i use .030 flux core on my lincoln 135.I butt weld close as i can, tack every few inches,, till filled (let cool alot) then go over it with my grinder, fill areas i missed, grinder again, use little filler... works for me start of a section job on passenger fender new section fitted tacked in place all welded and ground no filler on yet just primered to cover up, but looks good and wont take much filler
I should add ,,that you use the cut off wheel on its edge and do not hold it flat like a grinding disk...So all you do is just touch the high spot on the weld not any of the surrounding metal....You do not want to make the metal thin...I dont use a lot of pressure just enough to keep the disk on the center of the weld...
I have some of those from Lawson that work great for removing welding bead inside of pipe using a long neck grinder. They are safer to use.
The reason I use a cut-off wheel to knock down the weld is you can see exactly how much your taking off, something that's hard to do with a disk. Plus if your metal is slightly off side to side you can grind it flush with the low side without cutting into the high side if that makes sense by turning it the same direction as the weld, makes leveling with the hammer/ dolly easier. Not the best pic but maybe you can see on this deck lid the weld area is smooth and I haven't touched (removed) any metal to speak of outside of maybe a 1/4" of the seam. The slightly off side to side was really evident here because I was welding 18 ga. new metal skin I rolled to pieces of the original skin which is 20/21 ga. If you want lots of practice hammer welding sheet metal chop and section a 49 Olds 98! I feel like I've welded several miles on this car. Lucky for me (I'm getting lazy in my old age) the owner is a bodyman and will finish it up from here, will not be metal finished as he has no problem having a small amount of filler in his car. Could be metal finished but that would be a lot of time ($$$), not worth it to him.
Here is a question I'd like to get an answer to. I've seen guys MIG weld panels every 1-2 inches vs. a FULL length TIG bead. The MIG gets a 6-8 inch wide gob of plastic trowled over it and finally painted. How long will the MIG job last before cracking?
I'll make the panel and leave it bigger than I want it. Use a flexible tape pattern to mark the panel and trim. I don't leave a gap, I'll but that sucker up so you can't shine a flashlight behind it. Then I'll use my MIG to tack it in...grind down my tack welds so it's just proud a little. I'll do that about every 2-3 inches or so. Once all my tacks are ground down I'll go use my TIG to finsish weld it in. I use a little filler rod to create material that I will then remove later. Try to move around the panel when welding like you would when you torque down cylinder heads. This will minimize panel warpage. Use a test piece to set your TIG... you want the smallest heat affected zone possible. Once you get it welded in grind down your TIG welds again leaving it just a little proud. When you heat metal and then it cools it will shrink. You will need to take a hammer and dolly and slightly stretch the weld. The TIG weld is a lot softer then the MIG. I should add that when TIG welding the panel you want to go right over your tack welds to soften them a little. Carefully file down your weld and you won't have to use much body filler if any. The better you get a fitting your panel the better your results. If your fit is air tight you won't have to really use any filler rod but it helps to add a slight about of metal in order to remove it when dressing it up later. Clear as mud? Andy L. Kaempfer St. Louis, MO
Great thread, I am going to buy some sheet metal and start practicing before I start on my car been a while since I have done much welding. I have some floor pans to install in my 48
How do I determine the guage of the body sheet metal and floor pan sheet metal of my 1948 Olds Thanks in advance
Thanks for this thread Johnny, I've picked up some good tips. I'm just learning TIG so I have a lot practice to do before I weld anything important. What do you guys use to grind your Tungsten tip? Do you have a dedicated grind wheel for this? And if so, what grit of wheel. Thanks in advance.
I guess the thing that bothered me about MIG welded is the lack of control. Gas and TIG welding allows you to control the weld puddle, MIG just forces wire out, and seeing both pieces of metal is tough even with a light changing helmet.
I use a small 6" bench grinder (cheapy) with a medium (80 grit?) wheel. They (the welding shop that sold me my tig) say it should be dedicated to the point of breaking off the contamanated part of the tungston before you grind it as to not transfer steel or aluminum to the grinder. A long time pro welder told me it's not nessasary and grinds his with whatever is handy so don't know. Another guy I know uses his belt sander that he sands anything on. My grinder is dedicated but I don't worry to much about breaking the tungston off unless it's real nasty, I have no issues.
Really? I have always used compressed air to cool the welds as I moved around the panel. The problems with warping I have had has come from grinding. How does the air affect it in an adverse manner? Im curious.
