Sill Patch Welding

Today I welded in the patch panels I fabricated yesterday for the lower sills, right and left sides. The stock I used to make the patches was 18-gauge galvanized sheet metal. Galvanized metal can release some toxic fumes when it is heated, as in welding, so I am always careful to work in a well-ventilated area and also take the precaution of removing the galvanized coating from the edges of the metal I’ll be welding. I used a wire brush along the edges of both panels on both sides of the metal before getting started.

My first step was to drill out the holes in each patch where the fenders mount onto the sill. I used a 3/8″ bit.

And I repeated the same on the driver’s side.

I found some nuts that seem to fit the bolts that held the fenders on the one side that hadn’t rusted out, though I’m not sure those bolts were original. In any case they were a 5/16″ 24-pitch nuts. I welded them to the inside of the patch panel using my mig welder and moving around the outside perimeter of the nuts using small spot welds.

Here you can see the nuts through the holes I drilled from the underside. The holes are oversized a bit but will allow clearance for the bolts to go through.

Then I held the driver’s side patch into place and tacked it with three spot welds at the corners.

And then I started welding across the top. My technique is to weld the metal into place using numerous spot welds, rather than trying to lay down a continuous bead. This way I am able to keep everything relatively cool and yet still get good penetration of the metal. I worked in three clusters along the top of the patch, welding a spot in each cluster and then moving on to the next cluster.

I worked my way all the way around the bottom of the patch in this manner. I had to do some hammering of the patch with my 5-pound sledge hammer to bring it into shape along the way.

Then I moved over to the passenger side. After ensuring it was a good fit I tacked the patch in the corner.

On this side I wanted to get the top welded in first so I could make the other edges fit and manipulate the shape of the panel as necessary. So I worked across the top with spot welds, allowing some time to cool in between welds.

Then I moved down the right side and then the left side of the patch.

And finally I welded the bottom.

And I finished off the process by grinding down the welds using my angle grinder.

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