sheet metal welding woes

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Tricks, techniques and photos re: sheet metal welding?  I recently upgraded to a MM212 mig since replacing body panels in my last project and I have been practicing to improve my technique for my next american muscle car build. Set at the lowest settings the 212 gives similar results as my old mm135. Basically my process has always been to alternate tack weld while cooling with a wet rag and or using a brass backing plate so as to prevent warping, a tedious venture and with a concern for the starting switch on my machines. I've attempted and can maintain a contentious bead on sheet metal but I feel it generates too much heat & distortion for my purpose. I have the same concern when attempting to weld this thin stuff using my lincoln 275 sq wave tig.  I've been practicing lap & butt welds w/ .032 thickness scrap which depending on the source you use, is ether 20 gauge according to engineersedge's reference, or 22ish gauge by weldingweb's? (see links below)  Most reproduction panels seem to be listed as 20 gauge by suppliers.http://weldingweb.com/vbb/showthread.php?t=2941http://www.engineersedge.com/gauge.htmLast edited by badknot; 02-11-2012 at 02:20 AM."Steel is weak. What is steel compared to the hand that wields it?"- James Earl Jonesmiller 225 w/ 3035spoolmate, Lincoln sq wv 275 w/radiator, hypertherm 600 plasma cutter, other stuff
Reply:I'm sure most us knows someone that knows someone that can weld bubble gum wrappers, not say'n it can't be done, nor am I from Missouri but...show me!  What I got so far and I'm not so proud of it so I'll go ahead and say it for ya'll ..."good thing it gets covered up w/ filler and paint."  I'm just a hobby welder, jack of all trades...master of none.  2'' pieces of .032" intermittent dab bead using what I have on hand, .030 wire, 023 would have probably helped. Though thy bead is not so beauteous, it's narrow heat signature signals to me little to no distortion.  It was cool enough to handle w/ bare hands momentarily after welding which could possibly save under coating in certain situations or the time involved to remove / replace that stuff.  I threw in a piece of 1/8" just to show I can manage a bead. It was the only piece i had on hand and I stopped a couple o times to adjust settings but didn't get were I liked it because again, I'm a hobby welder and I have to relearn what I forgot by the time the next project comes along.  Once I do get it dialed in though, I can mig beads that look very similar to tig on 1/8''+ Attached Images"Steel is weak. What is steel compared to the hand that wields it?"- James Earl Jonesmiller 225 w/ 3035spoolmate, Lincoln sq wv 275 w/radiator, hypertherm 600 plasma cutter, other stuff
Reply:Start keeping a journal with the settings you arrive at for specific applications. Why reinvent the wheel each time you pick up a torch?Nice muscle car BTW, Z28 or Firebird?I was a Mopar guy back in the day so I can't figure it out from what I see of the tail lights.JoeMiller Syncrowave 200Mac/Miller MW130 MIGKalamazoo bandsawCincinnati Arrow 500 VMCColchester Dominion 15 x 36 lathe with 2 axis DRO
Reply:Try welding with smaller "tacks", and scatter them at diferrent ends letting them AIR cool and using a copper/aluminum heat sink will help. Keep "tack" welding off of previous welds. You'r not going to get nice beatifull mig welds on sheetmetal. Also sheetmetal should be "butt" welded as much as possible not "lap" welded to prevent rust and your fit up should be allmost perfect( when thereis a gap there is more space to shrink) this causes the dreaded warpage.. Hope this help's.....Lincoln pro mig 180Lincoln Square Wave Tig 300/wp 20/home built water cooler Victor, Purox, Harris, O/A welding/cutting setupsVintage Craftsman drill pressVintage Craftsman/Atlas 12"x 36'' lathe7''x 12'' w/c band saw Everlast 140 st
Reply:Originally Posted by scudzukiStart keeping a journal with the settings you arrive at for specific applications. Why reinvent the wheel each time you pick up a torch?Nice muscle car BTW, Z28 or Firebird?I was a Mopar guy back in the day so I can't figure it out from what I see of the tail lights.Joe
Reply:Originally Posted by scudzukiStart keeping a journal with the settings you arrive at for specific applications. Why reinvent the wheel each time you pick up a torch?Nice muscle car BTW, Z28 or Firebird?I was a Mopar guy back in the day so I can't figure it out from what I see of the tail lights.Joe
Reply:"Try welding with smaller "tacks", and scatter them at diferrent ends letting them AIR cool and using a copper/aluminum heat sink will help. Keep "tack" welding off of previous welds."  That's how we've always done things but being relatively new to this forum and seeing amazing work done by others, I just thought someone out there might possibly have an innovative technique. been practicing butt welds also though lap welds are often unavoidable when replacing these skins so we painstakingly apply undercoating in every nook and cranny, got five years in this build, no rust yet. btw, it's actually a 67' rs ss camaro, they only did the vent windows on the 67's.  we ended up replacing 90 percent of the sheet metal, only the dash and the panel behind the rear seat are original. looked like a decent car when we had it shipped from texas...not so much as it turns out. 383 stroker, TKO 600 five speed, 4whl disk, ac, other stuff.  my pal and i are starting on a 32 ford pick up now...has a much better body for a starting point. Attached Images"Steel is weak. What is steel compared to the hand that wields it?"- James Earl Jonesmiller 225 w/ 3035spoolmate, Lincoln sq wv 275 w/radiator, hypertherm 600 plasma cutter, other stuff
Reply:If you want to get seriuos about welding sheet metal you'r going to have to learn either tig or O/A to make nice welds on sheet metal. There is also SiliBronze; you can use it with all three process'. Use a rust preventative, (weld through primer, and other coatings) to protect from rust, undercaoting works good but will work even better with the use of these other available coatings, even the black "primer" on most of those new panels is an excellent coating so remove as little as possible. You may consider buying the dvd by David Gardiner....Excellent dvd, with LOTS of info...Very nice car by the way.... looks really straight,with nice gaps. (they definitly did NOT come from the factory that way)Last edited by DemonSpeeder; 02-12-2012 at 01:20 AM.Lincoln pro mig 180Lincoln Square Wave Tig 300/wp 20/home built water cooler Victor, Purox, Harris, O/A welding/cutting setupsVintage Craftsman drill pressVintage Craftsman/Atlas 12"x 36'' lathe7''x 12'' w/c band saw Everlast 140 st
Reply:With regards to tig welding sheet metal, I've found that using the least amount of filler possible is the best route to go as far as keeping warping and burn through to a minimum.
Reply:There was a guy with a post on here recently who was a sheet metal master (imo). I cant find the thread but it had a lot of good info. I'll keep looking.www.performancealuminumfabrication.com