Originally Posted by bkervaski
The goal here is to make sure the skin doesn't pull on the part underneath and develop a stress point. You want it to go out a bit and then start the curve. It took me more than a few attempts to get it just right.
What are you using to do the "roll"?
This is correct. The proper technique is to insure your Spar is being held down securely then press down hard on the skin with the bar and pull away as you roll. Try to keep the bar flat on the table while you roll it. We used to have a custom solid steel bar, very heavy compared to EMT. This helped to keep the skin flat on the table as the “roll” was being executed. This is hard to do solo.
It looks like you allowed the bar to rise off the table causing the skin to bend at the Spar. You don’t need the skin to match the bar radius. The bar is just helping to form the curve until you can join the two halves without induced stress.
It’s not too late. Carefully bend the skins back so they lay flat near the Spar, then roll it as above.