Thanks for the both replies. They were very useful. I did final bendings and moved on. I found out that the tip that bending should be done a bit further than the final angle was good. As when you open the skins a bit when putting spar there, it does bent trailing edge back a bit and it becomes pretty straight (from leading to trailing edge direction). Instead if you have not bent it enough there will be easily "bump" like in the drawings, but this "negative angle" method seems to really work here.
"Approach this gradually" -- yeah, I used hours to finish my bending. It should be straight forward thing: just bent it to the right angle and it shouldn't take more than few minutes next time.
