Part of this issue was due to the design of my cradle, and the other reason was because I refused to try to set these rivets on the most extremely curved surface of the LE working solo, due to the extreme likelihood of completely screwing up the entire LE assembly. the LE is a little deeper than 1.5 feet tall. To successfully buck these remaining rivets, you have to have be able to reach from the back side of the LE all the way to the forward section where the remaining holes are located. This is next to insane as far as bucking rivets goes, since the main idea is to keep the rivet gun and the bucking bar as close to your body as possible. The other serious complication is the need to hold the bucking bar at the correct angle with one hand, while holding the rivet gun also at the correct angle for the same rivet.
I knew from past experience with all the other skin riveting episodes of the tail surfaces that taking what amounts to a small vibrating hunk of polished metal (the rivet set), and sticking it in a gun whose sole purpose is to deliver rapid and very precise vibrating pulses that transfer to the rivet set, and holding another piece of polished metal (the bucking bar) on the other end the rivet, and trying to do all of this on curved surface, is a recipe for disaster when trying to do this alone.
I also learned from that experience that what makes a huge difference in the ability to set rivets like these successfully if you are working solo is that at the very least you MUST ensure that the entire work piece to be riveted is positively secured at all times and accounts for all possible directions and positions from which riveting will take place. Since the most forward rivets on the LE have to be bucked, and they are located on the most forward curvature, the tendency will be for the rivet gun to push the entire LE assembly backward. SO this has to be prevented at all costs.
the other decision was to ensure that I could bucker the rivets so that gravity is helping to force the rivet gun as straight downward as possible. The gun is rather heavy, and trying to hold the gun upward against the skin would become very tiring very quickly. So the best method/setup for this IMHO is to set the work up so the gun works with gravity and as straight up and down as possible. The pros probably have rotisseries that can lock an entire work piece into the just the right position as described above, or, they also probably have other hands from other people to help them rivet things together.
SO without additional help and without a professional rotisserie two work with, I cam up with the best solution that I could. It starts with unclamping the cradle and table top from the saw horses. The next step was also very important, and it was only after seeing something on the saw horses that it dawned on me what I needed to do. I realized that my saw horse assemblies came with metal frames from HD aviation supply, and that these saw horse frames had adjustable metal legs. Normally my garage work benches are high enough to allow the work pieces to be at a comfortable working height, but my problem with these benches are that they located up against the rear wall of my garage, and so I have limited ability to move around the benches to get best position on the work piece. It was for this reason that I set up the mini table on the saw horses in the first place - so that I had the ability to move around in any direction and put the table in any location to take advantage of additional lighting etc.
With that, I removed the cradle and table top and then adjusted the legs on each saw horse to add about another 8 inches of height. They were fine in their default "lowest" setting while setting the rivets with the LE in the vertical position, but to set the forward rivets of the LE I would need to turn the cradle on its side. T put the LE at the proper working height, I needed to add about 8 inches to the saw horse height. Turns out that this was pretty optimal.
After raising the saw horse height, the next trick was to figure out how to secure the work with the cradle turned sideways. After a lot of thought, I finally came up with a solution that worked so well that I almost thought about patenting it. It ended up taking no less that 10 bar clamps, and some of the them had to be changed out for different sized ones when I flipped it over to rivet the bottom and top sides of the LE. More on that later.
Next decision which side to address first - the top or the bottom. Recalling a post from someone while building their fuel tanks, I decided to set the rivets on the bottom side first, because the bottom is flatter, and less curved at the front than the top of the LE, and once you have set the bottom rivets the LE can set down on a flat surface without rolling around too much. For my solution the le stayed horizontally mounted in the cradle at all times, but doing the bottom side rivets sounded easier than the top so I opted for that.
