And here is what it looked like after repositioned the tool and prepared to drill another hole. After the tool was repositioned I would re-cleco each new hole to ensure that everything was as tight and aligned as it could be. Then I would remove the clecoes, remove the tool, reposition, and do it all over again. The rear-most holes were the "easy" ones to do. The holes along the side were a bit of a different story.
After all 4 rear holes were drilled, I then had to start working on the holes along each side. This required removing more clecoes and applying my gorilla tape clamps in different places along the edges, while the clecoes would hold the rear edges down. This became a real exercise in figuring what had to be removed and what had to be secured in order to address each new hole. The holes along each edge were much stiffer and more difficult to lift the metal up in order to slide the tool underneath. This next pic is a bit blurry, but it shows how I setup for the first hole along one edge:
And the result:
I tried to keep both edges aligned by drilling opposing holes along each edge to avoid the metal getting tilted out of alignment over to one side. So here is the opposite hole being drilled:
After all the bottom side holes were match drilled things became difficult. I now needed to drill the same screw holes on the top side of the LE, but my approach this time would be to remove the part and trace around it onto my sheet of .025 aluminum so that I could produce a flat, unbent template for future use. My initial plans will require at least 3 separate parts - one with a clean leading edge, one of one light gun port, and one with the two desired light gun ports. This will allow me to do integral flight testing on different configurations, starting with the clean wing and gradually moving up to the "fun" wing if all prior testing proves successful. That means I will need a minimum of 6 of these parts - 3 for each wing. So I need to be able to make a valid flat template that will yield a properly sized part with #30 pilot holes located in the precise places on both the top and bottom sides of the part to match the screw holes in the subskin.
SO I decided to at least get the bottom holes located and the dimension of the template drawn and measured while the metal was still flat, before I bent it over the LE and over the top side to drill the remaining mounting holes. Here is the new part with all bottom holes match drilled, after I removed it from the LE:
Now for the really hard part. TO recap a bit from my previous work, the very first time I did this I used a file folder template and attempted to locate all the screw holes in that by using a free-hand drill bit and inserting it from the inside of the LE through the holes in the subskin. This method was less than accurate and therefore was also less than successful, since it left gaps along the edges of the part as a result of the less-than-perfectly-located holes that resulted from this former method. I secured this assembly to the table and match drilled all the bottom side holes to the new template.
After that was done I re-clecoed the part to the bottom side of the LE subskin, and then the fun began.
With no holes drilled or located in the top side of the part yet, my only means of securing the top side of the part to the subskin was to use more gorilla tape and my own hand pressure to keep it flush with the subskin while I used the strap duplicate to locate and drill all the remaining holes. There was no other effective way that I could think of at the time to secure the metal. It acts like a spring as you force it to match the contour of the LE. I could not put it in the cradle because I needed the LE possess the same "mounted" shape on the wing to ensure that the part has the proper fit. So this was indeed a challenge that require the brute strength of my hands and as much duct tape as needed to help keep it flush to the subskin.
Another problem is that I had intentionally oversized the long edges of the new part so that I could be certain that I would not have the same gap issues that I had before. The problem with this is that even though the edges on the bottom side were perfectly fitted and the holes were perfectly drilled, the top side skin was not the correct size or shape yet, so I had to go through another round of free-hand bending and aligning the part to the LE, removing it, applying the scotch brite wheel to remove small amounts of material, and then re-fitting it to the LE again. I bet I did this about a dozen times until I was satisfied that the top edges were ALL fitting properly. Then, and only then, was it time to drill the top side holes.
Here is a shot of top side after getting the rear-most holes drilled out with the tool and I started on the edges. I started on the rear most holes and worked my way toward the front, just like I did on the bottom side. The problem with this is that the bottom side had to remain clecoed in place all the time, so the entire part was locked down tight on the subskin, making it impossible to reposition and insert the tool in the forward-most holes. So to address this problem - guess what? - I had to remove clecoes from the bottom side as well as the tape and clecoes on the top side to reposition the tool for each new hole, so this part of the process took way longer than the bottom side did.
Actually now that I look at my pics I guess what I did was drilled all the rear-most top holes first, and then I started with the most forward holes on both edges. This is not optimal because it can cause bulging of the metal if any slack develops in the part. Unfortunately I did not have much choice in the matter because I need to make certain that the metal around the curve was in the proper position and conforming to the subskin properly in that area, so that is why I did it that way. In the end it turned out OK I think.
The curvature of this part was actually a bit more matched up with the existing LE, but still not quite. I have some more edge trimming to do on each long edge to ensure that it is fitting correctly, but I consider this effort to be a success. This was definitely much more difficult than I ever imagined it would be. And to think I need to make 6 of these things!
The last thing to note in this post is some feedback that I promised about the tool. It only cost me 16.00 from Cleaveland Tools, but while I was using it to drill the holes in the top of the part, I found out why it is not very expensive. The guide hole knob on the top that the drill bit fits into is only press-fitted to a hole in the handle. It is not welded or glued - only press fitted. For "normal operations I guess it would work just fine, but for my needs it fell just short of working 100% properly for me.
At one point, basically on my very last hole on the top side, I think the drill bit had some excess slag from previously drilled holes that got hung up in there, and the guide knob popped out of the press fitted hole in the handle. This did cause that very last hole to be misaligned slightly, but it was not bad enough to force me to have to make year another new part. I was able to remove the tool and used a hammer to "fit" the knob back into the hole, but after it came out the first time, it wants to come out much easier now, and so that kind of pissed me off a bit. I'll probably have to order another one to do the holes on the right wing when the time comes for that.
However, there is still one last chapter to this whole exercise, and I will cover that in the next post. it has to do with finishing the flat template after I finally got the top-side holes drilled in this one.
