Technical Welding on patch panels

Gluing panels with a lap joint will result in the same problems as welding one in that manner and if you are planning to paint the joint will eventually map through the finish and be noticeable. Panels on modern cars are glued along flanged edges not lapped joints along exposed panels. The two layers of material will expand and contract at a different rate to the surrounding panel which is what will cause the joint to be seen through the paint.

If you do decide to use panel adhesive all have glass microspheres in them to retain enough glue material between the panels. If you start to hear a popping sound (like rice crispies in milk) when you are clamping you are applying too much pressure and breaking the spheres and pushing out too much adhesive.

 

Thanks. Its all mig welded.

 

K13, by flanged edges are you talking about using a step tool instead of just laying two panel edges over each other?

 

Oh, well that explains a lot.

People who weld over rust deserve what they get.

 

It seems like guys are split on whether to finish the butt welds with gas or TIG. I've only done gas on sheetmetal, and I've hammer-welded butted panels, but have never hammer-welded with a TIG.

I want to buy a TIG to do the panel welds, but I'm not sure about the process of hammer-welding with TIG. Frankly I was just looking forward to a TIG torch that shuts off when you release the trigger, rather than an acetylene torch that's still going when you set it down to hammer. That & maybe less warpage & shrinkage.

But the TIG weld will cool faster right? So I'll need to do shorter skip welds or hammer faster or both? I'm counting on TIG requiring less hammering & filing too, but maybe I'm all wet on this one.

 

You'll be about the same, not sure that you'll notice less hammering but the gas welded panels get annealed in the HAZ so they seem to move easier. You can set up a scratch start tig without a pedal for pretty cheap. You can also get a nifty little torch hanger. Is has a spring loaded hager that stops the gas flow to the torch and puts it out, but there's a standing pilot on the hanger. So you just pick the torch up and light it off the pilot, never need to touch the knobs or tune the flame its exactly as you set it down.

Both of those are much cheaper than a tig machine with all the bells and whistles if you want to up your game without too much commitment.

 

Thanks 31Vicky...I think I need one of those.
But what I really want is a shiny new toy with bells and whistles galore.

The thing is, I've only spent a very little time in a pro body shop, mainly sanding & painting & bumping out dings. It was back in the 70's as well, and it wasn't like Boyd's. It was more like a big barn with a paint booth and a giant WW-II surplus air compressor; so I'm not familiar with the best practices nor new stuff in the modern shop either.

My impression is that TIG would give far superior results & require less finishing. I'd pay the $$$ for that perk.

But maybe I'm better off with a torch for everything. It's what I know best. I was planning a couple grand for the TIG.

 

Looking at those pics ,I believe that stuff is overlapped temporary, those zip screws act like clecos and hold everything in place so you can trim and eventually butt weld those pannels together ... That would sure be a mess if everything overlapped!

 

Kind of like this yeah?
I use clecos while the panel is off and on, then I put rivets in the holes for welding and trimming.

Man I don't know with the caulk line and flanging pliers, they are at it with the zip screw holes and rust. Maybe we can hope they at least trimmed the ragged edge I wouldn't have paid one pinch of goat shit for that job.

 

if all you do is overlaps or flanged welds you will never get any better. your projects will always require more mud than they would otherwise. if your goal is to get the project at hand done and you have no desire to improve your skills and do things right then overlap welds are perfect for you.

 

Flange pliers were used. That overlap is permanent. What a wreck.

 

Butt weld only for me. I learned to do it that way from the start but I mig most of mine.

 

No what I mean is modern cars have dedicated flanges designed into the panel for glueing and entire panels are glued on like a quarter. If a panel does run into another panel, say a quarter into a b pillar, they are never glued together at that seem they are butt welded. Automotive adhesives are wonderful things but they are not really designed to do patch panels on old cars. Yes you could create a step in one panel and glue the other panel to it but that seam will always show up through the paint at some point down the road.

 

[ butt join my stuff and it sounds like most guys here do. my question is doesnt anyone use lead instead of mud any more.

 

Lead only on customer request. Modern body fillers are faster an cheaper.

 

I didn't check your links... the pics were fuzzy..I guess he did overlap. Poor model A ... The stuff he made didnt look to bad... I wonder why the short cut ? He's a pro tho :-/

 

Professional, and "gets paid to" are worlds apart.

 

I have to ask why?? If you've got a welder then why not use it? For those who don't own a welder....if you want to do body work or anything else handy, it's a solid investment. It's not like you are going to glue your chassis together just 'coz you don't have a welder, then it's the same for body work too. Just because they use it on new cars doesn't make it best practice.

I bought a welder about a year ago because I want to do some body work on my pickup, practice as much as I need to before I will tackle doing the actual work. As stated by many, butt welding is the only way. If MIG is all you have then lots of tacks, spaced out to prevent warpage - like ebfabman's post. This can require a skim of bondo to get a perfect finish. Difficult to hammer and dolly MIG because of the hardness of the weld.

If you want to see a great example of patch panel perfection, check this thread from the The Metal Surgeon http://www.jalopyjournal.com/forum/threads/32-sedan-lakester-roof-chop.934219/page-6 You can see with the roof insert, it is tacked with a MIG, welds ground down, and then filled in with TIG and hammered, filed, hammered and filed some more until prefect.


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There is a misconception that a $500 and $5000 jobs are different, yes quality does cost more usually but not always. You don't have to pay a fortune to get a quality job what ever it is, you just have to find the right guy. Many shy away from folks who dont charge what they think work should be, it's too cheap, his work must be lousy, I have seen both, high $$$ and low $$$ work that's sub par.


Doing a butt or flange weld/repair, they both need to be trimmed and fit, abit more time for a much better final product, no brainer. Some times you have to do a lap weld/repair to match the factory look, usually spot welded, we all know how they survive time in wet climates, even with seam sealer.

 

I don't. No shop that I have ever worked in did, and not a single one that I know of does. Not a single one that I have ever heard of does.

Post a list of names. Prove it.

 

What about welding from the backside of the panel if you can?

 

I'd be real careful with the use of the word "any", especially when you're implying that some of the folks on this forum are not well-known or experienced. You've been on this forum four months now, you should know better.

 

Well, the person in question is a "noted pro".

Yup, noted as: do not hire.

 

we butt weld everything

 

glue them together, has anyone tried this??? I would like to on my next junker.

 

"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."


Sure like to know what respected shop(s) you're referring to....I butt weld only, no lap or glued panels.

 

that's me, I just want to get the dang thing done and drive it. I guess I'm in the minority here.

 

I takes just a few more hours to do it properly.

 

these posts are always the same. I'm still waiting to see a glued on patch panel. I would rate glue as one step below brazing. may as well use duct tape.

 

I guess my definition of "properly" is different....I only expect it to last the life of the car. And so far, mine have.