the hood in the previous post is from a brick built mill, which is always round (these were most used in towns) - thached mills or mills covered with wooden planks ar most of the time with 6 sides. hoods vary with different mills, but the basic form you used is right.

here two drawings with details. (the big image is clear)

and oh, yeah, the units are a mystery to me - in sketchup i use real-world-measures

koosie

"The light at the end of the tunnel may be an oncoming train"