The Stovebolt Site Forums The Shop Area Paint and Body Shop Cab corners are not easy :(

I ended up with oil canning. Most of it is where it won't be seen. Some of it is, and I have had zero luck t reducing it with videos and instruction.

That being said, they are smooth with very little wave now. It was a skim, block, repeat until I was satisfied. Thankfully most of it wont be seen, but the corners will being a step side.

Yeah, oil canning on those flat sections can be a pain. I'm still working on oil canning on my cab roof, even with coaching by the resident expert.

As long as you can block it without the oil can cycling you'll probably be OK.

Klhansen,

That kinda what I figure as long as it stays put I will not worry about it. I have a hole in my roof from a CB antenna. I recently decided to simply put a rubber plug in it vs trying to wend a blank in it to try and avoid the situation you have.

I had a couple of holes in the roof that had mickey mouse ear signal lights installed. I didn't like the look at all, so I welded them up with no problems, although they were in a spot with quite a bit of contour.

The oil canning I had was because someone may have jumped up and down on the roof and dented it. I may have helped a bit getting those dents and ridges out, but was trying not to do any on-dolly work.

Oil canning is a relative word and so is wavy. They can be natural or caused by welding or grinding heat. I don't know how much or large of a patch was done. You can see all the effort was done, with the large dimples the factory put in, to elimimate oil canning. Very common in sheet metal design. Any change in direction of the metal will stiffen. Dimples, corners, flanges, indentations, a bracket, etc. Looking at all the changes in direction in the areas you show, I don't believe you did anything to cause that unless you did not cool or go slow during welding.
Sounds like you can live with wavy. It's not the only "wavy" place on the truck I suspect. If it actually oil cans in a bad way you can add pieces of angle by rivet or spot weld in unseen areas.
Generally "oil canning" means the metal is popping in and out all the time and may make noise. Wavy is wavy. The terms are intermixed often. Warp is used to describe user caused stretch/shrink......which then is sometimes called oil canning or wavy

P.S. We can't see the "wavy". The patch job looks really good from my house.

Like bartamos said, oil canning is when the metal is somewhat stable in two positions, popped in or out. When you push on it and it "pops" and goes to the second stable position, and then pops back when you release the pressure that's a true oil can. It can also stay in either position and need a nudge from the opposite side to go back to the first position. If it doesn't pop it's not an oil can, but just a soft spot.

Looks really good from here!

Do you have pictures of the welds/repairs before the filler went on?

Pics of before. if you push on it, it will can, but it comes back to its happy place. Either position will be a wave no matter what. I have eliminated most of it with skim coating, but it looks like it was there from factory so I don't want it too perfect.

No judging my welds. Sometimes things go smooth and other times I have to go over it multiple times to get it right. Good thing someone invented a grinder.

You can see when I made the cut it relieved it some? Who knows. I am learning there is nothing that can't be fixed with a welder hammer and some filler.

Where is the oil can located, is it easily cycled back and forth or does it take a little effort?

I've done all this I'm going to say so....... My suggestions:

Your gap is too big, that may casue extra heat/welding to close up the gap.
I don't recommend those clamps. I bought those too, way back. They make too big of a gap. I did grind down the blades thinner. But it does no good unless you size the patch correctly. I now use vice grip clamps, vise grips, magnets, tape, my hands. The width of the gap has been discussed. From no gap to small gap to other. My results say fairly tight gap. I have also started, when possible, to tack the outside, then weld the inside, then back to finished the outside, then grind outside. This helps me prevent blow thru and is stronger. When you grind, you alway have places/holes yuo need to repair and regrind, So the back side welding helps again to prevent blow thru.
If a person wants a tight gap, like I do, you can not use those clamps you show.

Of course all this welding I speek of is done one dot at a time and I have a paranoid attitude and cool each dot. No matter how long it takes, warp is forever.

Rewelding just initiates another shrinking cycle at the weld dot. Best avoided if at all possible.

In my case it is not possible, I always leave a gap I didn't see or holes in middle of dot. I have seen pros videos and they reweld every time. When you are quick zapping dots trying to get penetration and not blow thru and not heat up, you will miss a few spots. When you shine a light behind the weld......yipes!

My quick air gun has seemed to prevent any issues with warp or I am lucky.

Yeah, I've left a few pinholes in my welds also. I agree it's not always possible.

I have never planished. Planishing is over rated and over emphasized. It also may be mis-characterized as "relieving stresses" I am not buying thst story. Here is what some welding sites say.

"Planishing is a quick inexpensive means of reducing weld build up and improving surface finish. It is similar to a steel mill cold rolling operation only it is limited to the localized area of a weld."

Smashing a weld dot may streatch the dot thereby stretching the gap. If this helps a person fix something, then do it.

