First attempt at welding sheet metal

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I made a practice run at welding some 16 ga. sheet metal, photos are below. I'm looking for input from experienced weldors on what I can do better, change, etc. My goal is to build my skills in order to make some floor pan repairs in my Jeep.(Ironically, the metal I welded here was from the housing from an old Miller welder that I found at a scrap metal company.)I cut out about a 3" square piece of metal, ground the paint and burrs off the edges, and clamped it in place with a copper heat sync backing plate.The gap between the pieces was about 1/16" which is probably way too wide.Here I am practicing with .030 flux core wire in a Millermatic 211 but will switch to c25 and solid wire for the Jeep work.I made tack welds in alternating locations to help prevent warping the metal which seemed to work. I did not get any noticeable warping.The last photo is after 2 passses of welding and grinding. Clearly I need to make a 3rd pass to fill the remaining low areas.Other than probably getting a narrow gap between the metal and using solid core wire, what else can I to to improve my welds here?  For this kind of work, can a pro make the repair in one pass? Or is it expected that multiple passes would be necessary, especially to prevent the metal from warping?Last edited by Ken4444; 01-30-2011 at 12:34 PM.Milermatic 211
Reply:Just more time at it- Fluxcore is beech on think stock Might as well get the Solid wire and gas now and start practicing with it.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 have seen much worse for a first time..Like Ed stated thin sheet is no fun at all with 'core..Seat time is your friend..(I just happen to have another Miller side sheet if you need it )...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by Broccoli1Just more time at it- Fluxcore is beech on think stock Might as well get the Solid wire and gas now and start practicing with it.
Reply:agreed:  gas for body work lots cleaner weldsand i would take more paint off around the weld area clean clean helpsidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:i've been playing with my new mig for the past week or so. using the flux wire to weld on 1/8" thick tubing. bought a c25 tank and put some solid wire in the machine. so much easier to control.filling gaps with fluxcore was a pain in the ***.
Reply:Ken, put a stringer down about 4" long with out a joint. Take a picture and post it.
Reply:Hey Ken,I'll see if I can enlighten you a bit regarding sheetmetal & allow you to get a grasp doing this thin metal, especially auto panels. Ok, I do 4-6 classic/show car resto's a year & nothing will take the place of good 'ol 70S-6/.023 w/16cfh of C25.1) prop-doctor is correct regarding removing more paint around the joint.....at least 1/2" minimum.2) Definitely do some practice pieces to set up your MIG as far as heat/wf. & a backing strip is a must. I use some 1/8" alum & copper depending on metal configuration. The copper is easy to bend for corners & radii.3) You need to increase your gun angle(45-60*) to flatten the puddle as this will reduce/eliminate burnthru.4) NO GAP.... tight seam or slight overlap will increase success ratio. I do a lap joint on all the car resto's.....much stronger & the panels are generally undercoated or painted or covered if in the interior.5) SAVE THE FLUX-CORE FOR A GARDEN/FARM TRACTOR REPAIR!Here are some pics of 18ga(.050) flat seam weld & 16ga(.062) rect. tube I did with the above parameters. Gonna need (2) posts to get the pics on so give me a couple xtra minutes. Hope this will help you have a better understanding with sheetmetal. Oh, BTW, I do have an advantage on you as I have been doing this over 40yrs, although I still setup every job with a couple scrap pieces to be sure settings are optimum.Denny Attached ImagesComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:2nd Group:Don't hesitate to ask any ?????.Denny Attached ImagesComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:Originally Posted by yorkiepap2nd Group:Don't hesitate to ask any ?????.Denny
Reply:great show an tell  Yorkie  after the grind down,hit the weld with the DA and pime an paintidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Hey SEAR,Yes, I ran (2) separate beads & cooled with a wet cloth right after welding. I had a "senior moment" & forgot to mention to keep a wet towel handy for the auto sheetmetal welds. And, definitely keep the beads 1" or less & keep varying seam area locations. I ran 2.5" beads in the pics as it was on the welding table. Good question.... keep 'em coming.DennyAddendum: I wanted to emphasize that your beads will come out superb if you are good at maintaining wire stickout(I like 3/8") & travel speed. Consistency with your application will produce the best welds.Last edited by yorkiepap; 01-30-2011 at 02:15 PM.Complete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:In my area you can rent tanks by the month or the year or do lifetime leases on larger ones, can still buy small tanks. I would check into that if you don't want to jump on it right away. Sometimes I will go in and pick up an extra tank if I am doing a big tig project and am burning through argon like crazy. half the time they won't charge for the rent just the contents so usually that is the first tank I burn up that way I use all the gas I paid for rather then take back a half full tank later.Millermatic 252Lincoln 175 plusTA 185tswTA 161stlhypertherm pmax 45Victor torchHenrob torchAn S10 for each day of the week
Reply:Originally Posted by HuckxcKen, put a stringer down about 4" long with out a joint. Take a picture and post it.
Reply:Originally Posted by yorkiepap4) NO GAP.... tight seam or slight overlap will increase success ratio. I do a lap joint on all the car resto's.....much stronger & the panels are generally undercoated or painted or covered if in the interior.
