On the RV-3B, the bottom forward lower longerons are riveted to the F-303 spar bulkhead. You can see this on drawing 21 pretty well, with the lower longeron riveted pair inboard of the F-303E side plate. For the plate and the spar bulkhead, see drawing 11.
The side plate means that the lower longerons attach inboard of the skin by .063. No concern, though, as SK-45 shows how to deal with that:
That seemed a bit of a kluge, frankly. I thought perhaps that I might be able to joggle these longerons at that intersection. Yes, the lower one was 1" x 1" and they were both 1/8" thick, but even so.
If you'll go back, back to post #240 or so, you'll see a longeron bending tool. Look closely. Notice how this is not a hydraulic press? And how there aren't any tool steel forms standing by? I noticed that, too. Both of these, I might add, would have increased my confidence considerably.
This has been a week that's just been too full of non-RV stuff. Here and there, I've had some time to play, though. And my scrap bin had a number of 6061-T6 angle extrusion cut-offs that were the right size and the right material and which I didn't seem to actually need at this moment. So I played.
After I ruined most of my 1" angle scrap, I'd learned the techniques.
1. Start at the bend farthest from the end and clamp the end in a vice with soft jaws.
2. Allow 1" for any compressive bend on the upstanding flange, and 3/4" for any tension bend on that flange. Allow 2 3/4" between bends.
3. Bend it a bit. Reposition the tool and correct any out-of-plane errors.
4. Move to the bend closest to the end.
5. Remember which way to bend it. Bend it a bit. Reposition the tool and correct any out-of-plane errors.
6. Go to the fuselage and see how far off it is.
7. Take it back to the vice and items 3 through 6 as needed.
Here's my successful trial piece. I've clamped it to a piece of straight angle so I could see the joggle. The bend on the left is marked 3/4" and it's from this piece, correcting errors, that I learned to make it 1".
Since I took that photo, I've joggled all four of the lower forward longerons and have yet to do the ones on the F-315 seat ribs. It's slow going but it is possible.
The pictures are also here
One small thing worth mentioning. You might ask, well, structurally, which approach is better? And the answer is that I think Van's method shown in SK-45 is better. It's slightly lighter, slightly stronger, and doesn't need a tapered shim on the transition section like my joggles do. However, the strength is only better if you make a careful fillet radius at the change of section. If you leave it sharp-edged, then the joggle is probably less likely to have issues in the distant future.
Or maybe not. The bending, after all, does introduce its own cold-working changes to the material. Want to see an extreme example of that?
In this bit of scrap, I was still using a negligible length to absorb the bend. And I positioned it at a #40 hole. You can clearly see the over-stress as the bend put the hole and the area at the edge in tension. And the hole has elongated, too. Scary, isn't it? That's why I changed the process to include 3/4" to absorb the bends. What did I do right? The mark to show which way to make the bend is a good thing. It's easy otherwise to bend it the wrong way.
This was scrap, remember.