Sheetmetal Repair
Repairing body damage that goes through the paint is a different matter. The job often requires specialized tools such as pullers, hammers and dollies. Body filler and primer are also part of the deal. Skill and experience are also helpful when attempting to bring damaged metal back to its original shape. The overview here is intended to describe a few of the tools and techniques.
If the dent is too large to fill with body putty, use a puller and/or dent hammer to bring the sheetmetal as close to original shape as possible. When using a puller, file the access hole edges until smooth. Fill the hole with a MIG welder if available (adding a patch piece of sheetmetal behind large holes), then grind the slag smooth. A non-welding alternative is to apply mesh tape to the inside of the body panel behind the hole (if accessible), then fill the hole with body putty.
Next, remove any surface rust and flaking paint. A hobby tool or small drill fitted with a wire brush works well. Soft, dark and/or bubbled metal means rust—remove it down to shiny metal with a sander or a metal grinder or all your labor will eventually rot away.
Mix the body-filler compound per its instructions and use thin coats of filler to bring the body back to its original contour. Allow each coat of filler to cure completely before adding the next. Check for high spots with your hand or by lightly misting the area with black primer. Use a cheese-grater body file to knock down large high spots.
Sand the cured putty smooth with medium-grade wet/dry sandpaper, then go over it with fine and extra-fine grades, feathering it into the undamaged areas. Clean the repaired area with soap and water and allow it to dry.
