Dave’s RV-7A Building Log

Did battle with the paint gun. I decided to prime a practice part, the screw gauge that Van’s supplied, and the rear spar bearing. I washed the parts with Dawn, sprayed them with the cleaner/etch, let them sit a few minutes, and then scrubbed them with Scotch-brite. It worked really well, and the etch didn’t smell bad at all. I was expecting it to really stink. I then mixed up the paint. I had to thin it down a little bit with distilled water in order to get it to 20-25 seconds on the drip test. For some reason, the spray gun didn’t want to work. I messed with it for a while, but it just wasn’t spraying. I gave up and cleaned out the gun. In that process, I found out that it sprays water just fine. So I tried the paint again. This time it worked fine. I still need to perfect my painting skills. I think I got it on a little too thick at the beginning, because it kind of beaded up. Overall, the parts turned out well.

I then riveted the rear spar bearing bracket together. The pictures show a rivet in the pneumatic squeezer before and after squeezing. And then the final assembly. My first riveted part. Woohoo!

I spent the rest of the evening drilling out the right HS skeleton and clecoing together the right HS.

I really cooked through some stuff today, despite painting primer (just regular old primer–not aircraft primer) on one of the garage walls. The 50 year old wallboard was just too dingy. A coat of white paint really did wonders.

I deburred the edges of all of the ribs. I got that down to a pretty good system on the Scotch-brite wheel. Next was the fluting on the ribs so they would lay flat.

I then assembled the left HS skeleton and drilled out the holes attaching the spars and ribs together. I then put on the skin. That is way cool. It really looks like an airplane part. Even Julie and Adele were impressed.

I drilled out all of the holes for the skin, carefully lining up HS-404 and HS-405. Thanks to Phil Anderton’s site, I avoided a potential pit fall with the drilling of the HS-405 ribs. I trimmed a little too much off of the HS-404 ribs, but was able to move the holes a little bit and still maintain the correct edge spacing on the HS-404 tab.

I also drilled the remaining holes on HS-710 and 714.

I disassembled everything and prepared to attack the right side. My daughter helped me out a little bit. I’ve been having trouble finding tasks that are safe enough for her to handle at 7 years old. I gave her some clecos to take out with the pneumatic cleco tool. She handled that really well.

Spent most of the day on other projects such as building a wheeled cart for the bench-top tools (thanks to Jim Piavis for that idea) and putting in a new utility sink. I’m glad the prep work is finally coming to a close. Then I can concentrate on building the airplane.

I spent half an hour practicing countersinking on the drill press, so I wouldn’t screw it up again. It came out great this time. It still seems a bit unreliable. The depth of the four holes is slightly different, eventhough I used the same set up for each. Perhaps it depends on how much pressure you put on the countersink mechanism. I also did the required trimming on the HS-404 ribs. I used the bandsaw for rough cuts (which works very well BTW) and cleaned them up on the Scotch-brite wheel.

I got the replacement parts back to the place where I made the mistake before. I was about to push on and do the countersinking, but decided I was tired and didn’t want to make any mistakes.

Bought a cheap Delta band saw and drill press. It’s amazing what $99 (each) will buy you. These are pretty cool tools. The band saw takes a lot of set up, but works great. I used it to knock off the corners of HS-710 and 714. Saved a lot of time over sanding them off. I got an 18 tpi blade for the saw. I figured that would be better for cutting the aluminum. It cuts through just like butter.

I pondered quite a bit on how to attach the drill press, band saw, and sander to a small bench on casters. I don’t want to attach them to the bench. They’d always be in the way. And storing them underneath and lifting them up and down is already getting old.

The replacement parts from Van’s arrived already. It’s nice being within one UPS day of Van’s. I started re-doing the work on HS-702, 710, and 714 by final drilling and doing the trim work on the HS-702’s.

The sprayer and little etching pencil arrived from Harbor Freight. The etching pencil works great. That will make it easy to identify where everything goes after they get a coat of paint on them. I spent some time playing with that and setting up the sprayer. Since I plan on spraying everything outside, the weather needs to cooperate. I was going to test spray some stuff, but the wind was blowing and it was raining last night. Instead I spent a little bit of time sanding the HS rear spar doubler.

I did a little Scotchbrite work on the HS rear spar doubler. There was one spot on the surface that was particularly pitted. I tried sanding it out with the wheel. It did an acceptable job, but now the surface is uneven. I’ll end up going back over it with course/medium/fine on the palm sander. I’m basically just tinkering around waiting for the replacement parts. If it looks like they will not arrive by the weekend and the sprayer still isn’t here from Harbour Freight, I might start in on the VS.

The Scotchbrite wheel finally arrived, so I spent some time playing with that on some scrap. I also tried deburring some of the ribs with it. It works fairly well. I think because the wheel is so new, that’s it’s still fairly aggressive. Running the edge of the rib at a right angle to the wheel produces makes the edge nice and smooth but produces a bit of a burr on one side of the edge. That seems to come right off with a Scotchbrite pad. I’ll keep playing with it until I get it right.

I also spent a little bit of time sorting tools and finding new homes for things. I still need to make more room. There’s no way the HS is going to fit on the bench right now.

I spent most of the weekend at a Y Princess camp out with my daughter. I did get in a few hours on the project on Sunday afternoon, which was unfortunate as you’ll soon see…

My first major screw up. I dimpled HS-702 and countersunk HS-710 and HS-714. I made extra double sure that I was dimpling and countersinking the right side of everything. That went fine. I think my problems started with the dimpling. I think I dimpled HS-702 too much. I started with a shallow countersink and kept adding a 1/4 turn to the countersink depth each time. I got to a point where the dimple disappeared into the countersink, and that’s where I should have stopped. I could never get the skin to lay completely flat, I think because the pneumatic squeezer warped the surface of HS-702. I kept going deeper and deeper with the countersink to the point where it was obvious I had gone way too far. I could call Van’s and see if there is some work around. However, this is right at the attachment point of the HS to the fuselage. I don’t want that area comprimised in any way. At this point, it’s fairly easy to start over with a new HS-710 and HS-714. Since HS-702 is match-drilled to those pieces and I figured out that I drilled the holes past the bend when I wasn’t supposed to do that until the last step, I decided to get two new HS-702 pieces as well. So $80 and 4 hours of work wasted. Not too bad. I just need to be more careful until I get all of the tools figured out. That will be especially true when I start riveting. As things get put together, it will be more and more difficult to fix mistakes.

After that, I took it easy. I de-burred some ribs. I measured out and marked the holes for the forward end of HS-405. After the screw up, I didn’t want to make any more mistakes for the day. I spent about an hour reading through the rest of the instructions for the HS, laying out the pieces and figuring out where everything fit.

Started working on the HS front spar. Shaped the ends of the HS-710 and HS-714 reinforcement angles. I did that on the bench sander, but it would have been much quicker to do some initial cuts with a band saw. Final drilled the reinforcement angles to the spar, then bent the 6 degree bend on the ends with a vise and hand seamer. Cut the extra flange off of HS-702. I followed the directions and drilled the #30 hole then used the Unibit to make a 1/4″ hole. That worked really well. From there I used the spins. I tried to straighten out the little bit of bend that was left over. I went back to the bench sander to smooth the sharp corners on the cuts. After that I put the 6 degree bends in the ends with the vise and some blocks of wood. Then I clecoed the pieces together and read further on in the instructions.