undercutting flange with mig

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Hello folks,Just a quick intro: I am a welder for a mid sized fence company, I started off as a laborer installing fences and taught my self how to weld on the companies machine after my work day was finished.  Been welding for them 4 years now. In my quest for the perfect weld I'm looking for some constructive criticism on my work.-------I'm fillet welding 1/4" thick plates onto 2 1/2" and 3" SS40 fence posts. (this is for a 10' tall fence inside a warehouse.) I'm doing 19 of them.I tack the plate in position and roll the pipe as I weld it.I started with a C shaped weave, but after experiencing major undercut on the plate I switched to pointing the gun toward the plate(instead of centered between the 2 pieces), slowing down on the plate, and traveling farther before dipping quickly down to the pipe.This helped a lot but I still have a little undercut (pic #1), I would have tried spending even more dwell time on the plate, but it was 6:00 friday night and I called it a night, I'll finish the rest monday morning.In the past I've either lived with the undercut or used a lower setting(pic #2). I've never had a weld fail but I'm not happy with either of those. The lower setting looks nice, but weld thickness does not equal pipe thickness. I have have no idea how I would stress test something this large.Questions:#1 Does pointing the electrode more toward the plate than the pipe undermine penetration of the pipe?         Followup: Should I maintain a fixed electrode angle, (in relation to the V shape of the joint) or should I wiggle the gun a bit so it is closer to a right angle with each surface.#2 The only technique I know for preventing undercut is more dwell time to allow the puddle to fill more. But if I dwell to long won't the puddle will just droop down off the plate and create more undercut? What other things can I try?millermatic 185 with .035 Innershield NR-211-MPVoltage 4Wire speed about 37(this is what the dials say, what does this translate into? I don't see anyone here calling it that)Thanks Attached Images
Reply:The only technique I know for preventing undercut is more dwell time to allow the puddle to fill more. But if I dwell to long won't the puddle will just droop down off the plate and create more undercut? What other things can I try?
Reply:The NR211-MP will work better for that and give you less trouble if you get down on the side and roll the pipe down so that you are welding uphill. Use a side to side weave back and forth. Pause on the sides and quick across the middle. It will also help eliminate the bug holes. You run it just like you would 7018. The pause on the sides is what eliminates the undercut. You can do it on the top as well. I will try and explain the technique but won't swear as to it being understandable. On the top step forward on the pipe then backstep up onto the flange, come back down on to the pipe stepping ahead and then repeat the backstep. Turning the heat up would help a lot but that machine limits you. It's really not quite big enough for material that heavy. Max power will help, but it won't run there for very long. .The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:You can always do something like a J pattern.  I'll try and describe this as best as I can.With wire pointed directly into the middle of the joint, move forward slightly, then backward, but with a little whip upward to fill any undercut at the back of the puddle.  Repeat.  If you stay at the top too long, it can sag, but if you're not there long enough, you might not be able to fill any undercut that is created.
Reply:You could also run a smaller pass and maybe use a two pass fillet so as to get what you think is the appropriate amount of weld on both the plate and the pipe. Not all welding needs be done in a single pass kids. It may look nicer if you run two smaller passes at a lower heat than running one large pass at higher heat. Just a thought.'Mike
Reply:SandyI guess that's why they say "timing is everything". I'll work on that.Jolly RogerBug holes? Are you referring to undercut, or the bubbles that sometimes come up in the middle of the weld. If the later, I assume that is from trying to fill to much in one pass?I'll try welding uphill. Not sure about the technique you describe, maybe it will be clear on monday.Engloid I don't know if what you describe will give me a large enough weld in one pass, but I'll give it a shot.ironman715I'm going to stick with single pass on this. You may be right when it comes to looks. and strength but I don't really need absolute highest strength on this. If this was something more critical than a fence than I would definitely use two passes.Thanks all, I appreciate the help!
Reply:Well, it looks like I fixed my undercut (thanks Sandy!) But I definitely have more fine tuning to do.I tried welding uphill and It didn't go well, burn thru (the rest of the posts were SS20) and even more undercut. I didn't have the time to work it out so I finished them horizontal and rolling.I'm definitely going to have to learn how to weld uphill and downhill.I spend so much time welding gates with .065 tubing that I haven't learned the other basics.Thanks all! Attached Images