Technical Welding on patch panels

Question on welding on sheet metal and patch panels

Getting different opinions on this question ??

When welding on a new sheet metal panel I have been told to always weld ( completely) around the panel ,a( continuous) bead .This is to prevent any mosture to get between the new panel and the body itself .That this is done to prevent the welded seam from reappearing through the new paint and bondo in time.Also, a butt weld is better than a overlap Do you agree??

Also is it always a good idea, if it's possible, to put bead sealer on the back side to seal the newly welded area?

Gene

 

Butt weld is Always better.
It should be welded 100% (means without missing spots and full depth) but it doesn't need to be done continuous ( means without stopping)
Anytime you make a metal sandwich you increase the likely hood of some sort of future trouble by 100% in that area. Be it corrosion, showing thru, what ever.
Dressing the back side and applying sealer is a good idea too if it's not going to be finished

 

I agree that you completely weld the seams and that it's best to butt weld panels that are going to be finished and painted.

One thing, don't make one continuous weld start to finish without stopping to let the metal cool or you will end up with some seriously warped metal to repair.

I can show you some spots on my old cab that didn't get welded as well as they should have been nor metal worked as well as they could have been. There is rust now showing through the body filler. That was done 34 years ago when I was a lot shorter on both body work skills and patience to take the time to do things right the first time.

 

I butt weld all my patches and do a full weld. You don't want to do one continuous bead unless you really know what you are doing. Usually I will put a tack every few inches and then I will weld an inch, stop, file the bead and use a hammer and dolly to stretch out an shrinkage.

A lot of people have a hard time doing a proper butt weld so they use a flange and overlap the two pieces. This gives a thicker area to weld on and less chance of a burn through. I have used this method on floors but I don't think this is the best solution for patch panels. If you do use a flange, or anytime there is overlap between two panels, definitely use a weld through primer and seam sealer to keep moisture out from between the overlap. Otherwise you will have rust through.

Thanks,

--louis

 

Fitting a butt weld takes time and patience and practice however it's entirely doable.
The windshield post is not welded yet. It will be tig welded - so the fit up is tight. If it were going to be mig welded I'd have opened it up some. The seams starts at the hinge and travels up at an angle .

 

Although I always butt weld panels, virtually every high quality professional shop to which I am acquainted does a flange (overlap) weld. I won't name names here, but these are major custom hot rod shops, quite respected. They claim that in addition to being quicker it also makes the panel stronger and less prone to warpage.

 

Might fly in California or Arizona....

 

Yes I'll agree its quicker, much quicker.
I'll agree also that it' both makes the panel stronger and less prone to warpage.
Really only logical. But here's what you/they aren't saying about it or are aware of.

The bend of the flange in a area of the panel that's over 2x as thick as the rest of the panel. It not uniform in strength of flexibility and just the heat or the sun will alter the panel at least 2x as much on either side of that flanged joint as it will in the flange. Most folks can spot that shadow thru the paint at 100 feet.

It's not warpage free or warpage eliminating, just more resistant. Being that way it will still warp and what ever it warps to is where it's staying. It's nearly impossible to move any of the metal in the joint no matter how hard you try. Welding shrink metal and you're stuck with it. It needs paved and then shadows thru the filler.

But it is quicker

Everyone is different but I wouldn't put a 50.00 patch under a 5000 paint job.
I wouldn't put 100s of hours of intense labor over a 15 min patch.
If it's a 500.00 scuff and squirt paint job who cares

 

Rebuilding a wasted Model A coupe at a professional shop using flange welds. I'm not necessarily advocating this; I'm just saying that this guy is lots more experienced and well-known than any of us and he essentially built the rear of this A from nothing. If a noted pro does it this way, who am I to argue with the results?

 

I hadn't even thought about how much quicker it would be to not even try to get just 1/2 the rust off the weld joint.


Welding like that gets you a lot of good grinder practice too I'd imagine.

http://www.jalopyjournal.com/forum/attachments/hpim1351-jpg.2746273/

 

Being well-known does not mean that you're good, or experienced.

Always do a surgical-quality cleaning on your metal first, or, at least that's what I was taught, when I started, 36-years ago.

