Tonight I finished countersinking the longerons. Another round of very consistent holes. One more thing I found useful was a countersink drilling table another builder had made by measuring the thickness of the skin to be mated, he came up with a range of hole sizes. This is easier to measure than the depth of a rivet in the countersunk hole.
Today I countersunk one of the longerones, which took an hour or so. First I set up my single flute countersink, and dialed it in on the drill press. With that done, I hooked up my air drill and countersunk one of parts.
I was really happy with how it worked out. The single flute is superior, and requires a lot less pressure to cut. The consistency of my holes was much better than with the 3-flute sink, and it felt easier to use for some reason.
After a lot of drilling, it was midnight and the compressor had been running almost continuously. I decided to tackle the other one tomorrow
Over the last two nights I deburred the side skins for the aft fuselage. I spent probably two hours total time, including a few minutes to remove the vinyl on the exterior side. I used an oversized drill bit to debur the holes, which I found more effective than using a countersink bit.
After several short sessions, I managed to finish riveting the bottom aft fuse skin today. I had to remove one rivet, but otherwise I’m pretty happy with how it turned out.
I started deburring the side skins tonight, and couldn’t resist a photo opportunity. I clecoed on the left skin, rolled the section upright and snapped a couple of pictures. It’s starting to look something like an airplane part now! Then I unclecoed the side and went back to deburring…
Tonight I spent about 45 minutes riveting the bottom skin to bulkheads. I set about 50 rivets, most came out well. I’ll need to drill and redo one where there is too much of a gap between the sheer clip and the j-channel. I need to clamp down the end of the clip so it doesn’t lift away when I rivet. I’m going to finish riveting then come back to it. If I can get another 2-3 hours in tomorrow and Friday, I should have this step done by the weekend. Riveting with the gun is a noisy process, so I need to be mindful of my hours.
On Sunday I dimpled the bottom skin. Yesterday I clecoed the bottom skin onto the 6, 7 and 8 bulkheads, along with j-channels and battery angles. Tonight I set a few of the rivets before running out of steam.
Dimpling the holes was easy, and I was able to get it all done on my DRDT-2 dimpler. I needed to prop up the skin a few times, but that was easily done.
Clecoing the skin to the bulkheads required two saw horses, at least 3 feet tall. Since mine were not that tall, my dad made up a pair of cradles that attach to the top of my saw horses. These worked great, and clecoing was easy.
I set a few rivets tonight. I actually squeezed several that I could reach, then made up some practice pieces and set a few rivets using my gun. Since it’s been a while since I riveted with the gun, I wanted to make sure I remembered the right settings etc. 25 PSI is plenty to set 3-3 and 3-3.5 rivets. I taped over the holes around the edges, as these are riveted later.
Not much progress this week, there has been a lot going on with the Coronavirus grinding life to a halt. Today I primed the bottom skin and j-channels, which always seems time consuming. For the first time ever, I ran out of paint before I finished, so I had to mix another batch. I applied more than I needed to on the bottom skin, but I wanted to avoid tiger stripes and have a somewhat even appearance. Not that anyone will see it, unless they are inspecting the airplane.
My biggest concern was keeping the etch from seeping through onto the outside of the bottom skin. I used enough masking tape to hopefully prevent that from happening, but I’ll give it a close inspection later. There was a tiny amount of paint overspray onto the outside skin, but that will wipe away with some acetone.
Today dad helped me rivet the bulkheads and battery angles, and then we deburred the j-channels and channels that will stiffen the skin in the aft fuselage.
We deburred all of the j-channel lengths, fairly easy with not too many complex shapes. Also started dimpling the j-channel, as seen in this picture below. In the background are more stiffeners and the bottom skin, which needs to be deburred and dimpled next.
Today my dad helped me with some countersinking and riveting, and we assembled the battery angles. We also riveted together a couple of bulkheads and dimpled the flanges.
I forgot to get a picture, but we also riveted the two bulkheads (7 and 8) together, and dimpled the flanges of both.
With help from visiting parents, I was able to prime another round of bulkhead parts today. Paint finish was ok, the only problem I ran into was failing to realize how low the pressure was getting. Not used to the new hi-flow connectors, I wasn’t paying attention to the steadily dropping air pressure as I painted. I did notice the spattering of paint, and then realized the pressure had dropped from 120 to 80 PSI. Once it built up again, it was all good.
