Customs Metal Shapers - Wagon Roof Skin Help.....

We're working on a custom wagon that required welding 2 roof sections together in the middle. I know this isn't for the faint of heart. We have a large oil can area on one side of the weld that won't hold shape. The question is what would be the best direction. Heat shrink the the large oil can area to try and tighten the oil can effect? Or add more shape/ crown with the plannishing hammer to try and get it to hold with more shape? The weld seam is TIG welded and we've began work the weld but don't want to go to far. Ideas?


This is wish the skin popped up.


This is the skin popped down

 

If you had good shape and a tight joint prior to welding then the issue is in the weld seam. The oil can is generally caused by weld shrink not big panel stretch. I say work the weld seam and stay off the large panel. I flush grind my welds on both sides then on dolly the actual seam to push the Oil can back up. It's amazing how it works.
The Wizzard

 

You have major shrinking to do. It can be done. I would use a stud welder/shrink tip if I were doing it.
Start at the outer perimeter and go circular around the oil can working toward the center. Quench with compressed air. This will take some time and the first go round may/probably won' t be enough.
You will be an expert shrinker when finished.

 

Let me ask this. Was the Oil Can there before you started to work the weld seam?
The Wizzard

 

Perhaps direct this question to Hamber MP&C as he is a highly skilled metal shaper that is working on a total rebuild of a 1955 Chevy wagon body. He has a detailed thread on rebuild the wagon body including replacing roof sections. http://www.jalopyjournal.com/forum/threads/55-210-wagon-progress.788490/

If you go to Robert's MP&C thread 55 210 Wagon Progress and click on MP&C Shop Projects at the end of each of his postings that link will take you to his thread on the Garage Journal that has 68 pages on shaping & forming the metal to rebuild the 1955 Chev. It goes into detail on his roof repairs. He also shows in detail how to shrink panels as the Garage journal is a comprehensive detailing on metal shaping as well as the 55 rebuild. I read through Robert's Garage journal posting yesterday and could not stop until I finished it. He details how to shrink a panel with heat and the thread includes Youtube postings with more detail.

Glenn

 

Keep working the welds. If you've just started the metal finishing then it is still shrunk up at the welds so shrinking anything at this point will really screw things up.

Was the oil can the proper shape before welding?

 

I always enjoy Robert's work.

 

Your welding caused the molecules to scramble and spread away from the weld causing pressure around the area resulting in oil can effect. You need to pull the metal around the weld back to where it came from. I start with a torch small tip and a small dime sized cherry red hot spots (not too hot)Don't melt the metal.I use a shrinking hammer and flat dolly under it .Slap around the red spot to draw the metal into the center ( then cool it immediately) with air blower. While you are dolling it slap the hammer back towards the original weld that caused the warp. I also like to use a serrated slap file.You will have to repeat this over and over .Let it cool every time before moving on.Tap around the warped area to hear the tinny sound .as you go it will sound more solid. You will probably have to shrink around the whole area near the original weld. This is hard to ex plane without getting the feel of the metal that needs shrinking. It isn't hard to do just take your time and don't expect quick results. Not everyone will agree with my way but I have saved many oil caned roofs this way. I love the old car real steel metal compared to the thin metal new piece of **** new cars.

 

The roof didn't sink when the 2 panels where cleco'd together with small strips. It was then tacked and still held shape.

 

Yes, big time.

 

So did the problem come as you welded or after you started finishing the weld seam?

 

I agree with this method. The honest truth is my employee (fantastic metal man) was on this job. It seemed to be going good but I came a little late to the party and now we're fighting the oil can.

 

If you had gap and added fill rod as you went the filler shrank pulling the 2 panels together. That's what caused the dip. Just keep working the weld joint and push the panels apart and as you do the dip will disapear.

 

From what I gathered once it was tacked & clecos where removed.

 

He also said it was supported from the underside when It was tacked.

 

I often do skip welds and finish them as I go. It seems to keep movement to a minimum and much easier to work out as you go. Be patient not to over stretch as you go.

 

I normally would agree with this 100 percent but I'm wondering if because it was supported when tacked (not after) & the lack of crown if it needs something to either hold it up or more shape or.....

 

Did the 2 panels have same crown prior to welding? Was the support system actually holding and creating the shape?

 

Sorry for the late response. The panel shape was the same but he used the support to hold the roof up.

 

I always worked it this way...

 

Metal shrunk in the HAZ area. Metal needs to be stretched back out around the weld seam. Which in turn will relax and let the center section come back up to its original shape.

 

Metal always shrinks when you weld it. Shrinking it more may cause more problems, UNLESS it was overstretched when your welder was hammering and dollying it. Did he do this? Did he stretch the tack welds as he went along? (sounds like he did not) Did he hammer each s***ch of weld, or did he wait until it was finished to hammer and dolly...this method is OK for experienced metal guys, but not recommended for beginners, or for doing long flat runs of weld.
For panels this flat and long, I recommend staying in control of the metal by hammering each tack, and each s***ch, AS YOU DO IT,so you constantly keep the metal in it's correct shape. If it goes bonkers, you know it was the last thing you did and it's easier to correct it, than waiting until the end, when you can't tell where the biggest problem is.
It really takes an experienced eye...AND hand to fix it now, though. When I am showing guys how to do this, I tell them the most important thing now is your eyes. Using straight edges, or contour gauges, watch and monitor your panel closely, as you do small corrections...work only on the weld seam! You should be able to see or measure if the metal is getting worse, or better as you hammer and dolly it. It's not easy, and will take lots of time and patience, but a good hammer man should be able to work out that oil can.
Good luck!

 

chopolds gave some very good advice. Quote= "staying in control of the metal by hammering each tack, and each s***ch, AS YOU DO IT,so you constantly keep the metal in it's correct shape." And this; Quote="watch and monitor your panel closely, as you do small corrections...work only on the weld seam! If your not sure where the problem starts or ends you may want to consider a .030 cut off disc and cut through the weld seam in just the effected space, get your shape back and re weld it.
The Wizzard

 

Thought I'd give this a quick update. I appropriated the advice on how to attack the top. After messing around with what we had I decided I didn't like the way it was turning out and went about it in a new way.

We are lucky enough to have an old wrecking yard close by so we made some templates and went shopping for a new donor roof skin.



We then went about it like we would when we fill a top or do a 4 corner chop. I'm much more satisfied with the overall outcome. It has a more even/correct flow to the top.


Thanks again to everyone who pitch in!