.....Yes Hotroddaddy, that's a great idea to use the 70 series rod AFTER the root pass with the 60 series.
.....Hoof, It's a rod that you just 'drag' when you run it. Just strike your arc, touch the rod to the parent metal & 'drag' it forward staying just a little ahead of your puddle. And when/if you get the 70 series rod I'd get the 3/32" size. It's the size right under the 1/8" rod & because of the fact that the 70 series rod needs to be run hotter than the 60 series you'll find that you'll probably be able to run the 60 series 1/8" & the 70 series 3/32" at the same heat setting. So it's like a double bonus; 1) you don't have to switch settings when you switch rods & 2) the smaller the rod the easier it is to control & guess what??? If it's easier to control, it LOOKS better! ..... Also from my experiences in welding I found
that 7016 is even a little easier to run than 7018 so you might try that. Oh also make sure that everything is clean & as rust free as possible. Oh yeah, for lower amperage settings it's acceptable to use a #9 lens in your hood. This makes it easier to see what's going on verus using the #10... I was wondering something else; You mentioned having a deep gap to fill??? How thick is your frame??? I'm thinking that may be you made your 'V' groves to wide??? All you need is a little 'v' to get some penitatration not a big wide gap. I'm having trouble visulizing a frame that's so thick that it needs multipul passes. I think you mentioned already haveing the frame fabbed up to weld so keep this in mind for next time. Also another thing you can do if you have trouble with the root pass is to only 'v' grove one side 1/2 of the way through the parent metal. Then after you've welded one side, grind through on the other side of the metal to the back side of your first weld pass. Then you just weld a pass on the back side... Am I making sence??? So for your first pass you've used the parent metal as back up & for the pass you make on the backside your first weld is your backup. BUT again, remember you don't need much of a 'v' grove in the parent metal! have a good 'welding week-end' Bill