With your last pic i understand why the dia was just 60 mm. in the file you add here earlier, it is not the FXI25 that you showed in the beginning of this tread.
I didnt understand it in the beginning as the PDF indicated much bigger dimensions, and that dimensions made sense comperred to the width.
But i did take a brake from my numbers today and give it a og with this D = 60, and i was pretty close to the messurment on the inside the way i did think it was constructed.
Roof angle is 35/ 20/ 10 degree on attached.
I think same way as Andy, make 2D on world first, then it is easy to make and just rotate 90 degree later, or use it to take meassurement on if you want to draw it directly in 3D.
Blue and green are sweep paths, thin red is helpline, thick red is outersides of frames.
3050 on the top roof is what controlling the rest of the roof.
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