Planishing can take care of some problems. Try MPandC's demonstration (see the sticky thread up on top of the P&B forum) of welding two strips of metal together with zero gap and watch them overlap as you start from one end and put dots spaced out along the weld. Planishing expands the dots so that the overlap disappears. You might be able to get away without planishing but you'll likely wind up with a valley along the welded seam, especially along a curved panel patch.

Robert is the man, no doubt. Do what he says. I just weld stuff/patches. I'm not a paint and body person. Just giving my experience and observations with DIY.

I may be misunderstanding what you are talking about, but growing up in a bodyshop when you could push the metal in and it would stay, and then get it to pop out and it would stay, the metal was stretched and needed shrunk. There was three was I remember to do this, one was a brazing tip and a bucket of cold water with a sponge. You would heat a small circle pretty hot and then throw the cold water on it and strink it until the metal stayed stiff. The second was taking a body hammer and using the sharp point to make a bunch of tiny little dimples that will take up the slack of the stretched metal. The third is similar to the first, you use a dent puller that welds the studs and it has a fitting for it to shrink the metal.

Yes, there's excess metal somewhere. Welding in a patch can shrink metal in one area, creating excess metal and oil canning in another adjacent area. You could demonstrate that by heat shrinking part of a perfectly flat sheet of metal around it's perimeter and winding up with an oil can.

Looking at the attached picture, barring any efforts to planish (stretch) the weld dots after welding, the shrinking effects at the vertical seam will have a tendency to pull the door opening rearward, widening the door gap at that area. (verify with straightedge against folded flange). I also agree with the above comments of the gap being too wide, this allows the panels to pull together unabated. The horizontal weld seam will have a tendency to pull that flat area together (pull front and rear area toward each other), noticeable by an in and out wave adjacent to the weld, and further up (blue circle) you may see an oil can that was likely protruding outward until you pushed it in. The corner where the two welds intersect, due to compounding of the shrinking effects, will normally result in a pucker in the corner (red circle). This pucker may also have a tight oil can on the lower end, the top should be real tight. The transition where the weld wraps from the side to the rear will tend to pull inward as the weld through that area shrinks, another thing that can be verified with a straight edge, hold it perpendicular to the weld.

If my presumptions are correct, all of these defects are attributed to weld shrinkage and failure to adequately planish out the welds. The problem with using filler over an unstable oil can is that it may still cycle in differing temperature changes where it pops the other direction on you.

Its right above the corner patches. It's a combo warp can issue. It takes effort to get it each way so I am giving up on it.

This has been my experience. I have considered it a good thing as it has made the final bodywork easier. A slight low is easier to deal with vs a high.

The attached shows a top-down pictorial of the scenario you have on the corner. The blue lines would be your outer profile, starting at the door jamb to the left, and working around to the rear of the cab. When the weld dots shrink along a length of weld like you show, it will also shrink the overall length unless the welds are planished. When the arc profile shrinks in length it makes a shorter arc, or in essence, pulls the metal into a valley. The side effect of gathering this metal tighter together is that puckers and oil cans will form. You get rid of these side effects by planishing the weld using hammer and dolly to add stretch back into the equation. When the weld stretches throughout the arc, it will bring the metal back out where it belongs and also release the tension that is forming the puckers and oil cans. When you reinstall your door I fear you will see a wide gap at the bottom adjacent to the vertical weld, where the shrinkage occurred. Planishing the weld stretches this area to push the edge of the door opening back where it belongs to restore a parallel gap. Welding without planishing the weld to counteract the shrinking effects is just an open invitation for all the issues you are having.. The process is discussed in the Mig welding tricks sticky thread.

"This has been my experience. I have considered it a good thing as it has made the final bodywork easier. A slight low is easier to deal with vs a high."

This is a very practical and good way of looking at it.

I have recently read about this strategy. I will have to try it.

I decided to chase the oil can. Got to the end at the top of the stamped relief on the cab on both sides. I made it good and flat around the corner and behind the bed post. After that I am done with it.

Wow, a good reason to never use those sort of clamps, way too big a gap. When I have done that sort of work I use as close to exact fit as possible and use a magnet to hold it in position. And have pretty much no gap.

klhansen The 1970 lead body man I worked with would take a FLAT round face body hammer,heat a nickel size spot red,swat in down on a flat dolly. That oil can would be gone after about 3 of those. Let it cool off grind off mill scale check with a body file,prime it. Maybe put on some tooth paste primer (from a big 3m tube) kinda thick let dry block it.

Well, it is almost there. I chased it up the first panel and around to where the bed will hide anything else. Good enough for me. I need to learn to put more filler down than I think is needed so I don't have to keep laying it down and sanding again.

I all metal is now back in epoxy with a couple layers of high build. Just a little more finish work and the cab is done. The ridge on the cab needs the most work still. Primer made it stick right out. Hood is still wet in pic, but I am very happy with how the hood is progressing. Not sure how, but two pics of hood ended up in there. Fixed it for a pic of roof. You can see the filler bulge on the right and left of the ridge.

Looks great!

X2