 

The "secret builder" is:

Grey Beards Customs
7215 1st ave. N.
Birmingham Al.
35206
205-836-1227

http://www.ratrodnation.com/forum/rat-rod-builds/'31-model-a-coupetruck-(elcoupamino)/25/

http://www.ratrodnation.com/forum/profile/?u=23;PHPSESSID=ce24e3bb3b4a10e2f95c41e0718d3934

Y'all do know that you can reverse-search images on Google, right, Mr. Permberton?

 

Gympy is 100% correct, butt weld them all the way around, lap joints are bullshit and dont last.Yes, they are quiker to install, but that's about the only advantage - You'll pay for it later i can guarantee you.
I'm only an ametuer home builder myself, but this is what i do and it works -
After both panels are prepped and cleaned, tack them every inch with a mig, then start at the centre and weld between the tacks with a small #6 oxy tip and around 0.40" mild steel filler wire that has been cleaned with emery cloth.
Weld one small inch section at a time, let it cool, dress the weld down to near flush with a cutoff wheel across the top of the weld, then hammer and dolly to stretch in the heat effected zone ONLY until flat (where the blue colour is)
Then move on to the next inch, stop and repeat the above.
Swap over to the opposite side of where you're last weld was laid, nect to the first etc
Once you have completed all you're small sections, hammer and dolly lightly any areas of concern (stretch), then run a shrinking disc over it if you have any areas that need further shrinking. Clean up any remaining welds with a 36 grit sander on a 5" grinder, followed by 80 grit on a DA sander.
I also seal the back of the welds tha wont be seen with a good quality silicon adhesive sealer such as sikaflex, just smear it on thinly with you're finger and wipe away any excess.
Get some scrap and practice as much as you have to before you go ahead and ruin new patch panels.
Good luck

 

Overlapping the joints is a very unprofessional approach to metal repair, and no self respecting "Pro" shop worth their salt is ever going to turn out shit like this. I'm no Ron Covell but I tig all my butt joins with mild steel filler rod and dolly the shrinkage back to normal. Takes some practice but I personally see it as a better option to the mig which leaves a hard weld which is hard to dolly and requires more effort to grind flat, resulting in more heat build up, resulting in more panel warpage.
Just my opinion..


Posted using the Full Custom H.A.M.B. App!

 

um.... "lap joints are bullshit"

Lap joints were used on factory built US made cars from mid/later 1930s to at least the 1970s on certain exposed body surfaces. That is fact.

Why they did this is for practicality and economics, as well as skill levels of average factory workers. Some particular cars in the later years had joints that did fail after a few decades, due to overly deep laps that were prone to trapped solder acid which was caused the inability of the heat to flow the solder into these deeper spotwelded seams. All of these factory laps were spotwelded, not welded solid. In many cases, these deep laps probably would not have failed if modern body filler was used instead of acid based lead.

The whole point of the above paragraph, is to not insist on buttwelds in every case. You go with what the skills allow, where the joint is as far as being able to get to the back side for dollying, the type of welder you have, etc. The worst damage on any car patching, is by a beginner, using a flux mig, along a unsupported panel. By the time the entire weld is done with the heavy added material, then overheated again with grinding, the door is nearly ruined.

My advise is to start buttwelding on the very smallest patches first, and as your skills and tools get better, then go for the more difficult panels.

 

Holy shit....butt weld or not....I'd be pissed if someone dirty ass rust welded my repair like the above pro did. Professional or not, that frekn' guy would be starting over. That's just asinine.

 

The questions one needs to ask...

Will it be driven in adverse conditions again (ie, salt, mud, excessive water)?

Will it sit in the parking lot more than 40hrs a week again, year 'round?

Is it a restoration being done for marque specific/concours competition or notable expos like GNRS?

Can YOU do the work required and do you have good help at your disposal?

Once you've checked off each one then build/weld/fab accordingly. I wouldn't even consider a lap weld on ANY 30s fender for a couple reasons. It has to be finished both sides, a lap weld will tend to permanently change a critical contour, and I'm a snob about quality (as many can sometimes verify). All the warnings of showing later and such are worth considering. Sometimes there's no choice except to lap something, but in most cases it should be to recreate an OEM process. This is where cleaning and joint prep like weld primer should be used. Butt welding is superior and I'm way better with a tig than I am with an O/A torch. Infinite heat adjustments during the whole process seems to be an advantage in my mind, and yes I know there's torches that adjust easily but I don't have/want one. Wire selection is critical too. If the wire is the type for structural use like ER70 S 6-7 it's going to be brittle when done and hard to grind. S-2 has an advantage there for sheet metal work. A MIG can be used to butt weld but again the S 2 wire should be used and in most cases it requires qualified help to be on the ready with a hammer and dolly. The weld should be done 1 spot at a time and be stretched while it's hot. Nearly impossible to do without help if the goal is a top tier repair. You tap the spot as it's cooling to avoid the warp that occurs as it cools without hammering due to the WELD shrinking and pulling the parts together. This is a great way to repair areas that need a big reach inside like 50-60s quarter panels. There's more and you're sure to get it here on this topic as well as many others related. Good luck and keep asking good questions. You can't go wrong if you do.

