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Welding Sheet metal

Discussion in 'The Hokey Ass Message Board' started by jhnarial, Nov 13, 2009.

  1. jhnarial
    Joined: Mar 18, 2007
    Posts: 410

    jhnarial
    Member
    from MISSOURI

    I am curious, how do you weld your panels? What is your method and why?
     
  2. onlychevrolets
    Joined: Jan 23, 2006
    Posts: 2,307

    onlychevrolets
    Member

    MIG....controlled heat is why.
     
  3. jhnarial
    Joined: Mar 18, 2007
    Posts: 410

    jhnarial
    Member
    from MISSOURI

    But what is your method?

    How do you actually weld the panel in? That is what I want to know. I do also want to know mig,tig,or gas welding.
     
  4. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 8,224

    theHIGHLANDER
    Member

    Mig and tig here. Tig prefered but mig works too. I use ESAB 'EG' (easy grind) for smoother finish work, and I try to have a helper hammering the spots as we go to avoid the weld shrinkage pulling the panel. I've not torch welded sheetmetal in decades. Some love it, but all 3 methods are OK.
     



  5. You mention ESAB "EG" wire..are you referrering to MIG wire...if so were can you get this...
     
  6. onlychevrolets
    Joined: Jan 23, 2006
    Posts: 2,307

    onlychevrolets
    Member

    a bunch of small welds...and jump around, sometimes a dolly and hammer if needed. Every panel has its own need.
     
  7. jhnarial
    Joined: Mar 18, 2007
    Posts: 410

    jhnarial
    Member
    from MISSOURI

    I'm getting ready to go to work but what I am really looking for is how do you avoid your panels from getting distorted from welding?

    Do you cool your weld,do a little at a time,hammer your weld(if so how?) or any other means you might have.

    I'm looking forward to reading this when I get home.If you can do a small picture tutorial to help others see how you do it,That would be great.This could be helpful to all of us.

    Take care
     
  8. jhnarial
    Joined: Mar 18, 2007
    Posts: 410

    jhnarial
    Member
    from MISSOURI

    Good point,Lets just keep it in general.Lets just say a panel you have complete access to.
     
  9. motobilt
    Joined: Oct 4, 2007
    Posts: 112

    motobilt
    Member
    from okc

    we use tig and mig, the esab EZ grind wire is the best for sheetmetal, you can get it at any well stocked supplier, IWTS here in Oklahoma City keeps it in stock for me, so if you cant find it, give them a call, (405) 942-4987, I use .025 size and it works great, and the difference in grinding is huge! Price is about twice as high as normal carbon wire, but is well worth it
     
  10. onlychevrolets
    Joined: Jan 23, 2006
    Posts: 2,307

    onlychevrolets
    Member

    the biggest part is to make sure that panel is where it needs to be. ie: straight and not higher or lower than the panel it's being welded to. Then tack and check, tack some more and check again, like highlander said hammer when needed. it's not a race and if one weld takes an hour so be it...take your time crappy works looks like crappy work.
     
  11. jhnarial
    Joined: Mar 18, 2007
    Posts: 410

    jhnarial
    Member
    from MISSOURI

    When you say hammer can you explain that a little more.How is a weld hammered?
     
  12. onlychevrolets
    Joined: Jan 23, 2006
    Posts: 2,307

    onlychevrolets
    Member

    with a dolly on the back side...hit it while its hot!!!
     
  13. DMFB
    Joined: May 22, 2009
    Posts: 545

    DMFB
    Member

    What he said. It is real easy to burn through that thin stuff.....and even easier to start warping it.I do a series of overlapping tacks about an inch or so long....cool it with an air hose, and go on. That is after it is tacked in place of course. That method works for me.
     
