may want to learn rather than swilling 2.4 beer.  I agree with z0diac.
Reply:Thanks everyone for the great advice!  I tried several of the suggestions tonight, and did not create blackholes of death in my root pass.  Shortening my arc worked really well, though I felt like I was going to push my rod through the gap.  DCEN ran beautifully, and left the perfect amount of penetration on the root pass.Bent a sample on vertical up.  The root up passed, but the root down failed with a tiny, tiny crack at where the toe of the weld would be.  I think I did not pause long enough at the toes and locked in some slag.  Either way, I was pretty happy with the root pass.Thanks again for all the help.OLD miller M-295  (AC)Century 230/140 ac/dcVictor torchNot much else but some cheap tools.