 

I agree, butt weld is the only way. I was taught this 20 years ago within the first week of Auto body school. If there are any Tech school teachers out there I would like them to chime in. What way do they teach it?

 

another vote for butt weld

 

Just because a pro shop does it doesn't make it ok. Shops are in business to make money and shortcuts are more profitable. That's why there are pro shops that will do a job for $1000 and another shop will charge $5000 for the same job. Boyd Coddington was a pro shop.....and those guys used more body filler on a car than I ever have and they were building 6 figure cars.
I buttweld. Tack with a mig welder then gas weld it up.

 

Here it is done on a OT 67 C10 cab corner

 

I think ole Floyd Cotterpin bought his bondo in 55 gallon drums

 

Hey ebfabman, looks like you just did small tack welds with a TIG, then 'filled in the dots' with more tack welds to reduce warpage along the way? Nice work!

 

Great thread here guys! How about adding a little something into the mix - what do you think about glueing in a patch panel?

Larry

 

Factory panels were spot welded and then lead finished on production lines but if you knew where to look you could see the file marks in the paint. I learned body work from an old guy that was there when they switched over from being blacksmiths and he always butt welded patch panels. He finished with hammer and dolly then lead if needed and finally primer and paint. I stitch weld with MIG then fill in as I go. Dolly the welds when they are still hot and take your time until the entire patch is welded. If you did it right there should be very little finish work required besides grinding down the weld bead and filing any high spots.
It seems to be common practice with pro shops doing high end paint jobs to skin coat the entire car with body filler and spending days block sanding most of it off trying to get a perfect finish to apply paint. That may be OK for trailer queens but I build cars to drive and enjoy. If it gets a rock chip I wait until there are a few more then fix them.

 

"Birdman" Stewart, I think I can safely say is a friend of mine; and, having been lucky enough to hang out with him in his shop while working was like being in church with a faith-healer performing miracles. He butt welded his repairs. Needless to say, only a minimal amount of lead, on rare occasions, was necessary to tweak places his grinding, hammering, sanding and rubbing failed to bring into perfection. I did say 'miracle worker' didn't I? Damn right.

 

My two cents...it all depends on what your aiming for...perfection? Look at flop or schoum's threads and they butt weld, metal finish...absolute perfection..as was stated, 500 or 5000$ paint job, you doing it at home, your self, what's your skill level....all things to consider. Not that I would do it today but the 39 ford Tudor I built when in my teens 40 years ago has pop riveted patches and a skim coat of filler on just about every close to flat surface on the car ( it was sandblasted withHIGH pressure and had war page) and lacquer paint and there are still no cracks...now days I lap weld with a mig and get pretty good results, but I am a perhaps better than average amature,I intend to try to learn butt welding on my next job, don't know if I can do it well or not ...one other thing there are very good auto body adhesives now , I'le bet a low dollar novice could get darn good results cleaning and painting (por 15 or such) and glueing on patches!....hell that's how some of these new cars are assembled! Good luck and enjoy your project!


Posted using the Full Custom H.A.M.B. App!

 

If you can both - fully clamp the surface of the joint , and afford the change of material thickness you'll not have much trouble

 

I am going to try glue. There are soo many products out there note that work great. I was told to use a slow drying glue because a fast dry glue creates more heat that could warp the panel. Would I do it on a high end build probably not. but there's some people that don't own welders out there and this makes it possible for them to do something on their own they otherwise could not. I own a welder and a plasma cutter but I really want to see how well gluing the panels will work. Semis and new cars use it.

 

Another thing with the glue is you don't want to squeeze the panels too tight or you will squish all the glue out from between them and not have a strong bond.