Z Bracket Prep Part 4 - A post of how NOT to do things

As stated in my previous post, I had messed up one hole of the 3 inboard bracket holes due to a drill press setup screw up. What I had tried to do was utilize a line that I drew on the short side of the flange to finish drilling the final holes in the part. Here is the really messed up way that I tried to do this:

Long story short, DON'T try to drill the flanges this way. It is much more reliable, but not necessarily fool proof, to drill them from the OTHER side, or the long side. You know, the side that I previously said should not be used because it did not account for the thickness of the web of the Z bracket. SO this means that the reference line used to mark the locations of the holes should be drawn on that side of the flange and drilled from that side as well. As you can see from the pic above, I had to resort to shims and other pieces of wood to support the flange, and this just did not work very well. Flip it over and drill from the other side.

This pic shows the result with the misaligned hole on the right. The part is now scrap:

Still waiting for my new Z brackets to arrive so I can measure, mark, and attempt to drill once again. I only ordered 7. Hopefully that will be enough! Actually I ended up taking the inboard bracket I had started for the right wing and used it for the left wing by simply turning it around 180 degrees.

And now for the next thing you should NOT do when working on the fuel tanks. During the same work session, I had been working on Z brackets and back drilling holes for several hours. I had also worked on filing down the bumps created by the relief cuts of the nose of each of the tank ribs, just as I had done for the leading edge ribs before. Now it was 11:00pm, and I decided I wanted to go ahead cleco the tank ribs to the fuel tank skin before I went to bed. I removed the vinyl from the inside of the tank skin,  PLACED IT IN THE CRADLE PER DAN CHECKOWAY'S OWN RECOMMENDED PROCEDURE as well as that of several other builders, and started positioning the ribs. My thought at the time was that this was the same shape as the LE, and so I should be able  to cleco them together the same way that I did with the LE ribs and skin. The only thing that was any different was that the tank ribs were shorter, and the skin was thicker.

Again, long story short, I found out that this is absolutely the WRONG thing to do. For some as yet unknown reason to me, the tank ribs do NOT conform to the LE of the tank skin very well, and because the skin is thicker it is much more difficult to try to force the ribs into the position so that the holes would line up. I started with the skins in the cradle and found that I was able to align and cleco all the holes on the top side of the skin and ribs, but getting the bottom skins to line up was next to impossible.

Knowing that the LE ribs were also stiff at first, I expected some resistance for the tanks ribs, but certainly not as much as I encountered. I started attaching the top side from the forward most hole to the rear, because I found that this most forward hole would line up with the rib the easiest. With much difficulty, I was able to push hard enough on the rear flange of the two most outboard ribs and cleco the bottom holes. Then I switched my attention to the most inboard rib, again with everything still in the cradle. While trying with ally might to push down on the rear flange of the rib with my left hand, and a cleco in my cleco pliers held in my right, I tried desparately several times to get the most forward hole to line up. When I thought I was close, I would apply pressure to the cleco with the cleco pliers while I tried to force the cleco into the holes. UNfortuantely this went bad, and I did something that I had not done in quite a while - placed two very deep and very pronounced scratches in the skin as the ends of the cleco gave out under pressure and slipped out the hole, scraping there way up the bottom side of the skin a good 6-8 inches as shown below:

Now I am faced with having to decide if this is salvagable or not, and worry even more because this is part of a fuel tank assembly, and the last thing I want is to have leaks starting from this area as a result of this lovely example of stupidity on my part. In short, there has not been a leading ledge on this entire project that I have not managed to ding up in some way, shape, or form, so as a result they are my least favorite of all the parts of the airplane.

I said more than a few choice words at the top of my voice which I am sure woke up half the neighborhood, threw my cleco pliers on the floor in disgust, and went to bed. After taking a day or two to calm down, I assessed the damage and decided to keep moving forward. Step one was to get my ass back on VAF and do the research that I should have done in the first place to confirm all the countless others that have encountered the same problem and discover how they resolved the problem.

I found one post in particular that clearly spelled this out. Step one - take the damn tank skin out of the cradle and place it on a table or bench where you have access to move it freely back and forth from top to bottom. I put down two layers of foam padding on my work table and placed the tank skin on that.

Step 2:Every single rib must be attached at the 2 most forward rivet holes on the top and bottom of the tank skin and ribs. Once this is done you attach a few more clecoes on either side of the tank skin until each rib is in place.

By leaving the tank skin out of the cradle it does not compress the LE of the skin as much and therefore the ribs can be pushed into place much easier. Make not mistake, this was still no picnic for me. And before any others start chiming in about my rib flanges not being straight - they all were - straight as an arrow, and the flanges were all 90 degrees to the rib web. It still took some maneuvering and some pressure on each rib to get each of those first two holes to line up. Remember to start by tipping the skin up on its nose, cleco one side of the LE, and then work to line up the forward hole on the other side. Also make certain that none of the other holes have clecoes in them. I found this to work the best for me, but I tried several different methods posted by several individuals to get this to work. Each rib posed a new challenge so they all required slightly different techniques to get these holes started. If you were lucky, you ended up with this for starters:

After this you can start applying clecoes on both sides.

The top side all done:

And the bottom side:

And then you are left with this rather ugly looking site. After all that work to remove the bumps from the LE of the ribs, this is what you get:

Not a real good fit. According to other builders it is my understanding that this is normal.I guess I would expect this to be the case, since each of those separated sections is actually straight and not very curved.

I could have saved myself some aggravation and maybe even damage to my tank skin had I researched VAF. Problem is that I did not think I needed to, because even Checkoway said to use cradle. There are certain parts of this build that are anything but easy, and this is definitely one of them. Tomorrow I will post more pics of the fitting of the tank to the wing, but will end with this last pic as a sign that hopefully things are still coming together. Again, my goal is to finish the wings by the end of this year, and the fuselage by the end of next year.