  14. chad
    Joined: Jun 22, 2004
    Posts: 1,012

    chad
    Member

    I mig and tig...Alot of the time I just mig....I tack the panel about one inch apart make sure the fit is nice and tight..Sometimes I put a small chamfer with a file on the pieces...But..I find the key is a really nice fit up....Spend the time to get it right the first time...Like I said tack it about 1'' apart making sure again the the panels stay inline,,Once its tacked I will go back over and knock the tacks down until they are almost flush with the edge of a 1/16 zip cut. Give them a few taps with a slaper to stretch them back out.Then I will go back over and start welding from the center out...Just short tacks that over lap each other until I have the 1'' section filled in.%Then break out the old trusty handy dandy 1/16 zip cut again,knock it down until its almost flush and give'r few taps with the hammer to stretch it back out Keep on going until its welded..I should add that .I never weld more than 1'' before working the same area...As soon as I am done the 1'' weld I grind it and stretch it back out.
    Then if your really fussy you can break out the shrinking disk to take care of any spots you over stretched and then you can finish with 80 grit on the DA sander...You can almost perfectly metal finish like this...I know their are a few people that can....I cant take credit for this way of doing it. I learned from another member on a another board who is a master metal shaper...But this way of doing it really helps you keep it under control.I learned alot form doing it this way..Giver a go you will be surprised!!...

    I tig pretty much the same way I just don't knock the weld down the zip cut...
     
    Last edited: Nov 13, 2009
  15. chop&drop
    Joined: Oct 11, 2006
    Posts: 455

    chop&drop
    Member

    Tight butt joint, gas weld with 00 Victor tip and a minimum of filler metal (1/16" copper coated mild steel rod), hammerweld with body hammer and dolly of the correct configuration for the panel. Short welds, moving around to keep heat distortion down. Provides smooth, malleable welds and will require very little grinding.
     
  16. buckeye_01
    Joined: Jun 20, 2005
    Posts: 1,441

    buckeye_01
    Member

    Mig here too. Measure the panel just short and use small tacks all over. Be patient and allow them to fully cool. Don't try to speed the cooling process with water or compressed air either, you are asking for big problems then.
     
  17. John_Kelly
    Joined: Feb 19, 2003
    Posts: 535

    John_Kelly
    Member

    Johnny is testing us : ) Gas welding. Tack every 1" or so, weld the whole thing up, hammer and dolly to stretch, bump up low spots, smooth with hammer and dolly, shrink to tune up, repeat, and done. I have no worries about warpage, just do whatever I have to to get the surface back where it was. Don't care if the metal pulls, shrinks, is over-stretched etc. Easy fixes all.

    John www.ghiaspecialties.com
     
  18. carcrazyjohn
    Joined: Apr 16, 2008
    Posts: 4,844

    carcrazyjohn
    Member
    from trevose pa

    Mig here too.I just jump around and take my time,Butt weld ......Patch panels I flange
     
  19. oj
    Joined: Jul 27, 2008
    Posts: 6,257

    oj
    Member

    I spend a lot of time in metal prep, the side i am welding and the backside as well. I backup the seam up with brass shim stock and scrap aluminum to both seal the weld area from oxygen and to absorb heat, this spreads the heat so that (with a tig) you can jack up the heat and have better control. The heat is highly concentrated at the seam and the backing pulls the heat away so that if you get distortion isn't focused or pinched. I do a tack about every 3/4", i used to start in the middle and work both ways but i am not sure this is necessary with steel, sheet aluminum will move around at lot so starting in the middle mades a difference. I make these tacks high, i just leave a nice dot of steel and work the dots with hammer and dolly, 3 wrist taps with a martin 168G. Now i break everything down and check the backside for contamination, and clean again. While i do the tack welds i keep hitting it with a stainless steel toothbrush. To finish weld i rebuild the backside, the brass will have warped and has burn-thru's so you need new stock. The actual welding begins at a tack and goes to the right 1/2 distance to the next tack and then to the left of the tack the same distance, i spread the metal left at the tack in both direction so that the heat goes evenly out from the tack as the tack is now the firmest point if you go only one direction away from the tack the heat will go in that direction gaining in intensity when you go to the next tack and the panel will roll in that direction. I generally do a couple tacks (about an inch and a half) and then hammer/dolly the weld. The weld now should have little 'proud' because you are moving the puddle, i use AllState 275 filler (I weld chromemoly and prefer this rod, its' really too expensive to use it on sheetmetal panels and there is better rod but i just like the color). I skip around to keep the heat from concentrating and take a break after a pass. I check the panels to see if i need to do extra hammer and dolley work and constantly clean everything. The area i have problens is when i start joining the individual short welds together, i get distortion at the leading edge of the 'haz' (the blue heat area) of the current weld and the lagging edge of the existing weld. It will generally form a 'Y' with the panel raised. That can be bothersome to work out.
    Like all welders, i don't always do it like this and am always experimenting but if i am welding on a roof or something that people will really be able to see i use the above procedure.
    I just looked at a '29 caddy in a friends shop for restoration, it was in another shop where work was started. They had to weld the rear corners of the roof, it looked like somebody glued to of those crooked cigars to the metal, you couldn't cover those welds with a shingle. Just a goddamn crime that a noble a car as that could make thru all these years and have some hack do something like that. Made me sick.
     