Cooling with compressed air doesn't make a difference. When metal cools, metal shrinks. That's just physics. If you use something to cool it you just speed up the process. They only thing that could comprimise your weld is contaminates. That could come from anywhere, your filler rod, the material itself, etc. The material you are welding should be clean and dry. Be real careful when using any chemical solvents here. Sometimes if the substrate is very porous it could collect and when vaporized by the heat you can create very toxic gases that could make you sick or kill you. I've heard of people using brake cleaner in this manner and dying from this. Just grind the metal till it's bright and go slow. The bigger the heat affect zone the more shrink that will occur and therefore more warpage. Andy L. Kaempfer St. Louis, MO
The faster you quench the weld bead, the harder it is going to be. This is part of the reason why TIG and Oxy beads are easier to grind and planish than MIG beads, even when using the same filler. The MIG spots quench a lot faster, so they end up being noticeably harder.
Tig for sheet metal, no gap, ER70s2 .035" rod, hammerweld after each weld, don't quench at all, ever!!! It's not rocket science, metal is stupid. Save the Mig for your chassis stuff, tractor, p.o.s, etc. Only use on sheetmetal for positioning (tacking) if you have to. I only use it when I desperately need to. Usually, I gas weld aluminum sheet only, if I do it for steel, it's only to blend in with the rest of the welds on a hand built vehicle I'm restoring. Judges usually frown on new-age repairs. I don't care for the heat input it gererates. Oh yeah, keep practicing tig every day, it gets easier everytime.
You bring up a good point. There was a thread on here a while back (the HAMBer's name escapes me) that the author almost died and is having all kinds of health issues. As I recall, he had no idea that this could happen until he was hospitalized. Try googling brake clean welding or brake clean phosgene and read up. Scary stuff to say the least. I'll get off my soapbox now. Sorry for hijacking your thread Johnny.
Really good input Andy. If you think by cooling the weld with air or water is helping control the heat,does your weld still have a blued area surrounding it?
I just re-read this thread and was just getting ready to say that we have covered everything.Then I noticed we do not have a good tutorial on gas welding. If some one could do a good picture tutorial on gas welding we could call this thread done.I can not help with this,so hopefully someone will volunteer. I had fun with this thread. I do not have anything else to add so I'm signing out. I'll will see you guys on the board.
I mig weld my sheet metal, take your time and stitch weld it, I usually do either an 1 inch or 1/2 inch apart welds, grind them and start filling in more, don't run a contuinous bead or you'll warp the shit out of it.
I MIG welded this fender and fender well using the same procedure. You can not hammer on a MIG weld very much before it will crack.So fit up is crucial.If your fit up is good it will only take a few light taps to re-stretch your haz as you go along.I have only cracked one weld but I blame that on a poor fit up on my part.I was asking way to much out of that weld.
This was mentioned earlier, never hurts to spin it again... http://www.jalopyjournal.com/forum/showthread.php?t=382835
I can mig steel ok but when it comes to sheet metal I suck. I am of the understanding that when mig welding, a gap in the two pieces should be of equal thickness to the filler rod. However, there seems to be some disagreement in this tread (if I read correctly), It is my understanding that the filler needs "to go somewhere"...again, I am referring only to mig. Without a gap, the filler will distort the sheets..yes/no? I have some luck using a torch with no gap and no filler, just got to practice to reduce distortion.
Thanks for this thread guys. It's nice to know that I'm not the only one out there still doing sheet metal with my mig. I was taught in the same manner as Randy's tutorial about twenty years ago, and have always had pleasing results. Most of my friends have gone to TIG these days, and all I hear is how much better it is. I wil eventually spring for a TIG machine, but I've never experienced the problems with warping, cracking, and shinking that I keep hearing about. I will be looking for the esab easy grind wire, and I will try filing a small bevel on the edges, both sound like great ideas.sloorider, I think alot of what you are questioning as far as gap can be better controled with wire speed. I adjust by sound to get the slowest wire speed I can get, and still get good penetration. This leaves a very compact spot weld that goes all the way through, yet doesn't build too high on the surface of the weld. The filler doesn't really need "some where to go", you just don't need to use too much of it. I use gaps as close as I can make them. I do still use gas welding for aluminum sheet, but I'm not great at that yet.
what diameter MIG wire works best for 18-gauge sheetmetal? I used .35 on my roof (if I remember correctly) but .24 on my hood. My hood warped more than my roof and I was going to stick with the .35 but then I read somewhere that there was a good reason to use the smaller wire for 18 guage steel. I'm confused and need opinions from those more experienced with sheetmetal welding.
I remember reading something from one of the known tin bashers who said that he spent roughly one hour per foot of metal finished welded seam. I'm slower than that.
Next week I may be able to put somthing together for you Johnny. I'm doing another '36 fender from scratch and I am gas welding it. I would do it sooner but I Just picked up another lathe and have some rearanging to do this weekend. Everybody needs 3 lathes in there hobby shop right? Jeff Edit: I forgot to tell you thanks for another good thread Johnny!!!
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