When building a custom, or resto-mod vehicle one of the most common modifications you can do is to "shave" or fill unused holes in the body of the vehicle. While I was waiting on metal to finish the Custom Running Board Build on Project Pile House, I decided to start shaving some of the unused holes in the bed of the truck. Since this truck was used as a farm truck most of its life, it's had countless brackets, hooks, and other do-dads added that left holes when I removed them. Even though the truck looks pretty rough in its current state, I have pipe dreams of this thing being a nice, solid truck someday, so shaving these unused holes is still progress!
There are a few ways to fill unused holes in the body of your car or truck. The techniques really vary on the size of the holes. The key tip is to make sure you take the time to setup your welder for nice flat spot welds and leave time for the metal to cool between each weld.
The easiest holes to fill are small holes about the diameter of a pen or smaller. For these types of holes I start by cleaning the area around the hole with an Angle Grinder and Flap Disc. Sheet metal on the body of cars and trucks is pretty thin (usually 18-22 gauge). So you won't have much forgiveness if you try to pile weld in the hole and you can end up with a bigger hole than you started with! For this reason I always like to use Copper Backers and Welders Helpers to back up and quickly fill the hole. MIG wire doesn't stick to the copper backer directing the weld to the edges of the hole and quickly filling small holes. Be sure to hit the trigger of the welder for a few seconds at a time. Properly adjusted MIG welders should make filling small holes only take a few seconds. A trick I use while the metal is still hot, is to take a Hammer and Dolly and flatten out the spot welds while they're still hot and soft. This will save you time and unneeded heat into the panel when you finish grind the panel with a flap disc.
Shaving larger holes and openings in the body takes a little more time and care, but can be done with minimal tools. I again started by cleaning the area with a flap disc and angle grinder, then I took some metal from our Patch Panel Kit and traced the opening I was filling from behind.
Once I had the basic shape, I roughly cut it out with Tin Snips. A grinder or power metal shears would work as well if desired(I've found for small pieces that tin snips work best). With the shape rough cut, I took the small piece to a Belt Sander or Grinder and carefully sanded the metal until it was just smaller than the opening I was filling (leave a small gap for the weld to bridge across).
Once the patch panel is a good fit, I used a Magnetic Welding Jig to hold the metal in place for the first couple tack welds. Once the patch panel is lightly tacked, I removed the magnet and again use a copper backer or welders helper while spot welding around the hole. When welding these larger holes you need to make sure you jump around and weld in an "X" pattern allowing the panel to cool in between welds. Like the smaller holes, I like to hammer the welds with a hammer and dolly to flatten them out as much as possible.
Once the hole has been filled and all of the gaps are closed, I took a flap disc and blended the weld into the surrounding metal, again stopping along the way to allow the metal to cool and avoid panel warpage.
With some practice you can shave and fill holes on the body of your project and leave no trace of your work. Below you can see how the repair area is almost invisible and would only take a little more sanding and a small swipe of body filler to have the panel ready for primer and paint.
Now that I have a few holes shaved on the bed of Pile House, I have officially caught the "smooth" bug and I'm already looking for other unneeded holes to fill and clean up the overall look of this project. Stay tuned for more updates as we keep working on turning this farm truck into a head turner!