I will never butt weld sheet metal again

I also have done body work for a long time . Butt welding with a torch for me was the hardest thing I have ever done. You watch guys like David Gardner (Mindover on HAMB) and he makes it look so fricken easy to do it without filler rod and it just flows together seamlessly. When I do it the only thing that flows is frustration bordering on tears. I started gas welding a lower door panel with the torch and ended up making a new one and Butt Mig welded that one. The nicest thing about gas welding or tigging without rod is you don't have to spend all the rest of the day "GRINDING""
I also have an old Lincoln 200 and have 35 wire on it.Had it since 1977.
You know all these guys say you can't lap weld a panel and have it last with a flange are full of it. If you are worried about moisture seal the back with Duraglass. I like to butt weld because it is easier to stretch the weld and HAZ...PRACTICE>PRACTICE<PRACTICE
Gerry

 

1 dont butt weld panels on the car until you know how to butt weld !!!!!!!!!!!! 2 use the correct size tip with a neutral flame that is as big a flame as you can get from the tip NOT A BIG TIP WITH THE FLAME TURNED DOWN 3 spend some time welding strips of panel steel together learning WHAT HAPPENS TO STEEL WHEN HEATED IE IT EXPANDS then and only then work on the car !!!!!!! my trade teacher taught me 30 plus years ago how to do this even puddle welding up side down on floor pans sorry for the rant but it takes time to learn butt welding with a torch thats why people are called tradesmen

 

I did a body trade and butt weld, takes more time setting up however the results speak for themselves. Use just enough heat to fuse the surfaces together and not put too much heat into panel. Horses for courses.

 

Lots of insults getting thrown about here.
Why are you guys getting so personal?

 

I hate to break your heart here, But the reason you think it is a waste of time, And the reason you blew holes through your seam Is "You did not know what you were doing" It is that simple....I do not mean this in a bad way, But it is what it is!.....I guess it all comes down to what you want to have when you are done, I mean if laping metal on top of each other and letting the overheating suck the seam in, and then globbing bondo over it is good enough for you, Then No need in taking the time and doing it right. But don't try and tell people on here that taking the time to do a job right is a waste of time. Also If you were using the right size wire and had your settings correct on the welder, making holes should not have happened. My advice would be to find someone to learn from on how to finish metal, If you do that you will look at bodywork a whole New way, It is amazing what can be done with the right knowledge and practice.

 

Thats exactly how i do it too

 

Hey, greating from the rust belt.

The right metode is a question of car, where on the car, price, skills and tools!

If I work on POS OT DD and rusted out shit, I do lap MAG weld. I keep an eye on the HAZ and take my time.
Our cars has to get MOT every 2 years. So work has to be up to spec.
So I go out of my way to make it look like it's Factory made. Keep my grinding to minimum, under the car I only grind on razer edges, and rod sticking thru.

When it comes to old/vintage cars I break out the TIG ( heli-arc?), and do some nice butt welds, but mostly in places where I have access to the backside.

In the bottom of a vintage car, I dont have any issus with lap welds if: 1) It looks right 2) it makes the body more rigid.

In my book it's more important with small HAZ and after treatment ( Oil, paint etc.).

I know an old body guy that swears to laps, fiberglass Bondo and a steady surply of Oil on the back side after paint. Thats for DD abd stuff like that.

MAG Butt Welds in 1mm will always be a PITA.
Just my 2 cents.

 

trying anything new is usually very time consuming until you get the hang of it. This reminds me of the post about "they" saying it can't be done. Just because someone trys and can't do it doesn't mean it can't be done. I learned that a long time ago. Lots of things I was told can't be done I have done. It may have taken lots of trial and error, but once I figured it out and practiced it could be done and was a better way.

 

You just made that word up! "Craftsmanly"..... I LIKE it!

For the record, I AM to butt welding what a black hole is to space. I've tried to blame it on everything from dirty metal to a bad ground to shitty wire. Turns out its me! I'll keep trying. So far its a skill I DONT have in my bag.

 

Here's what i do. I leave a gap and you have to learn to put the filler in the center. I make as many tacks as need and weld roughly 2 inch sections. If you don't tack properly then this would never work and you will have to start all over! This makes the metal pull up which you can use a shrinking disc to get it flat again. Or instead of using the disc i keep a cloth in some water and shrink it back down after i weld it. Rarely does it shrink down to where i have to hammer/dolly it back out. But i have been doing it this way for some time. I tig weld all my panels in and use silcon bronze filler since it has a lower melting point than er70s6 (normal steel filler wire).

Either way it's practice practice practice.

 

Perhaps a rethink is in order here.
In a lap weld, even if the panels are homogeneous, it is over twice the thickness no matter how you look at it. Lap with no flange is 2x metal thickness with a step on both sides, lap with flange has a double deep step( bead) on the back but flush on the front and is 2x metal thickness. That bead adds a considerable amount of rigidity to the panel .

