Mar 04, 2021     One final practice kit - (1.5 hours)       Category: Practice Kit

The empennage came with a small practice kit. I was going to hide it away some day and save it as a rainy day project for the kids or for a friend. But my oldest saw it and was so excited to build it. I'm glad we did, I think it really helped to get him excited about the project overall.

He actual got to measure and mark the rivet locations, he center punched them, then drilled (with a lot of assistance). I showed him how to deburr the holes and we tried to cleco the holes but he doesn't quite have the arm strength. We're going to need to work on that forearm grip strength so I can have a real helper in the future. I took care of the rivets but he got to at least see how the squeezer worked and even the machine counter sink. He thought it was the absolute coolest thing. He calls it the “PPP” - Perfect Practice Piece - he's so proud of it.

For my benefit, it actually was good to do this last little kit. It included nut plates which I have not done to date, and I was happy that I set my squeezer perfect right off the bat. I even noticed what I believe is an error in the plans calling too long of a rivet. I made my own call on the rivet length and it came out well.

  Mar 02, 2021     Airfoil Kit #2 - Finish up - (1.5 hours)       Category: Practice Kit

Just a quick session to roll the leading edge and rivet the double flush trailing edge. Trailing edge came out very straight this time. Still had trouble rolling the leading edge without some pillowing. Maybe that is just as good as it gets. As my tech counselor reminded me - that's why they hide it where no one can see it.

After struggling with it a bit, I did get those pesky final rivets near the trailing edge of the ribs bucked. I ended up taping my skinny bar to the tungsten bar, and they bucked pretty easily actually.

Got everything cleaned up and ready - tail kit comes tomorrow!

  Mar 01, 2021     Airfoil kit #2 - continued - (2.5 hours)       Category: Practice Kit

With parts primed, I was able to proceed with the dimpling and final assembly of the second airfoil kit. I'm very happy with how this one is going. I do need a little more practice with back riveting; I feel like I'm not getting square on the rivet shank. Several were bad and had to drill out. Even used my oops rivets on several, but those worked well.

I'm very happy with the flush rivets that I had to buck. They all sat nice and flat. Just the trailing edge wedge and leading edge roll left.

I had some urgency to finish the practice kit today because the empennage should be here in two days!

  Feb 26, 2021     Airfoil Kit #2 - (2.0 hours) Category: Practice Kit

Got a big haul from Fedex yesterday. My primer from Sterwart Systems came in and also my 2nd airfoil practice kit from Vans. I started on the practice kit and got all of the parts deburred and fabricated the skin stiffeners. So much easier the 2nd time. Just nice to be able to confidently progress the work without second guessing every step of the way. Cleco, match drill, move clecos, drill more, disassemble, debur, reassemble, repeat... Starting to get into a groove.

Really tried to focus on getting the trailing edge wedge correct this time. It's not possible to have both skins completely cleco'd to the skeleton and also set the trailing edge flat against the bench. My method was to cleco top and bottom skins to make sure everything was aligned, install the trailing edge wedge between the skins, and then use vice grip clamps to hold the trailing edge in alignment. Then I removed the clecos from the bottom skin so that it could sit flat on the bench with the trailing edge clamps just overhanging. Then I drilled the holes. I think it came out a lot better - we'll see how it goes after dimpling and countersinking. For now, I'm happy with it.

Everything is ready to prime, but the weather is crap this weekend. Since I'm really wanting to test out the primer, I should wait for better conditions.

Got another treat in the mail yesterday too. I know at some point in the future I'll need a pair of safety wire pliers. My brother is an A&P and I figured before I buy some I should at least ask him if he has an old pair laying around. I texted him to ask, and he said he actually had a nice pair of Bluepoints that I could borrow. Then I got a text 10 minutes later saying pliers are on their way. I was so surprised that he had gone out and shipped these pliers to me. Well yesterday it all made sense when I received an amazon package with a pair of brand new Milbar safety wire pliers. What a nice gift. He said he didn't want me using the cheap ones. Thanks Bro!

  Feb 10, 2021     Practice Kit - Airfoil (Cont.) - (4 hours)       Category: Practice Kit

DRDT2 arrived so I was able to dimple the skins and start rivetting. Back-rivetting the -3's was pretty easy although I have a tendency to overdrive them. Doesn't take much for -3's. I bucked all of the rivets to the spar and they mostly turned out good. I wanted to meet with my tech councelor this weekend, but it's going to be in the teens and 20's. I'm going to send him some photos and see if he can give any pointers. [He gave a thumbs up!]

