Started off the day dimpling the vertical stabilizer skin with the DRDT-2. I’m pleased with this tool. Dimpling large parts like the skins is a piece of cake and the dimples are consistent. I will say that I am considering getting a c-frame as well. It would have come in handy for riveting the rear spar. Juggling the spar and the pneumatic squeezer was challenging. While the squeezer was workable, I think the c-frame would have been easier.
Once the skins were complete, the fun began! I was dimpling the substructure when I decided that the VS-707 rib needed an extra hole. So I made one. With the pneumatic squeezer and dimple dies. I hammered out the unwanted dimple and made a doubler to fix the flange. I completed the rest of the dimpling uneventfully.
I riveted the aft spar assembly together. This went well and I’m happy with the result.
I riveted the front spar doubler to the front spar and clecoed the ribs to the front spar in preparation for riveting. And that’s when things went south again. I tried to rivet the root rib and the nose rib to the spar from the front of the spar to the back. Turns out that this is extremely difficult due to the angle of the nose rib. Even with an offset rivet set in the gun, I couldn’t get straight on the rivet. I tried to buck it anyway. The rivet folded over. The angle of the nose rib made drilling out the rivet problematic as well. I thought about drilling the shop head but it was too messed up to drill. I ended up mangling the hole beyond repair. Turned all three parts into scrap. I ordered replacements from Van’s and since I was already going through the process and paying for shipping I included a replacement VS-707 as well.
Lesson Learned: If it doesn’t seem right, stop and think about it. When I couldn’t get the rivet set square to the rivet, I should have stopped and considered shooting the rivet from the other side.
I’ll be honest. I was dreading this step. I had never sprayed anything before. Turned out to be not nearly as bad as I thought. I didn’t get get pics of the process. Maybe next time.
My first attempt was on the practice project. Took a while to figure out how to get the gun set up. Shot way too heavy on the practice project. You can see how much darker those pieces are than the actual plane parts. I got it dialed in and I am happy with the result on the plane parts. They almost look like they’ve been anodized. They’re just a little darker and duller than bare metal.
The gun I used is a cheap touch-up hvlp gun from Harbor Freight. It’s perfect for the smaller parts and acceptable for the skins. I went with a narrow fan about 8 to 10 inches from the work with 30-40 lbs at the gun. I wiped everything down with lacquer thinner before I shot the primer. I mixed the P60G2 1-to-1.5 with the R7K44 reducer per the data sheet from Sherwin-Williams. The P60G2 was way more goopy than I expected. I was thinking it would be like paint. It was actually thicker and stickier. I wore a Tyvek suit, a 3M respirator, safety glasses, and nitrile gloves.
I bought an empty paint can at home depot that I am using to store and properly dispose of left over paint and solvent. I ran lacquer thinner through the gun and right into the can to clean up. It took about two ounces until it ran clear.
I’ve been using a single flute de-burring bit in my drill on the low speed setting to deburr all the holes. It seems to work pretty well. I hit it with about two turns and light pressure. That leaves a nice clean finish without enlarging the hole or leaving a visible chamfer.
Today I dispelled the notion that this airplane is going to be perfect. I was trying to de-burr the edges of the skin on the scotch bright wheel and accidentally touched the other side of the skin to the grinding wheel. It hit the top corner of the skin and bent it a bit and took a nick out of the edge. I was able to straighten it. It was only bent a few degrees. I was also able to file the nick out of the edge. Probably not the worst mistake I’ll make. It only cost me about ten minutes.
I picked up a bit extension from home depot yesterday so that I could use the de-burring bit on the insides of the flanges. This kept the bit sufficiently straight and produced an acceptable result.
Used a maroon scotch bright pad and scuffed everything up. Ready for priming.
We had help from my brother-in-law, John O’Brien today. Lot’s of fun building with family! We cleco’d the skin to the substructure, match drilled all the #40 holes, disassembled everything, and peeled the blue plastic from the rivet lines on the skins with a soldering iron that I blunted on the bench grinder.
I didn’t get to shoot primer on the practice project today. I had to work and then brine the turkey for thanksgiving. There wasn’t enough daylight left after all of that. So instead we decided to actually start work on the airplane this evening. I’ll spray primer on the practice project and the vertical stabilizer all together this weekend.
I clamped and drilled the trailing edge wedge. Then I disassembled everything, machine countersunk the wedge, and scuffed all the substructure parts and the inside of the skins in preparation for priming. Next we’ll clean up the surfaces with some lacquer thinner and shoot the primer and then dimple and rivet everything together.