Fixing oil canning metal

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Evil oil can[ddd

The roof and doors on your cab are stamped domes. The dome shape is what gives that large expanse of metal it's strength.

When you cut and weld the dome sheet metal shrinks. This removes the tension, and allows the dome to collapse. Some times just enough to oil can, some times a collapse of more significant.

On the roof panel I found it needed to have hammer and dolly work to restore the dome prior to doing any cuts. This relieved any unwanted tension and distortion before the cut.

After the cut the weld needs to be done slowly to prevent introduction of large amounts of distortion by way oh shrinking the weld area.

I use MIG and but weld the joint. To hammer and dolly the weld, the weld needs to be ground very smooth. The ability to hammer weld is very limited D/T the additional hardness of the MIG wire weld.

Once the weld is ground to the same thickness of the surrounding metal, on the inside and out, you can start to hammer and dolly to repair any distortion introduced by welding.

I have found that the oil caning on my door and roof was caused by the dome being shrunk, not stretched. To repair the oil can I use soap stone to mark the very outer edges of the oil can area.

Now you to grow muscles. I use a large surface area dolly with a slight crown that closely matches the profile of the desired dome. The hammer I use is very flat. This allows the metal to form over the dolly in the desired direction. I used a lot of dolly pressure. In areas I could not reach I used an adjustable pipe Stand modified to support the dolly. I dollied the weld area first, then started on the outer edge of the oil can area. Thousands of hammer blows moving the metal very slowly follow the outer edge of the oil can. Recheck where the edge moves to, mark it, more hammer and dolly. Hammer in a pattern that will reform the original dome shape with out raising localized high spots.

The door on my passenger door was damaged and collapsed from impact. I repaired the damage and misinterpreted the oil can as stretch. I proceeded to shrink the skin in order to eliminate the oil can. I collapsed the entire lower door dome:(

Much hammer and dolly work was required to restore the dome. I did this before I did the roof and learned several lessons.

This is what I did. With out seeing your roof, and the condition of the roof damage preexisting the chop, I can't help much. I did find several small areas on the roof that needed shrinking, but the majority required stretching. The most important thing I found was to grind the welds so they closely resembled the surrounding metal in thickness. Any additional build up will limit your ability to metal sharp the area.

Hope you can find some helpful points you can apply to your situation.

Try the pipe stand dolly. A lot of effort, but it gave me the ability to apply enough pressure resulting in less hammer work.
 
Great reply gold and good to hear from you.
I took care of the oil can situation with a hammer and dolly.
More or less just went over the whole front of the roof area. Kind of like a manuel plannishing hammer.
I figured that I would try that before the torch/shrinking method.
I talk about it over on the build thread.
You are correct in regards to hammering on the mig welds. Even though I use an "easy grind" wire on body panels the welds are still very hard.
Back when I was a younger man and was learning to gas weld we did what was to refered to as "hammer welding". Welded and while the area was still hot used a hammer and dolly to A. Relax the area and B. To flatten down the weld as it was still fairly malable yet. But the term "Hammer welding" really means the very old style of welding where two pieces of metal are heated to almost molten and then joined by hammering them against an anvil. Black smith stuff that is.:)
Torchie.
 
I saw a real cool tool a while ago and had a serious temptation to buy it. A panel beater. google that and look at the U-tube videos.
 
I saw a real cool tool a while ago and had a serious temptation to buy it. A panel beater. google that and look at the U-tube videos.

I was thinking about trying to build a planishing hammer with a lightweight aluminum frame to get the roof hammered out where needed...

I have some oil canning as well that I'll be working on soon.
 
I cheat, I use a stud gun with a shrinker tip.
Great idea Mike.

I saw a real cool tool a while ago and had a serious temptation to buy it. A panel beater. google that and look at the U-tube videos.

I was thinking about trying to build a planishing hammer with a lightweight aluminum frame to get the roof hammered out where needed...

I have some oil canning as well that I'll be working on soon.

I have seen some very nice hand made plannishing hammers. Most used an airpowered chisel/hammer for the hammer side. I have a hard enough time getting to work on my project these days. If I start to build my own tool.....Mamasita.:)
Torchie.
 

Interesting tool gold. If I was working on late model stuff like that jeep that I put back together I could justify it. But I question weather or not it would pull a dent out of that old Ford steel that our trucks are made of.
Back when I did body work for a living and we used the screw end type slide hammers, we had dents that we could hardly get to budge.
The fenders and hood on that Jeep felt more like fiberglass than steel to me.
Torchie.
 

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