SO the cradle was turned sideways, and the clamping innovation began. Once the cradle was solidly clamped to the saw horses and the make-shift mini-table, I was able to insert the LE into the cradle, but then it became apparent that I would need to figure out a way to clamp down the back side of the LE along each of the rear rib flanges to keep it from flying or falling out of the cradle. A search of my scrap wood supply revealed the solution. Here are the pics showing the setup that I used. These pics show the LE in the cradle with the bottom of the LE on top:
I had a 1x4 piece of wood tat was long enough to lay across most of the rear rib flanges, and then I needed some additional 2x pieces of wood to extend beyond the rear-most outer LE skin edges so that the clamps would not destroy them. This setup allows me to get my arm and hand with the bucking bar inside the assembly while holding the rivet gun on the top side with the other. A couple of 36 or 48 inch bar clamps to squeeze everything up against the forward part of the cradle. This is how the LE is prevented from slipping out of the cradle during riveting. The extra pieces of 2x that I used were remnant from the form blocks that I created long ago after using one of the LE ribs as a template. The only thing that I needed to be careful about was applying too much pressure on these clamps that might cause the forward sections of the LE to crus or deform against the cradle supports.
Here is s shot from the other side, and more shots that show the rest of the clamping arrangement, sing various pieces of wood to make it all happen.
It took 10 clamps to make it all work, but it worked great once I figured it all out. I had to use some additional 2x4 pieces as blocks to allow me to secure the cradle to the table and the saw horses.
The next decision was to decide which part of the LE rivets to work on first. Since I had more rivets to set to finish securing the sections of the outer skin to the subskin on the inboard portion of the LE, I chose to work on those first. I started out by setting the skin-to subskin rivets that secure the outer skin where it is cut out to receive the removeable section. These were the easiest to set because they were also the most rearward rivets to be set, so reaching them was easy, and setting them was easy too because they were also still on a flatter part of the bottom of the LE.
For some reason I only have a shot of the bottom side shop heads of these rivets after I bucked them. They are the span-wise rivets in between the nutplates at the top and center f this pic:
Then it was time to start setting those pesky forward facing rivets. I had to use combinations of the Fat Man and Little boy tungsten bucking bars to fit then in between the nutplates, rib webs, and other rivets. The process to set these 6 or 8 rivets along the strap portion of the outer LE skin took me well over an hour to complete. As expected, trying to hold the rivet gun on the most curved part of the LE at the front was NOT fun, and I had to contort my arms, hands and body in very unnatural ways to get everything to fit correctly before pulling the trigger on the rivet gun. None of this process was what I would call "fun," but when I was able to set all of these rivets, I felt pretty god about what I had done. I should also point out that even though I was using the mushroom rivet set with the rubber cup around it, on several occasions the rivet gun decided to have a mind of its own and would slide off the rivet head, causing me to reposition it and try again, and in some cases I had to replace a rivet because the head was so badly damaged from this that it was unusable. Fortunately the rivet gun air pressure must have been perfect because I never dinged up the outer skin at all. I was completely amazed by this after looking at the less that good job I did riveting the skins on my HS.
This next pic shows that I also had to determine the sequence of which rivets to set first, seconds, etc. For the area around the modified skin of the LE, I decided to set all "outer" rivets first, followed by the corresponding inner rivet, working from the rear-most rivets to the most forward, which is in line with Vans instructions. SO all rib flange rivets were set first, followed by the inner skin to subskin rivets along side. Thise process seemed to work well, and the outer skin was riveted to the ribs and subskin quite well. Also amazing was that I was able to use the AN426AD3-3.5 rivets as called out in the plans for the majority f this remaining riveting, except in the area surrounding the mod, where the 4.5 rivets were the correct size to account for the extra thicknessof those ribs and the subskin.
I also had to remove both clecoes in order to be able to position the rivet set on the gun in the right place. trying to keep tha damn thing from sliding around on the outer skin was a real pain in the ass.Trying to reach in and hold the bucking bar in the correct position at the correct angle, and hold the rivet gun the right spot on those curved surfaces was even m ore of a pain in the ass. I had to take my time with every single one of these final rivets, and I also had to recognize when I was getting tired and when to take a break. This happened often as I did NOT want to have to reset any of these rivets or risk damaging the LE because I was too stupid and too tired to know when to quit.
Much more to come on this later. The good news is that I think I got it all done. No more clecoes are holding this baby together.
KPR
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