 

That is mostly because of the acid flux/leading process used over these factory seams......
I cut out leaded seams on almost every top chop I do and 99 percent of the seams are rusted under the leaded seam=even the fusion welded machine done seams like on the rear roof pillars back in the day.
a properly fitted and welded lap seam,treated on the back by painting and undercoating will last every bit as long as a butt seam.
Of course I only have 45 years of experience so maybe I should listen to the younger set who seem to be much more knowledgable....

personally I do most panel work as butt for ease of installing a small peice in a roof corner for instance.
on some I do a small lap if fitting is better by using that type on a large panel....
then if you want to one can slice thru with a .045 cut off and [pull it up flush as welded] ending up a butt seam.
cleanup of the rear of this type seaming is a must tho so it will have to be accessable on the back......

 

I can't speak to your process as I haven't done it personally, but typically in MIG the gap would promote the porcupine effect of the welding wire on the inside.

Additionally, using no gap is largely for consistency. Any weld causes shrinking, and in the case of a low crown panel, there is typically insufficient shape in the panel to resist any of this movement. So in a case like welding horizontally through the center of a quarter panel (adding a repair panel at the bottom) any shrinking tends to pull from the adjacent panels, losing some of the crown in the process. It's here especially why the "Leave a gap" theory causes so much headache. As the heat causes the shrink, if someone did leave a gap, there is nothing to keep the panels from moving even that much more closer to one another. The first tack weld will pull the panels closer together, the next even more. (weld on either side of butt weld clamps and you'll see quickly how much the panel moves). Now when you planish to stretch the weld and HAZ, you'll also have that panel movement (and inconsistent movement) to try and compensate for, making the task more work. So if you did leave a gap, that becomes a larger hurdle in trying to restore the panel's crown. An absolutely tight butt joint between the two panels (or to the best of one's ability) is crucial to keep the panels from pulling together, losing even more crown/panel shape. This consistency even starts with fitting up the panel. Tight joints in some areas and wider gaps in others will result in more welding and thus heat in those wider gaps, for more shrinking, more planishing required. As for using the gap to allow for weld penetration, IMO the welder should be properly set up with adequate heat for full weld penetration (without a gap), and with sufficient wire feed speed to not blow holes. This should be done first on scraps before welding on your car/project. Consistency throughout the process, from panel fitment to welding methods to planishing, will make for better consistency in the results.

 

i had a damn fool argue with me about patches. he overlaps and just tack welds them evey inch .

says new cars are just held together with spotwelds so whats the diff?


ok good luck with that .

butt weld is the way to go and weld it soild

 

.023 wire with gas.
butt weld with a small gap using the panel clamps.
gas weld with coat hangers (strip the coating) as they are soft and are easy to hammer weld.
Flanges on factory cars has a weldable primer/paint between them and thus don't rust.
If you are flange welding use a weldable primer.
Welded flanges tend not to warp as much due to the double thickness.
But when they do warp they are a PITA to straighten.
If you look though some of the threads on here regarding panel repairs or modifications they are all butt welded.....

weld on ............

 

Plus the fact that if you have to put any filler over your seam, with the different rate of expansion and contraction you will get stress cracks in the filler and the paint on top of it

 

I'm having a good laugh at this post...
Almost the whole pecking order of "Patch panel superiority" is represented.
Doesn't anyone grasp that ALL this is bull and that the methods mentioned are all viable depending on situation, access and post repair rust protection?

Sure butt welding is the only way to go for invisible repairs. Thats obvious.
IF its done right and thats VERY difficult...especially with a MIG.
How many butt welded panels actually get finished on BOTH sides though?
Without proper finishing on both sides the butt joint is just as likely to rust as a lap joint and has the potential for cold lap spots allowing moisture to seep thru anyway!
You gotta have skill and practice to do it right and make a totally moisture tight joint.

Lap joints using weld thru primers and proper sealing/rust protection from behind can actually IMPROVE a novices chances of doing a good looking and long lasting job.
Still requires the right prep though.
It's not as frankenstein as slapping a jagged piece of tin 3 times the size of the hole over untrimmed rust and welding away!
If a sloppy job like that IS your plan...you're doing it wrong anyway and really ARE an idiot with no sense.

I'd hate to see ONE CAR left in the garage because some guy didn't have the skill to butt weld. Thats just silly!
Ultimately its none of our business anyway.

If we have a job here at all its to suggest the very best ways and still be willing to accept that sometimes a bit less than perfect is as much as we are gonna see.

My name is Bill...and I've lap welded.

 

I repair power plant gas and steam turbine parts, and yes, the pulse feature is used for regulating heat, I use it all the time. But it only works well when laying a continuous bead not dot or spot welding. For small spots I just feather the pedal and add a lot of post flow Argon to control heat and cool the weld. I don't know how well it would work welding continuous beads on 18 gauge panels, maybe someone on here has done it.

 

Hi Bill.

 

I Bill,I'm Redline and I have had lapdances....wait....wrong forum....hahaha...

