help with 7018 lap joint

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hello all. been reading for a while but haven't really posted before. great forum!I need some help. I am currently enrolled in a welding program at college. I've done some stick and mig welding before for fun, but was never very serious about it...now im hooked.passed through wld 101 which was basically to get the feel for running stringers, tie ins, and multi layers with 7018 and 6010 (using 'whip' technique' for 6010)now in wld102, were moving in to joints and positions.i'm having a problem with my root pass with 7018 on a lap joint.i can't figure out if its my rod angle, amperage, positioning, etc. probably a combination of them.i'm running 1/8'' 7018. 120amps with a very slight oscillating movement. sometimes movement just draggingI feel like all of my welds are too 'flat'. this then causes my next two passes to not look so good (they tend to have a dip between them where the root weld should have been - if that makes sense?) and I think I'm getting undercut on the tops of the welds. ive tried going down to about 113 and even up to 127 and haven't noticed much if any difference. obviously, everyone is different, but my instructor had his set around 115 when demo-ing. I got him to show me individually once which helped a little but i still feel like something is just off. its tough as well to keep going to him because we have a very large class.attached a couple pics of one i did last night.could use some guidance! much appreciated.dont mind the poor start/ending points...I did a pretty poor job tacking these together. Attached Images
Reply:I would work on the postion of the rod. Jamm it right into the middle where the two pieces of steel meet, then drag the rod. I'm not sure how wide your instructor wants your beads, but I would narrow that root up ( Travel faster on the drag), then start stacking pass 2 and 3 on top of it. When you go for pass two, aim for the center of the first pass. Then the third pass, aim on top of the second, into the middle of the back plate. It's hard to explain, but you should see where your rod will fit into a little crevice and fill that up. The amp adjustment is up to you for the most part.. What I mean, some weld faster and hotter, while some weld a little cooler and slower. As long as you're getting good pen, and washing in your top and bottoms aka(No Undercut) on this project here you should be good with the amps you are currently running.. I personally would run a little more amps, but that's me..  I'm sure others will chime in..Last edited by ShortbusWelder; 03-22-2013 at 01:25 PM.
Reply:Its all about rod angle.From the looks of it, your pointed more at the bottom plate than the top. Try running at 45 degrees. Then on the next pass make sure it overlaps by half and then the same with the top pass. Keep at it! The only real cure is more time in the welding booth.
Reply:Hello jbriggs33, to have more crown on your root bead you should increase your drag angle slightly. When you cap this joint try to "center" the bottom bead above the toe of the first bead by about a 1/16". This will allow the last bead to properly fill and tie into the top edge of the joint, as well as make a flat transition to the second bead. 45 degree rod angle for first bead, 50 degree rod angle for the second bead, and a 40 degree rod angle for the third and final bead. Good luck and best regards, Allanaevald
Reply:that's not so bad, I would turn it up a little, but that's always my answer.You have some undercut there. When you're welding, watch the very top of the puddle, you will see a small line of molten slag at the top when you're undercutting. When you get it right, that line will go away.
Reply:hey thanks everyone for the replies.I do believe it is likely more to do with my rod angle than anything the more I think about it and the more I read.just to make sure I did not confuse anyone -  this is only the root (or first) pass for the lap joint. I know that the majority of this gets covered by the next two passes, but I feel like my root pass is causing issues with my next two passes. probably not a huge deal since it will get covered up, but I would rather get a good root pass down first instead of just ignoring ugly ones.another thing i forgot to mention - with all my root passes, the slag is ridiculously difficult to remove in most parts of the weld. I have to beat it pretty good just to get it to come off and I know this shouldn't be the case.
Reply:Your rod angle changed about half way across your weld. Keep a consistent angle through your entire weld. Make sure your comfortable before you start and make sure you can do the entire weld without having to change your rod angle to keep going.On a joint like that, I like to hold the rod at 45 degrees, then lower my hand just a wee bit more to push more metal on the upper plate. I also like to run 1/8 7018 at 130-135 amps. The hotter the better, less chance to bury slag.Your travel speed also was a bit inconsistent. Work on keeping that consistent throughout your weld as well.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:A little lower work angle or slower travel speed will put more heat in the weld so the slag comes off easier. It will also help you crown more too.If you know the difference between rod angle and work angle this makes sense. If not it can be pretty confusing. If your facing the lap joint your rod angle will go up and down and your work angle will go left and right. Rod angle is the way your rod faces the joint and work angle is the angle at which you hold the rod to travel. Clear as mud right?
Reply:i think one of my biggest problems right now is the work bench itself. I'm 6'4''. when I find a comfortable position, it generally doesn't allow me to weld freely from one side of the plate to the other...a slightly taller work bench would be amazing and I think help a lot, but since its not my bench, thats really not possible.plus i know that they say you should be able to weld in any position and not to get too 'used to' welding in the exact same position, so i guess im just trying to find the right balance of both. we have spring break next week so i won't have any hood time until the following tuesday, which sucks but nothing i can do about it.