GETTING BENT OUT OF SHAPE

Greetings!
It's getting near Christmas and I'm excited to see family members again. I've got three grown daughters located in Arizona, Idaho and Virginia and I'm planning on seeing two of them during the Holidays. I hope things look as rosy for my readers!

I took a repair job that my friend Paul offered me. An accident had caused a dent in the passenger rear door and he wanted it fixed so he could sell the car. I thought it might be interesting to show how to pull a dent using a stud gun. 

The dent was right across the accent line contour with a small gouge in the door jamb area below as well. It is a late model Ford and it seems to run and drive very well otherwise. 

I started the repair by taking the paint off the damaged area with a DA sander. I tried to keep the repair area to a minimum so I wouldn't have a problem paint-matching the panels later. Most of the time, when you paint one side of the door but not the panel next to it, it's difficult to get the paint to match. There are quite a few variables, the most obvious are the formula used to mix the paint and the care with which it's mixed. The distance the painter holds the spray gun from the panel and even the air pressure play a part in how the color conforms to the original. 

The paint store mentioned that the formula used to make the color had a note in the mix instructions that I should use an opaque red undercoat. This tells me that the color has poor hiding, or in other words; its a rather transparent color. I'll explain how I compensate for this later as I paint the panels.

The stud gun is a bulky, hand held device that accepts a small round-head nail in the tip. It's powered by 110VAC and when I put the gun tip against the bare metal with the small nail in the tip and press the button, it welds the nail tip to the bare metal. I placed the nail head in the deepest portions of the dent about an inch apart. I also made sure I put a stud at the body crease so I could be sure to restore that contour. 

The next step is to use the slide hammer that is a part of the dent pulling kit, to grab the stud and pull. The sliding weight on the slide hammer hits the stop and makes an impact that pulls the stud (and the metal panel it's welded to) out somewhat. It's up to the operator's skill and control to pull just the right amount to avoid making a bump in the panel that sticks out too far. 

Here's an image of the stud gun offered by the Eastwood Company. They've been in business for a long time and have reliable products specifically for the auto body craftsman. This one retails for about $370. 

The small studs are for replacing the small anchors to which you attach a molding clip that holds on chrome trim or the like. I've never used one of the small ones. I'm thinking they'd work well in my sling shot during the zombie apocalypse.

Using a body hammer to tap the potentially high spots while I'm pulling on the panel with the slide hammer, I can do a lot to level out the panel. Sometimes I use heat to shrink the metal at this stage.

The impact had actually stretched the metal when the dent was made, and by using heat followed quickly by cool it has the effect of shrinking the metal so it tightens up again. I use a torch sometimes and other times I use the heat tip supplied in the dent puller kit. You need to have the cool source ready and I usually use the blow gun at the end of my hose for that, although I've successfully used a rag with cold water. Failure to do this, especially on a larger flat panel like the hood or the middle of a door panel, will allow the panel to flex, like when you press on the lid of an empty metal can and release it again. In fact, the condition is referred to as the "oil can effect". In the case of this job, the damaged area in right over the body contour and that helps minimize the oil can effect. I didn't have to shrink the metal for this job.

When I'm satisfied with the shape of the bare steel, I mix up some body filler by adding the accompanying catalyst, and carefully spread it around the worked area. I don't want to use too much because the more I add, the more I have to sand off to get it right. I find that I use more or less an amount the size of a golf ball on the first application and much less the second time, if needed. Usually needed. 

I begin sanding with 30-grit sandpaper using a firm sanding block. It's important to use the coarse grit at first to properly shape the repair area. If you use 80-grit, for example instead, you may have waves and dips in the finished surface because the lighter grit isn't "aggressive" enough to flatten out the high spots, it just smooths them out. 

I can tell from the sanding marks in the photo that I'm still high on the left but low on the right. I had to make two more applications of body filler (bondo) before I was satisfied with the repair. At the time of this writing the car is in the family spray booth in town and it has a couple of applications of primer already applied. Others in the family had to use the booth over the weekend so they courteously moved the car out so they wouldn't get paint on the car. I'll get some photos of my progress on the paint later today. Thanks for looking!

Doug