Front Wheel Arch (Dog leg) repair continued

With the inner skin now firmly welded into place (although still not sure if it is in the correct position) I decided to get the outer skin fitted. As I started lining up the outer skin I nearly forgot to fit the bumper mount I'd cut from the original wheel arch. I dug the bumper out and lined it up, bolted the mount to the side attachment bumper lug and clamped the mount to the inner skin of the arch. I played about with the adjustment of the bumper to get a central position then marked around the mount.
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I then cleaned all the paint off all the contacting surfaces, this needs to be done when spot welding. I dragged the spot welder out and 2 minutes later the bracket was welded in position. With the outer skin trial fitted I then cut the back edge of the mount hole to even up the shape.
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With the paint cleaned from the position of the spot welds for the outer skin I clamped and migged a few tacks welds on the inside of the skin, checked the door gap, the sills curve and the curve of the door. With everything positioned right I started the spot welds from the centre working to either end. When getting to the lower step I needed to push the inner skin up so that it would mate with the outer skin, doing this pulled the outer skin in from its flush position at the top curve about 2-3mm. I was also left with a gap between the skins on the top curve that I mentioned in the previous post, Although better than it was I'm really not sure how to sort this out, think I need a break for wheel arches and a fresh head to sort this out.