Good morning folks. I am knee deep in the bodywork of my 1972 GMC. I've done rocker panel, inner rocker, cab corner, fender lower sections, and kick panels on the passenger side. I am butt welding using mig on that. I am on to the drivers side now. I keep staring up, though, as I have a good bit of additional unknown up there.

When I first embarked on this quest, about 4 years ago, I shaved the drip rail off of the truck (in additional welding the cab seam, which looks great!). A look which I love and intend to keep. I heated the roof too much, and tin-canned it. I tried to fix it, but in my enthusiasm and inexperience (this was before the aforementioned bodywork) I ruined the outer panel and cut it off out of frustration.

Water under the bridge. Let's not bog down discussing -that- further.

I now have a gaping hole on the super-thin outer rook section. The stock thickness is 19 gauge, but it seems thinner than that where they drew the metal to make the curves near the edges of the roof.

I bought the Eastwood "flange and flush rivet and glue your panels" kit and decided to try it out on a the bedside I am working on now. I cut it off after a few hours of messing around and butt welded that panel on. What I learned is that the flanging tool is crap. The flange it makes is messy, not straight, not deep enough, and it's REALLY time consuming and hard to do properly.

I have heard on here that sometimes the adhesive route can result in a visible seam on hot days. This is not the ticket for a roof. Is this true? I really don't think I can weld on it as-is, the heat would be too much, yeah? Am I stuck with welding a strip along the seam underneath? I have an entire top section from a donor, although no A pillars. Please don't tell me to weld it at the pillars and then shave the drip rail again. Please please please.

If you are curious, you can see my crappy bodywork "skills" on my build thread.

http://grassrootsmotorsports.com/forum/ ... 103/page1/

That wandered.

In essence. The thin outer roof panel is gone, there is a hole. I need to attach the patch panel to it. What's the best way?

Thanks!

I saw another try at this, although I'll be adding the flange whereas this person used the factory seams.

http://67-72chevytrucks.com/vboard/show ... 093&page=2

I didn't realize it, but can I just spot weld.flush rivet the flange and then fill it without fully welding the seam?

What is a good flange tool?

Maybe this?

http://www.amazon.com/Astro-Pneumatic-6 ... B007QV7Y5K

How do I handle the seam? Countersunk rivets seemed like a good idea.

Anyone have any ideas about this?

After doing this for a long time, I don't even consider glue, or even flanging. Eastwood sells an 8 pc butt weld clamping set. It aligns the metal perfectly. Once you have the panel cut and its perfectly ready to weld, now your concern is warping the 19 gauge. Sooooo easy to do. Soooo easy to prevent too... Just stitch the panel by welding a 1/4 inch spot, move at least 6 inches away, another 1/4 spot, move around the panel all over to make sure there is no heat transfer. Take your time. Also, if its a large panel, say a rooftop, weld the corners, then halfway between the welds, then halfway between the welds, etc. Done with finesse and slowly, you can butt weld just about everything with the right technique. This means argon mix gas and .23/25 wire fed mig. Tig would be better.

I have this philosophy that works well for me. I don't purposely take shortcuts, use inferior tooling, or ad lib procedures. I do everything the way the professionals do and fail at it several times, asking the proper questions and keep trying until I get it right. Its the hard way, and its a long process, but in the end, its worth it! Right now, its very daunting, learning how to paint, but with these guys in your corner, can't lose!

Deve
www.speedprint.com/Deves50

Dave, thanks for the very helpful reply.

I will have to decide how best to approach this seam, then. The roof panel is big, and the GM quality of the era has the sheet metal stretched tight and thin in some places. I'll go back and find the thickest parts and see what I can find for a perimeter. What's the best way to cut out the patch panel from my donor roof? I imagine to do this properly I need a very precise method.

-Brian

Post some pictures of the roof as it is now, and show where you want to make the seam. Also the donor roof.

Deve wrote:After doing this for a long time, I don't even consider glue, or even flanging. Eastwood sells an 8 pc butt weld clamping set. It aligns the metal perfectly. I have this philosophy that works well for me. I don't purposely take shortcuts, use inferior tooling, or ad lib procedures. Deve
http://www.speedprint.com/Deves50

Eastwood's butt welding clamps provide too wide of a gap. Zero gap with full penetration is the best and correct method unless a repair calls for a mending plate. Their clamp spacers can be changed to thinner ones and the panels notched so they are drawn together for no gap, if one feels the need to use them at all. One should know how to achieve full penetration with zero gap. If not, one does not know how to weld properly. It is not difficult to establish zero gap when mating panels. Eastwood targets the hobbiest's naivity with BS and leads them to believe one needs a gap for proper welding.

Metal shrinks when heated, and a gap causes the metal to be drawn together, causing even more distortion. The HAZ should be stretched after butt welding panels together. Distortion cannot be eliminated, only controlled. You have control over the gap and technique.

Panel adhesive is an exellent product when used properly and for areas for which it is designed.

Hobby and other sites are full of misinformation, heresay, and incorrect data. What one reads should be verified by a professional and other sources. And not all professionals have quality information, nor do all practice professionalism.

Really it all depends on the donor sheet metal. Make the cut smaller at first so that you don't have unwarranted gaps. Use a Makita or equivalent grinder to make the necessary bumps in size, but use the eastwood (or equiv since many companies make these clamps) to start the process on one end. The idea of the clamps is not to get some sort of gap, its to get the panel to fit uniformly. You can also use magnets to hold the panels together if you don't want the very thin, uniform gap for welding. Its not really rocket science as most welders haven't been to rocket science skool, so just do what makes sense to you. Warpage is the enemy. So weld only 1/4" stitches, them move elsewhere, like half the distance to the next corner, etc. Think of a square. Do all 4 corners. then half that distance, half again, etc until all welds are met. Grind carefully too because any heat can cause warpage and the most miserable experience of your life! lol. You can do it. If there is a bow to any of this, use common sense and weld from lowest, to mid, to highest with care. Steel is very funny and unpredictable in the way and ease with which it warps. Any excitation of the atoms in steel makes things happen in totally weird ways. Slow and steady wins the race.

In my experience, you won't like the result at first because it will look really bad. This is why they make Rage Gold. Once the panel is pretty close, spread about an eighth inch coat of Evercoats Rage Gold over the entire panel and sand with 85 grit to rough things out. I am what the other guys call a hobbyist, so pay no attention to what you just read. lol