  20. So I take it that some like to fit the patch tight? I've read in the past about leaving a 1/16" gap, and those small clips are that size, so what's the general consensus?

    I've heard of the easy grind for a while, and it is logical that less heat while grinding is a good thing, but then warpage is inevitable, so?
     
  21. metalman
    Joined: Dec 30, 2006
    Posts: 3,284

    metalman
    Member

    Personally I NEVER mig weld sheet metal. Never have tried ez grind but I have too much trouble with the weld breaking as I hammer, weld is too hard. Maybe ez grind is a softer bead? For years I gas welded till I bought a tig, use it 98% of the time, the 2% is when I run out of gas at 7pm!
    My method, same with tig or gas: Always butt weld, can't do much about warpage with a lap weld. Good fit is important, I like my gap no bigger then a .035 cut-off wheel leaves. No overlaps, no wide gaps. Clean metal is important too, I like clean shiny metal on both sides, Contamanated welds will leave pinholes, ect. Tack every inch, leveling with a hammer & dollie as I go. I use a slighty crowned hammer on dolly, with a few taps you see your gap close to near nothing between the tacks. I go back welding between 2 tacks (1" at a time), followed with hammer on dolly the weld while its hot. The idea is to flatten the weld and strech the shrinkage back out. No heavy hammering, you don't want it streched too far. No water, you don't want to shrink back in what you just streched back out. If it cools too much before you get it flat, heat it again. Skip an inch and do the next inch. When your'e at the end go back and do the skipped areas. If the metal is thick enough (Old Fords) you won't need much filler rod if any. Even on thin metal I use very little filler rod, usally with the tig I use pieces of .035 wire stolen out of my mig. The more filler rod you use the more metal you have to grind off, no fun. The idea is too add just enough filler to replace whats missing (gap) and no more. Beware of going too fast and heating the metal too far out from your seam, you don't want to start oil canning 6" away, especially with gas welding. I weld bare handed, if I can't rest my hand on the tin while I weld I wait till I can.
    After it's all welded up I knock the weld down flush with a 1/8" cutoff wheel, being carefull not to cut into the base metal. Do both sides if you can reach it. With little filler rod this doesn't take long at all. A little pick and file work after that and your done. Done right you'll not be able to see your seam at all.
    Sorry if this is too winded but I spent 4 hours yesterday hammerwelding a 49 Oldsmobile rear fender together I'm sectioning (5/6' long!) so the process been on my mind. Late 40's/ 50's GM sheetmetal sucks to weld (thin and hard) but the fender came out nice, won't need any filler because of the welding.
     
  22. pitman
    Joined: May 14, 2006
    Posts: 5,079

    pitman

    Amen bro! Like he said. ;)
     
  23. hasty
    Joined: Jul 5, 2009
    Posts: 1,410

    hasty
    Member

    Very helpful thread - thank you.
     
  24. oj
    Joined: Jul 27, 2008
    Posts: 6,257

    oj
    Member


    Nope, no gaps. Metal needs to butt tight, oxygen coming in from backside thru a gap contaminates the weld. Never have figure out how people use those gizmos, panel clamps? i think they are called. Maybe with mig you can use them but i bet you'd get just a ton of warpage.
    I have a question, how do you guys prevent 'pinch' at the weld seam. I have this happen from time to time and don't have a handle on what it is. I assume it is shrinkage of some sort but it has different character, it has a very short area with tight defined radius.
     