 

I'm not about to jump in the lap/don't lap debate, but if there is one thing I've learned during my years welding its that no matter how much I disagree with another man's welding or fabrication technique if it works for them and it gets them the results they are looking for then let them do it. It only makes them mad to suggest another way.
There are many ways to skin that cat, you can bet that he's gonna hate every one!

 

Interesting thread ,but there did seem to be a lot of roosters in the pen.

 

i understand the philosophy of you professional guys, you have a sound reason for pushing butt welding, gas welding, etc over anything else because you've had years of experience in working with it. most of us out here aren't professionals by any means; we make do with what we can afford and on what time we can spare. same way with paint; i've seen dozens of threads on how amateurs should leave paint to people who know what they're doing...
and you're losing sight of why we come here and post our questions and observations; we need input, positive input on how to do things, not a steady round of name calling and insults. i'm still welding with a 110v flux core buzzbox and that's all i can afford or even want to invest, so i have to do a lot of grinding and hammer work; that's the trade off for me.
i have to poor-john my way through every job i do; no money for luxuries.

 

I agree ...I use .024" wire and 75/25 mix, a block of graphite or copper can be used as a backer for the tough spots or wide gaps

 

Just because you failed to do a proper butt weld, does NOT make it a waste of time, or only do-able for professionals. That is ignorant thinking.
If you have been schooled in the body shop methods of working, you have to change your tune , if you want to do quality work.
Seems like you also need to get a dose of patience, and practice more. A quality procedure like this needs you to be more attentive to what you are doing, especially in fit up, and setting up your machine, like others have said. Do more research on how to set up a panel for a butt weld, and working your MIG.
Sorry, but I cannot understand how any sort of good training would lead you to believe that using 035 wire on a MIG is god for sheet metal (Sorry MP&C...I dont' know how you even do it, seeing the quality of your work!). Lap weld are for used car dealer work, and floor pans.
I do all 3 types of welding in my shop, gas, TIG and MIG, all have their correct applications. While butt welding does take a bit longer to prep, in time you'll get faster with fit up and more accurate in your welding technique.
To do ANY of these welding styles correctly, it takes proper instruction, practice, and experience before you become good at it. You seem to be thinking that just one or 2 sessions will maek you proficient. Practice more, and be diligent in setting up your machine (with 023 wire, as well!) and watching the wled process as you do it. Correct your mistakes, and learn as you go.
MIG is easy...try gas welding thin sheet metal, if you want a real challenge! But once you get it, it gets easy, as lots of the good craftment on this board who gas weld, will tell you!

 

I understand the metal workers on how they see things, but it's not a good reason for some of the comments on here. I am a carpenter , cabinet maker and it just drives me up the wall to watch some body beat the crap out of wood trying to build some thing . Then it looks like crap ,but they don't see it or care. As much as it bothers me I would never tell them they don't know what they are doing.

 

This has been a very informative and timely topic for me, as within the last week two friends have told me I need to widen my fenders by a couple of inches (wheels in photo are mock up). I have tig and mig but little experience in light gauge/auto body work. So in the spirit of demonstrating how to do things properly, and out of the kindness of my heart, I am offering up my heap for someone who wants to tackle the job and document for the good of the forum.

 

One of the best sheetmetal welders I've ever seen is a guy I was raised around in south Texas named Leroy Greek.

He welds with a torch and then hammers the seams. I'm not exaggerating when I say that you can run your hands over his finished welds and you can't feel them. I don't think I ever saw the guy use any filler.

I'd LOVE to sit down and learn from the man but he lives 7 hours away.

My dad passed down my grandfather's torch set to me, so my equipment investment would be nill.

I guess I may be over-glamourizing torch welding, but to me it seems like a real craftsman way to go about welding in patch panels, etc.

 

Well put , Chopolds . Practice makes perfect .
I work with fabbing/welding sheetmetal nearly everyday , especially during the winter (our "off-season" - I restore British sportscars) , and I have used many different techniques to weld panels together , and each have their benefits . I do leadwork over all of our repairs , so even a stepflange/spotweld seam is sealed up (even with spotwelds every 1/4 inch , you can see the lead sealing it up on the backside) , and a bare minimum of filler is needed . Butt welding is definately not the easiest way to do it , but when you get it right , it's pretty cool to not see the repair once finished (if that makes sense ) . I've been at it 20 years daily & I've never seen our work fail . We also treat hidden areas with Wax-Oyl once the car is done - that helps preserve them too .
I guess my point is that whatever way you can do the job , just fixing the rust is a step forward , and if that way is to lap weld , so be it - but don't bash other ways of doing it because you failed at doing it . Just practice .

 

I'm a newbie (3 builds deep), and have only done minor sheet metal work (shaved handles, tail light swaps, nosing/decking, minor rust repair, etc)... But I never even considered that you could lap weld a panel on the exterior of the vehicle. It seems to me that a lap weld would leave you with a ridge on the panel that would require filler to even out, and I try to use as little filler as possible. If you were to flange the panels to even it out, then you've just lost any time you would have saved over a butt weld by making the flange.