Question welding sheet metal.

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Having just bought my first welder the other day (Lincoln Handy Mig) I went down to the scrap yard and picked up a variety of metal to practice with. I found a bed frame that I cut apart then welded back together, some thick grill grates, some thin grill body metal (really thin sheet metal that makes up the sides that surround the bottom propane tank area of a grill)Welding on the thicker metal doesn't seem to be an issue as I can get the "bead" or molten area of metal to move around and work well. It's the thin metal that I'm having an issue with. I'm just blowing holes in the metal when I'm trying to join two pieces. I have the welder set on it's lowest settings, but that doesn't seem to matter.I'm using flux core wire, so I'm curious if I went to a thinner non-flux wire and a shielding gas, if that would help? I have a truck roof rack that is somewhat thin that I'm getting ready to weld on and I don't want to ruin it!
Reply:I'd clean the metal better and did you clean the back side before you welded? Using solid wire with shielding instead of Flux usually goes better on sheet metal. But you can use the flux. Also bed frames are made of cheap spring steel they don't weld great.
Reply:Yup- the .035 Fluxcore is gonna give ya problems on thin sheet metal.Pick up a small bottle of shielding gas and use the .25 solid wire that came with the machine.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:I just did a project for a motorcycle on 18 gauge sheet, with some 11 gauge bits in there too... used the 0.35" innershield that came with the welder (lincoln 210mp). I had it bright and shiny clean, and settings to about 60 inches per minute on the wire speed, and about 15.5 volts. it worked good, gotta move the puddle along quick though.
Reply:mr.dgold - I did clean both sides, but maybe not well enough?I was suspecting a smaller size wire would help with the sheet metal. I'm also thinking the metal is almost too thin to be welded and I'd be better braising something this small. I'm just trying my hand at any kind of steel I can get my hands on!Thanks for all of the advice!
Reply:Trying to weld sheetmetal with fluxcore is like putting socks on a chicken. You can get it done, but it's going to a struggle and the results won't be pretty. Get yourself some .024 wire and a tank of C25, you'll be glad you did
Reply:For thin stuff, one technique to try (besides the suggestions I gave previously on the gas and the wire) is to dial back the wirefeed and the crackle, and instead get away from short-arc to a quieter semi-globular transfer that is almost like slowly tossing little wet balls of liquid steel into the joint. Takes a while to get the combination, but once there you can slowly carry a bead vertical-up on a sheetmetal butt weld with a gap almost the size of the wire. Also be aware that where burn-through is an issue, a lot of guys will trigger on-off bursts, letting the joint dissipate heat for a second or two. Be sure to always have the torch held close to the joint even during the "off" parts of the sequence so that maybe there's some shield-gas retained in the area. If you want to try this on-off triggering technique with no-gas flux-core, first get the smallest size, which is .030" (unless there's something new), Hobart is one maker.  With this stuff, try holding the torch different distances form the joint. You might find that you can have the wire hanging way out there while filling holes. Flux-core is smokey and messy, but you certainly can learn to make acceptable welds with it. Our grandfathers' generations managed to make welds that would do the job under a lot worse conditions, with a lot worse materials. Since (as I gather from what's been said) you already have a roll of .035 flux-core, go on and try that on the thicker steel, such as the bed frames. ' As for bed frame steel, the problem is not that it's some low-grade junk, but that it actually is relatively high-carbon, heat-treated to make it strong and springy, which is what's needed for the application. It can crack, so give it some preheat. You'll still screw up the heat-treatment, but it probably won't matter for what you're making (dozens of car battery hold-down frames, in my case). Gas welding it sort of automatically preheats it, and you could consider brazing it. I never miss a chance to pick up a free steel bed frame (in fact with what metal costs anymore, I pretty much scrounge whatever free metal is offered if it looks like it might be useful someday. And the leftover cut-offs and scraps I save get smaller and smaller!!).Last edited by old jupiter; 05-19-2016 at 01:42 AM.
Reply:Sheet metal with flux core, blip it, pull the trigger into it almost burns through, then back off, pull it again as with a pulse.....and repeat. Agreed flux is not the best for sheet,
Reply:I had a neighbor that wanted me to make him a thingymabob with an old bed frame. It was a pain to weld but got it to hold up for what he wanted it for.
Reply:Judging from your picture, you will need to clean the metal better.  Flux core wire will leave a residue - much like stick welding.  You need to make sure that residue doesn't contaminate your bead when using a pulse technique. Solid wire with C25 will give you a much cleaner environment.