[Old_Green]

I added a couple of gussets to the upper hinge mount. my welding looked pretty rough, but they should hold.
I also found that a 1/2 inch OD steel tubing fits very snug into the hollow in the window frame and I can fit about 9 inches of tubing across the seam with 4.5" in each side. It should help keep the frame sections straight, and it will add strength to the frame when its all welded up.
I put 3 holes about an inch apart on the top side of the window frame on either side of the seam area to use to weld the frame to the tubing. Then I inserted the tubing into the frame sections, and clamped everything in place to check all my measurements.