03/25/2018 Slow Progress

Last few weeks I haven’t made as much progress in the preparing work as I was hoping to make. A few of the distractions include getting a little busy at my day job that I have been leaving office around 7pm quite often, family obligation taking chunks of hours from weekend time, taking friends and co-workers up for multiple scenic flights(and being invited to have dinner after the flight) over the weekends, last but not least working on other airplane and project. Well, I guess the last “distraction” is actually useful for preparing myself to work on my own RV-7.

Eagle Annual

The annual condition inspection for our Christen Eagle II started on 3/10. I went to RNT to help disassembling the plane on that first Saturday. The following Saturday I went to a wild life zoo with my wife and two other friends, while our Eagle partners found a rib broken off and floating inside the leading edge of our top right wing. We’ll need to wait for more info from A&P and Aviat factory on how to repair this.

Bucking Rivets

While my wife was on business trip away from home, I spent last Wednesday and Thursday night at Shawn Li’s garage bucking rivets. Shawn has already built a RV-7 and flown almost 500 hours in it. He’s currently building a RV-10, and he needed some help on installing rivets on the wing. Since he didn’t mind a rookie like me working on his plane, I gladly accepted his invite to practice my bucking skills help holding the bucking bar. I have a few oops moments and created a few not-so-pretty shop heads, but Shawn was cool about them, accepting some of the not perfect rivets and only drilled out a couple bad rivets. All in all, I think (I hope) he is happy that two people really speed up the process for him, and I get valuable practice and many chance to ask questions on other items in the workshop and build process.

Storage Shelving

I ordered a 5 ft wide, 2 ft deep and 6 ft tall storage shelving from Home Depot. From reading builders’ log online, I figure this should be big enough to store most of the parts during build process. Because the unit is so big even when it’s packaged, I had no choice but choose to pay for delivery. It took about a week to receive the shelving, but it only took less than 2 hours to assemble it. I also bought a tarp from Home Depot the next day to cover the back of the shelving, so that if garage door opens when it’s raining outside, which is very common in Seattle, my parts on the shelving won’t get wet.

Garage Window

I replaced the wood and foam board blocking the garage window with some privacy films, so that I can have a brighter garage during the day. More importantly, I need to get rid of those boards so that I can install a window fan later to provide better ventilation.

Practice on aluminum sheet

Drilling

After marking the aluminum piece with dots as close as possible (2d to the edge and 3d between each other), I started drilling holes. After drilling about 8 holes or so, I noticed that it is getting harder and harder to drill. The drill bit did not seem to have the power and sharpness to go through the aluminum. I started guessing if my technique is incorrect. I tried to push down harder or lighter, and I tried to adjust the pressure on the trigger to change RPM, but nothing helps. Then I start to wonder if the drill bit is alright. After all those suspicions, I accidentally notice that the pressure reading of my compressor’s tank had dropped below 60psi. It turned out that the compressor has tripped the circuit breaker the very first time it was trying to start the engine. Since it’s my first time using air drill, I had no idea that it consume so much air. I didn’t realize something was wrong after drilling the first few holes and compressor didn’t restart. So although the compressor is specified using 15A, it actually varies up and down quite a bit on different days. After this interesting drilling experience, I moved the compressor to a different power outlet that has 20A instead of 15A circuit breaker. I drilled rest of the holes on that piece of aluminum without having difficulty any more. I did notice that I have a problem on keeping the drill at where it started. Even after using an auto center punch, I still drifted off center when drilling. I’m going to need more practice on this.

Dimpling/Countersinking

Dimpling is very easy with the DRDT-2. I spent a few minutes following the manual to adjust DRDT-2 with dimple dies, and after that dimpling the sheet is probably one of the easiest task in the build process(as long as I use the correct dies on the correct hole of the sheet metal)

For countersinking, since I only have one air drill, I had to remove my drill bit and switched to the countersink cage and drill. I tried a few quick burst on the trigger and it ‘s not that hard to use. For the first holes I double check the size by placing a rivet into the countersunk hole and see if the flush head is slightly below the aluminum surface, later I simply count my quick bursts on the trigger. Of course as soon as I got too confident, mistakes happened. While I use the same number of quick bursts on every hole, a few times I changed the way I held the aluminum bar, which changes the pressure I applied to it. As a result, some of the holes with greater pressure applied lost way too much metal. I was surprised to see those big holes. I’m glad that I experienced this on the practice metal I bought, not the real airplane. From then on, I tried to inspect the size of countersunk hole before the last two or three bursts on the trigger.

Squeezer

I read the manual and watched this very helpful Youtube video before using my squeezer. I was a little disappointed to learn from the manual that the $55 adjustable set holder should not be used with 3/32 rivets or dimple dies. So I’ll need to use the old way of adding washers to adjust, which is not bad at all(just felt bad of wasting $55 on the adjustable one). I used it to squeeze a few dozens rivets on my practice sheet, just to get a little familiar with holding the tool and activating the set holder.

Rivet Gun

For the remaining holes, I practiced using rivet gun and bucking bar. For some reason I seem to do better with the AN470 rivets (universal head) than the AN426 rivets(flush head). A few of the flush rivets were so badly install that I use them to practice drilling out rivets. Similar to my bad hole drilling experience, I messed up drilling out the rivets because the drill shifted off center when I started drilling, leaving some big oval shape holes when the rivets were removed. This is another area that needs improvement.