Reply:Thanks everyone for the suggestions. Clearly I need to ditch the flux core and get going with the shielding gas. I will pick up a bottle this week. As one person (or more) said, it's almost pointless to keep practicing with the flux core.Practicing on the same metal (still with flux core), I did a lap joint. It tacked in fine, but I went back and welded the seams and that looked like crap There was no point in grinding it, so I didn'tAnyhow, thanks again for all of the suggestions!  I'm looking forward to moving to solid core wire.Milermatic 211
Reply:I'll agree with the others that the .023 solid is the best way to go but lacking the set up it can be done with flux core. Lot more effort but it can be done. After reading your post I went an played with this a bit this afternoon. The first pic is the metal clamped up with that same copper backing you had. Notice the NO gap. remember this. It'll show up again later.Second pic is a row of circular spots about the size of a pencil eraser, maybe bigger. Third pic is the same spots cleaned up. Fourth pic is what it looks like flipped over. Attached Images"The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Next I did a row of circular spots on the back side but this time made the spots closer and overlapping.First and second pic show the row of spot welds on the bottom/back side.Third pic here shows it flipped back over to the top side and shows that more spots might be needed if it got ground down to flush. I didn't take it that far tho. Not great but doable. This was .035 flux core BTW. Attached Images"The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Now to the gap. Just be carefull with not leaving a gap under all scenarios. I took these only to show how much shrinkage can have an effect. Hard to tell in these pics but with no gap these two edges were actually in the process of trying to climp over or under each other and I believe actually contributed to the amount of warpage a whole lot. So if ou don't leave a gap, be sure to tack the ends or perimeter then proceed with the spot welds and/or filling in. Attached Images"The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:I have bought my tanks on craigslist, $100 for a 57 scf full of 75/25, $45 for an empty 40 scf.You'll notice a big difference on your MM211 by switching to gas.BillMillermatic 2111960 Ford Ranchero1975 Dodge B200
Reply:Okay, I picked up a 125 cu ft bottle of c25 this morning, loaded some solid core wire in the machine, put on a new tip, and all I can say is wow!Everyone was totally right: Solid wire with c25 is night and day different from flux core.Here are some photos and commentary. Here's the welding cart and gas cylinder:With my son doing the design work (he's 7), I practiced on some 3/16" and 1/8" scrap. Wow!  The welds are far superior to the flux core ones, and as good as the ones I did in my 1 day welding class...Now, on to the sheet metal. I put some test beads on the same scrap as before. Here's a comparison. Huge difference:I tacked in a small piece. Even the tack welds look much improved. Clearly the fit-up isn't perfect so the gaps are too wide:I took the risk of running some longer beads in a couple of spots, and did get some burn through. I went back and made more spot welds and then filled in the 2 holes I had made:Here's the piece after one pass of welding and grinding. With flux core, it took me 3 passes of welding and grinding to even get close to this:I'm still unsure about doing a lap joint vs. a butt joint when I do the actual floor pan repairs, but I"m confident that I can turn out a much nicer (and probably stonger) repair job now, especially with more practice.Milermatic 211
Reply:Originally Posted by SandyNow to the gap. Just be carefull with not leaving a gap under all scenarios...
Reply:Rather than fit the patch to the original, you may find it easier to make your patch, then cut the original to fit the patch. This way you can use the patch as a template to mark where you need to cut, then cut the original smaller than the patch and then trim for an exact fit. This still works with a lap joint, just make the hole smaller and skip the fitting part. Eastwoods sells a visegrip like tool that creates a flange or step in body pannels for doing lap joints that lets you stay close to the original surface height..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:If you cut your piece of old metal out in one piece, you should be able to use it as a pattern for your new piece.  Just allow for the width of the cutoff wheel + whatever extra if you're wanting a lap.  Cut it a little big if you'd like, then take the edges back a little at a time with an angle or bench grinder.  It's a pretty fast process on thin metal.
Reply:Ah, ya got me by one minute, DSW!  Two opposite approaches to do the same thing.What wire size are you using?---preferably .023/.025Switch your 211 to 120 volts for less heat input on sheet stock.(I use a 211--among other things.)Blackbird
Reply:Originally Posted by Ken4444Here's the piece after one pass of welding and grinding. With flux core, it took me 3 passes of welding and grinding to even get close to this:.
Reply:Originally Posted by A/C GuyYou are not moving at a consistent speed, the weld varies in thickness. The lower left corner, especially, shows lack of penetration with gaps in the weld. Also, wood is a good insulator, that makes the metal that you are welding stay hotter longer and will cause burn through. Get a piece of 1/4" plate to put on that wood work station, that will help pull the heat out of the material that you are welding. That will slow the process slightly and help you as you practice and learn.
Reply:You dont even have to waste wire if you disengage the drive rollers.
Reply:Originally Posted by metalmeltrYou dont even have to waste wire if you disengage the drive rollers.
Reply:That .023 wire is about 8000 inches per pound. You can waste a few inches before you've lost a penny. "The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:ken, thanks for posting this you do good work you can tell and im glad i didnt have to dig his thread up from the grave,i justtried my first attempt for the same reason floor pans and i can tell i work dirty hah, also im doing flux. hf 90ampi noticed i like the wire speed up where as ive heard a low feed was better, i want to get as much material down as fast as possible, so i was wondering if i might even turn up the amps too (high) Along the lines of how Sandy i think is using .035 wire i heard it burns less hot which is not making sense to me now, basically playing with wire speed and size.anyone have any good tips for using flux on sheet besides not to? i am outside and i care about structure more than looks as it wont be seen. thanks