[JUDGE3]

Ok so as a rookie in welding 101, I almost feel a bit silly. but not really because I am elated that the help I got from you guys worked. and I very much enjoy learning techniques working on cars.

I just got rollin this morning and had to stop and report in.

I planished the weld(s) striking directly on the weld backed up by the best fitting dolly. It worked terrific to my amazement. I started a bit gingerly and was shocked how much warpage came out and even more shocked how the skin stiffened back up. then I proceeded to go over it 3 more times getting more aggressive each time. it just kept getting better! how cool.

I do still have some slight waviness left. very slight. I have more wire welding to add and you better believe I will planish each individual weld as I go. I am going to be curious to see if more welding\planishing I can get all the waviness out.

my panic has turned into fun stuff. may sound silly to you experienced folks but I was scared I ruined my nice new door skin.

man I felt like a pretty good metal worker as I kept planishing and it kept getting better! yeha

[roger1]

Fantastic!!!!
If you overstretch at all doing this, it would be easy to correct with a shrinking disc. Good investment if you don't have one. Check out the name I gave in my last post.

[Shiny]

Originally Posted by roger1

Fantastic!!!!
If you overstretch at all doing this, it would be easy to correct with a shrinking disc. Good investment if you don't have one. Check out the name I gave in my last post.

Ditto!

Glad you are feeling better about it and avoided damaging the skin.

I bought a shrinking disc and found it worked great. It was easy to use and felt like low risk for losing control. It was the only way I succeeded in removing stretched areas in my fender I had introduced by hammering.

[n20ta2]

The bottom of the door had a good wave in it from what I could see i think that was most of your problem right there. Glad you got it fixed.

[Greg Reid]

Originally Posted by roger1

We are not talking about metal that is stretched. We are talking about metal that has been shrunk and needs to be stretched.
The only way do that is with planishing and is done with a hammer and dolly. You strike "on dolly" which is striking the sheet metal with the dolly directly behind where your hammer will land.

Well, l would agree that planishing would stretch the metal but are you saying that oil canning is caused by shrunken and not stretched metal?
I always thought there was too much metal there. I don't know much though...

[roger1]

Originally Posted by Greg Reid

Well, l would agree that planishing would stretch the metal but are you saying that oil canning is caused by shrunken and not stretched metal?
I always thought there was too much metal there. I don't know much though...

Both can cause it. Depends on the natural crown of the panel too. One thing for sure though is heat causes shrinkage. Hammering on-dolly stretches.
I have a shrinking hammer but never have used it and don't know how. When I need to shrink, I use a shrinking disc.

Blasting too aggressively causes stretching. It's the peening action of the blast particles that does this and it can ruin panels. Common thought is that blasting causes heat on the panel and that warps it. This is not true. It's the peening that does it.
I never wholesale blast outer body panels. Only edges where you can't get to with a D/A or stripping disc. Occasionally I might blast spots more in the middle of a panel that has been welded in order to clean well it but I do it very gently. At an angle with low pressure.

[JUDGE3]

so it seems I've maxed out with great results planishing. some slight waviness remains. does this mean some shrinking with a disc is now needed? its not visually bad but can feel it by hand. filler will take care of it but if I can further use a technique and not need filler I will.

I do want to add a shrinking disc to my available tools, which one is recommended I see the one in this post lists 9", 5" etc, backing plate etc. which one is good for what i'm dealing with? kit?

[roger1]

Originally Posted by JUDGE3

so it seems I've maxed out with great results planishing. some slight waviness remains. does this mean some shrinking with a disc is now needed? its not visually bad but can feel it by hand. filler will take care of it but if I can further use a technique and not need filler I will.

I do want to add a shrinking disc to my available tools, which one is recommended I see the one in this post lists 9", 5" etc, backing plate etc. which one is good for what i'm dealing with? kit?

If you can keep your filler at 1/8" or less, you're good. Do you have any high spots now? If so, a little bit of shrinking disc use would most likely help.
I bought the kit with the large and small discs from Wray. The large one is what I use. I haven't really found the small one that useful.
I'd say get both and see what you prefer. Be sure to watch the video that Wray did on an old car's fender.
The shrinking disk is easier to use on panels with a lot of crown like that fender. The less crown a panel has, the harder it is to use. But in general, the less crown a panel has, the harder it is to repair correctly. And your door is pretty flat and going to be difficult to get it perfect. If the metal is tight and you are pretty close, you many not want to mess with it anymore.

On the '55 Chevy I own, I think there were about a dozen dents all filled with bondo that I removed. I figured at one time in the past the car was used by kids who sat on top at the drive-in theater. I used a hammer and dolly followed by the shrinking disc on all of them and didn't need to use any filler. Just a coat of polyester primer followed by a couple coats of urethane primer.
Those roofs have a bunch of crown in them and I found it pretty easy. It was my first time using a shrinking disc. I had to do some quarter panel work on that car too and had a much more difficult time correcting that. Did a lot of oil can fighting.

[n20ta2]

If your going to try shrinking definitely try the disc, high heat can cause a lot of damage if your not familiar with it. If you have a spare fender put a dent in that and practice first

[Greg Reid]

So how do you inspect and then determine whether an area needs to be stretched or shrunk?

[roger1]

Very hard to inspect and know. It's more by knowing what happened. Collision damage stretches. Repairing dents with a hammer and dolly stretches. Application of heat followed by cooling shrinks.

[Greg Reid]

I guess I got lucky with mine. I heated all three spots not knowing for sure how any of them happened. Took a little hammer and dolly work after heating but the oil canning was gone in short order after the torch.

[roger1]

Originally Posted by Greg Reid

So, if you have a panel with an oil canning condition, how do you know whether it needs to be shrunk or stretched?

If the panel has been worked and re-worked with heating and planishing repeatedly, you may not know and could be both. Stretched on one side of the oil can and shrunk on the other. It can get tough to correct if you let it get away from you.

[Greg Reid]

Good information. Thanks.

[JUDGE3]

question: does air quenching right away take the place of planishing?

asking mostly because some areas are not accessible to hammer and dolly.

I had an interesting learning point today while welding wire on my door edge for gap fitment. while tacking up the wire I had to hold it in place by hand, when I tacked it the wire quickly went soft and moved on its own. a great example of how quickly the steel absorbs the heat and reacts. I just didn't realize that was so drastic. easy to see how it warps etc.

I did notice air cooling quickly, I didn't get any warping.

[roger1]

The answer to your question I believe is no.
Also, I wouldn't expect to get any shrinkage with welding on a door edge as you've got the inner structure with the skin folded around it acting to hold it in place.