Very timely post as I just finished my rudder yesterday. If there's an award for spending the most time on a leading edge, I think I may win. I used the "J" hook method and found that the small section was the toughest. The bottom section went together the best and quickest for me.
What I found/realized is that:
1) Nowhere in the plans does it give you an idea of where the apex of the roll should be. Perhaps this should be obvious..but it wasn't to me <smacks head>. The apex of the roll is about 1/2" from the the spar flange.
2) There should be almost no bend at the edge of the skin. The rivets go on the tangent. So, in essence, that area should be flat.....or almost flat If it's not, then the skin will tend to curl back in toward the spar when the proper bend is made (closer to the spar).
2) The pipe (or whatever your using) should be parallel to the spar...not parallel to the edge of the skin. If it's parallel to the edge of the skin, the "small end" will be closer together than the bottom (big) end after the bend.
3) The most important part of the bend is between the apex. It's also the toughest to spot to manipulate.
4) I learned that the top skin should be bent before the bottom skin. When the top is completed, the bottom skin can be manipulated under the top skin. This only needs to happen once as the bottom skin can be massaged without having to move the top skin out of the way.
For the lower section, I started with 1" PVC (1.315 OD). Placed it parallel with the spar as far from the edge of the skin as I could and still get the skin to bend 90 degrees. I followed the 1" PVC with 3/4" PVC (1.050 OD) just a bit closer to the spar. I ended with a 1/2" OD steel bar up against the spar flange, clamped it with "J" hooks, and massaged it by hand until I had all the bend I could. After that, the remaining curve was done by hand. There was very little left to do.
The first section (small) took about 3 hours to get right...and I'm still not completely pleased with the results.
The middle section took forever. Probably 5+ hours. Then I figured things out.
The lower section took about an hour and came out perfectly.
In looking at your pictures, it appears that the apex of your bend is too close to the edge of the skin. I'd use a smaller diameter tube or pipe and try to get the bend closer to the spar. This will bring the edges together without the fear of creasing the skin at the spar.
Hope that helps.
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Last edited by Reflex : 03-26-2017 at 05:48 PM.