Today was the day to start riveting on the skins. I was nervous about this for a couple of reasons, but mainly because it was putting everything together for the last time. Also, since I am backriveting these, it was something new to learn. In hindsight, I was worried about nothing at all -- typical in this project.
First off, I devinyled, deburred and dimpled the outboard top skin. I then clecoed both skins and the wing walk doubler to the right wing. I then undid the lower clamps holding the rear spar to the wing jig, because I wanted to remeasure how everything aligned. So, with the skins clecoed on, I used the smarttool to put the main spar level. Next I checked for a twist. I put out plumb bob and saw that they were at most 1/64" off, which I couldn't make any better. I did a quick calculation and 1/64" over 25" is about 1/100's of a degree. I guess I can live with that!
Next my dad and I worked on backriveting the skins on. This came very natural to both of us. I clecoed the wing from the inside out, so I could remove the cleco while he put the rivet in and got the bucking bar just right. A few hits with the backrivet set and everything was done. One thing I needed was 50 psi of air pressure to get things to set in about 1 second. I started out at 32 psi, which I normally use for AN426AD3-3.5's, but that wasn't making any progress quickly. I have to say that backriveting these skins makes them SMOOTH. The results are awesome. A big thanks goes out to Jack Savage for letting me borrow all of this.
A Bigger thanks goes out to my dad for helping out. The key to doing these top skins is good communications. The bucker and shooter need to be on the same page, especially on these top skins that get seen. We only needed to drill out one rivet out of the few hundred that we set.
Once the inboard skin was on, we moved onto the outboard skin. We got done one rib and were working across the main spar then the backriveting set broke!!!
This is a shot of the skins being clecoed inside out. With doing this, we were able to cruise through each rib. Probably about 5 minutes per rib to rivet once we got our system dialed in.
Here is what happened to the backriveting set. The bar fractured where the top pin goes through, which holds the washer against the spring. It scared the crap out of me when it happened, because all these parts dropped and something went shooting across the room. It took me a while to figure out what happened, but then I put it all together. I wasn't wearing safety glasses, because I figured what could go wrong? I was lucky the spring didn't get me. From now on out I will use them.
Here is another shot. Definitely looks like a manufacturing defect. I called the owner of it up to let him know, because I wanted to see if it was new, or from a top notch place like Avery that would stand behind their tool. It was a hand me down, and Jack wasn't concerned at all about it breaking, or even me replacing it. He knew where to get one in the future if he needed it.
Also, with the backriveting bucking bar I put some masking tape across the face of it to keep it from scratching up the skins. Worked well with no side effects.
I was thinking about going with the traditional shoot/buck method for riveting on the skins, but my dad and I agreed that this provided awesome results. I will get a new one overnighted this week so I can get back to work one night this week.
Since I had a bunch of free time, my dad helped me shoot the couple of rivets on the left spar that I drilled out and then we started to rivet on the leading edge. I got almost all of the pop rivets done when my hands just couldnt take any more. Instead of getting frustrated and breaking something, it was time to take a break.
Finally I riveted on the leading edge on the right side.
OK, I found more motivation (and time) today to work on the wings. First off, I wanted to seal off the tanks to prevent bugs from making nice cozy nests in them. My house is in the woods, and we have all kinds of critters around. I used these caps I got from Spruce -- On top of sealing off critters from the tanks, they also protect the fitting from getting damaged.
I put some tape over the drain valve with a small hole in the middle so air can get in and out as the temp and barometric pressure change.
OK, I got really motivated and finished installing the left leading edge. For some reason, this one went on way faster than the other one, or it did in my head. Next was onto the tank.
For good or bad (i haven't decided yet), I have pillowing on this side too, which matches the right side almost identically! Well, I guess I am consistent. I am too tired of losening and tightening screws from tonight to mess with it any more. I have all kinds of time this week to mess with it.
Last Modified: September 28, 2019