  25. Minimal gaps- I try to achieve no gap, but will accept a gap that isn't much bigger than the MIG wire (I use a Lincoln 140 MIG with .025 EZ grind and Argon-CO2 mix).

    That said, I used panel clamps when chopping my tudor (do a search for the thread- there are LOTS of pictures). They're great for aligning big cumbersome panels. Obviously, the gap can't be any tighter than their thickness :(

    On my first attempts at patch panels, the weld seam would sink below the surrounding sheetmetal. I later learned that it shrank more at the surface- thus pulling the top together more than the back-side and creating a very shallow V.

    The way I overcame this was to do a set of tacks on the front side of the piece, then do the next set of tacks on the back side. This, along with some hammer-on-dolly work, kept the seams flat. Obviously, this only works on panels where you have access to the back side.

    Hope this helps!
     
  26. I remember an article in Rodder's Digest where they showed a rod shop welding on the back side of a panel with a mig that had been modified with an air nozzle attached to it. You would apply the tack to the back side of the panel and open up the air nozzle to immediately cool the tack. The air was supposed to quickly cool the heat affected zone to prevent it from spreading out too much and by doing your welding on the back side of the panel that wouldn't be seen, you didn't have to grind as much weld bead, off leaving as much bead as possible for strength. Anyone ever used this method? I currently don't have a mig of my own but will be picking one up within the next year. I haven't done any sheetmetal welding since I read this story so I never got the chance to try it out. Does the application of cooling air do anything to the structural integrity of the weld? Brittleness?
    Also is the EZ grind wire supposed to be softer for hammering out shrinkage or is it just softer for grinding? Mig welds are much harder than other types of weld.
     
  27. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 8,224

    theHIGHLANDER
    Member

    I've found the EZ grind doesn't crack as easily as the good ol regular wire. The trick with mig/hammer welding is 2 guys on the job. Someone needs to hammer and dolly the tack 'just right' to stretch the weld. The tack should look like the head of a nail when it's hit just enough. If you can do this every tack along most of the weld the metal finishing part nearly does itself with a light grind and few occaisional pick n file moves. With tig, if you get the temp just right and keep a near zero gap, moving from one spot to another as much as the weld allows, you can get away with no hammering and a nice metal finish with light easy grinding. Now all of this relates to early sheetmetal which is heavier than the average 'asian' patch panel.
     
  28. Gas with a Henrob. 1/16" gap, 1/16" mild rod. Tack every three inches or so with gas or MIG. Hammer all tacks (grind if I use the MIG) Gas weld an inch or so, hammer on dolly while hot. Cool with air. Correct any misalignment as I go. Repeat. I'll never go back to MIG for sheet metal.
     
  29. Nicholson
    Joined: Aug 9, 2006
    Posts: 169

    Nicholson


    Same for me, oxy-acetylene with Henrob or small Victor. Anywhere from zero gap to no larger than 1/16" with 1/16" rod. Hammer and dolly as you go. I have tried several manufacturers welding rods and now use RG-45 from KT Industries. Very clean welds with no slag problems.
     
  30. jhnarial
    Joined: Mar 18, 2007
    Posts: 410

    jhnarial
    Member
    from MISSOURI


    Not a test I just thought it might be a helpful topic.I was actually looking to learn something for myself.

    I like starting threads like this because,usually some good information will come out of them.After reading the replies I can say there has been some really good information put into this thread.


    I would wright how I weld but it has already been written for me.I weld my panels just like Chad explained in post 14.

    I was taught wrong and I just couldn't understand how I could have this perfect patch panel and then just have it destroyed after welding it in.It use to piss me off.

    Then one day I found a thread I think it was called (mig welding thin sheet metal) it was by Randy Ferguson.I only had a mig welder at the time so I followed his instructions and my results blew me away. I just didn't know how to do it correctly until I read that thread.

    I'm getting decent with tig welding now so I,m not doing much mig welding sheet metal any more. Now I want to learn how to gas weld.

    I hope we can still keep this thread going maybe we can do some picture tutorials,it might help some of the H.A.M.B members that have questions.For me it is easier to follow pictures then words.
     

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