sheet metal MIG

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If I'm not worrying about warping, is it reasonable to run a bead on 20ga, maybe a butt weld, without burning through after a couple inches? Running C25 and .025 wire, trying to figure out if it's my technique/settings or just not really possible.Lincoln 175HD
Reply:Do any of the machines in your signatures have continuous voltage control or are they all tapped machines?  If they are tapped that may be part of your problem.  the heat will also make the seams want to pull apart.   Are you tack welding first?Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Yes, one of them has continuous voltage control (the Craftsman). Even with it, I end up burning through if I try to do a decent length weld without stitching it. I can TIG a long stretch without burning through, but that's a different story than MIG. Yes, I'm tacking first. However, even if I'm just trying to lay a bead across a continuous sheet, I'll end up burning a hole at some point.If it isn't reasonable to do a continuous weld on 20ga, I'll stop trying. If it is reasonable, I'll keep practicing.Lincoln 175HD
Reply:Fit-up is important. Should be no gap between pieces for metal that thin. Can you clamp the pieces to your table or to a thick strip of metal to act as a heat sink?Also, try a "whipping" (forward and back) motion with the gun, or make a series of short beads, almost large tacks, with a short cooling period in between. Should be doable with practice.Edit: what you call stitching is pretty much what I described. May be necessary on thin metal, just make sure your starts are not too cold to fuse with the previous weld.JohnLast edited by Silicon-based; 11-05-2012 at 07:59 PM.Reason: New infoA few weldersA lot of hammersA whole lot of C-clamps
Reply:Most of how I learned to weld was in a community college course, on fairly thick material. Most of it was stick, at that. We were never MIG welding on anything that we had to worry about burning through on. For the purposes we were taking it, it was a great class - and the instructor was kind enough to let me show up to other sections for practice - but we did very little on thin stuff. He was kind enough to let me practice on whatever I wanted to, but the MIGs were all set up with .035 or bigger - fairly different from .023-.025 wire.Lincoln 175HD
Reply:Can you do a lap weld or do you have to do an edge weld.  A back up copper heat sink might help but pretty expensive.  Stich welding might be better where you move along the weld starting and stopping,basically as series of tacks.
Reply:I'd like to learn how to do everything I can. Most of the time I'm sure I could get away with a lap weld but it's nice to be able to do a butt weld when I need to. Running straight CO2 it's damn cheap to weld, on C25 it's a bit more but not too bad. Mostly I just don't want to practice something if it isn't really possible.Lincoln 175HD
Reply:Its possible but u probably need to speed up as the metal heats up.   I would check with your past instructor and see if u can pring your machine in and get a bit of coaching...  the machine itself will make more of a difference on the thin stuff too.  2 different brand migs can feel like 2 different processes running the same settings.Just thought of 1 thing, you are pushing and not dragging the torch right?Last edited by soutthpaw; 11-05-2012 at 09:11 PM.Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:I was mostly taught pulling but I tried pushing and was still having issues with burn through.Lincoln 175HD
Reply:How long of a bead are you trying to run on the 20 ga. without burning through?-Pat
Reply:Currently, I can get something like 1-1.5" before I burn through. Would be nice to be able to run double that, but if it isn't possible anyway I won't keep trying.Lincoln 175HD
Reply:Originally Posted by slotardCurrently, I can get something like 1-1.5" before I burn through. Would be nice to be able to run double that, but if it isn't possible anyway I won't keep trying.
Reply:Originally Posted by dave powelsonReversing the MIG polarity-from 'normal' will impart less heat.
Reply:Normally gas shielded is run DCEP, self shielded DCEN. I was under the impression that EN puts more heat into the base metal than EP. In fact, when I picked up the MIG I'm playing around with on Sunday, it was set up all wrong: the roller was wrong, the tip was wrong, and the polarity was wrong. I tried welding with it before checking those, and (on the 20ga sheet metal I was using) I was getting cold looking welds and burn-through at the same time - so I don't think changing the polarity would help.Lincoln 175HD
Reply:Originally Posted by soutthpawDo any of the machines in your signatures have continuous voltage control or are they all tapped machines?  If they are tapped that may be part of your problem.  the heat will also make the seams want to pull apart.   Are you tack welding first?
Reply:I gotta ask are you using any type of weave? Trying to run a stringer? Nobody else has really asked much about technique.
Reply:practice is generally a good thing but throwing out a major, real-world variable like warpage means that what you are doing now is wasting time, wire and gas.Practice means that ALL the real world variables are IN PLAY and you weld and keep welding for months and years until the result catches up with your expectations.I think what you are doing now is wasting time.
Reply:Originally Posted by slotardIf I'm not worrying about warping, is it reasonable to run a bead on 20ga, maybe a butt weld, without burning through after a couple inches? Running C25 and .025 wire, trying to figure out if it's my technique/settings or just not really possible.
Reply:Originally Posted by Jimmy_poppractice is generally a good thing but throwing out a major, real-world variable like warpage means that what you are doing now is wasting time, wire and gas.Practice means that ALL the real world variables are IN PLAY and you weld and keep welding for months and years until the result catches up with your expectations.I think what you are doing now is wasting time.
Reply:Originally Posted by DanI don't understand why you think the unit having a variable voltage dial or tapped selection would make a difference. Set up with an.023 wire and C25, my Migmaster 250 and Ironman 230 both dial down to a gentle arc that allows you to run a couple plus inch long weld beads on a tight fitting butt joint constructed out of 20 ga.Most tapped and variable units are able to be dial down to around 25 - 30 amp on the low end. Keeping this in mind, the more important factor in how successful a unit is going to be at performing the task being discussed is the type of low end arc characteristics the unit produces. Due to the design of the choke and also slope, some unit produce a softer gentler low end than others.
Reply:Originally Posted by Mikel_24You mean setting the wiring as if he was going to use Flux Core Wire instead of solid wire?I have heard that changing polarity when stick welding does have this effect, but never heard about doing it when wire welding!Are you sure this is going to work? Legit question, no kidding.Mikel
Reply:If the comment disregarding distortion was to specify focus on the burn through, ok. But as other posters stated, all parameters affect the end result quality.I asked the same during the short welding portion of the basic auto body VOTEC class I took: one of the widely accepted practices is usually making short welds or stitches on thin sheet. We did a rust-out patch on a fender; the patch was a lap fit up and we just skipped around the clock face tacking. I did the same for the 1" .0625 stainless tube for the handle on my mig cart, because I'm not so good at it yet.Its just the way it is, so if you get good 1" or so welds, don't try to re-invent the wheel.Last edited by jtcnj; 11-10-2012 at 10:56 AM.Lincoln AC/DC 225/125 and WP17. 75A AC is for pipe thawing!HH 140 - new addtion 9/2012.I didn't agree, but hoped for Hope and Change.I got change for myself and my family: for the worse.This is the reality of: Barackalypse Now. Again.
Reply:I think the way I would approach this is mark the seam at every 1 inch. Weld an inch then move to another area.  Since you can't get longer than 3 inches, just weld an inch and backstep until done.If it is a low stress joint, then ESAB Easygrind wire is a godsend. Burns soft and clean on C25 gas.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.