I proceeded to the trailing edge and the double-flush rivets. Not very good. First off, I think I had the trailing edge wedge a little too close to the edge when I drilled it. I think these come pre-drilled in the actual kit so hopefully that takes out some of the guesswork. Also, didn't use the double-sided tape or proseal method so tough to keep straight and try to back-rivet while still cleco'd.

Lastly, I rolled the leading edge. I thought that didn't turn out too bad until I realized that I did not run the edge roller tool on the top skin prior to rolling. That made it almost impossible and I was trying to hold the skins open by hand. Then overdid the edge rolling in places and just really deformed the edge. Once rivetted, it was as expected and looking terrible. Really seems like there should be double the number of pop rivets on the leading edge; the spacing is really wide between them. I recognize they are not really structural, but it's tough to keep the skins in contact with so much space between rivets. Really need to practice edge rolling and remember to do that prior to rolling the skin, or dimpling.

Anyways, I think this one is done. I just ordered another practice kit.

Purchases: Shot bags, HF spray gun, clamps, misc tools, Van's Practice Kit

  Feb 05, 2021     Practice Kit - Airfoil - (3.0 hours)       Category: Practice Kit

Everything on the airfoil kit has been pretty straightforward so far. I have all of the skeleton done and the skins are drilled, but I'm at a stopping point until the DRDT-2 arrives and I can dimple the skins. Only potential challenges so far were drilling the trailing edge and dimpling the last couple holes on the ribs. I made drill guide from a scrap piece of oak that worked fine for the trailing edge. I was able to make the special dimpling/bucking bar for the last few rivets and found I could actually put a pretty good dimple in the rib by clamping the bucking bar to the bench and hitting the dimple die with the flush set gun. I did pick up a nice back rivet plate from a local metal supplier, but won't do much with it until dimpling is done. I need some more scrap aluminum for practice.

In my downtime I decided to test some self etch primer. Based on the forums, it seems SEM is the best but $20+ per can and nobody seems to have it. The duplicolor seems preferable over rustoleum and according to the autoparts store website, I thought they had it in stock. When I got there all they had was the rustoleum self-etch so I bought it. I prepped parts several different ways: no scuff with just acetone wipe, wet scrub with soapy scotchbrite pad plus acetone, dry scotchbrite scuff using power sander and acetone wipe, 400 wet sand and acetone wipe. I honestly can't tell the difference between any of the preps and I'm a little disappointed with the product. It holds well and doesn't come off with a tape test, but it scratches very easily with a fingernail and light pressure. And acetone takes it off just by looking at it. I'm going to see if it gets better after a few days of "cure" although the directions on the can don't mention anything about full cure time. I went ahead and ordered some Ekoprime to test that out - hopefully it is better. I think it will be less expensive overall considering that I plan to prime full inside. Going to SEM rattle cans would get expensive, but I suppose not in the grand scheme.

I also redid the flush rivets on the one end of the toolbox. They look much worse than they did before. I think a couple just aren't sitting straight. I may have mangled those holes a bit when I drilled the rivets out. Those rivets also weren't meant to be -4's in the first place so maybe they were doomed to fail.

Purchases: Primer

  Feb 01, 2021     More Practice - (2 hours)       Category: Practice Kit

The airfoil practice kit arrived. I'm not going to get very far on that until my dimpler arrives. I did make the cuts on the stiffeners - started with snips, but quickly move to the band saw - much easier.
The extra rivets for the toolbox have not showed up yet, but I harvested a few from the airfoil to finish the tool box. Still need to redo some rivets. I'm now suspecting that the dimples for the -4's on the ends are not deep enough.

Airfoil kit also came with a miscellaneous assembly of a couple plates and an angle. It involved countersinking for a -4 in the angle. I thought I did a good job on the countersinking and adjusted the depth several times until the dimple sat flush, but when I rivetted it together, there seems to be a gap on the backside of the angle. I suspected maybe a burr on the countersink, so I drilled it out and re-did it. Still a gap - might just be a slight bend of the plate. I did practice the edge roller and the two lapped plates turned our really well. Using the squeezer up against the back of the angle is tight and I ended up with some marks on the angle; I need to confirm if these would be acceptable or not on the airplane. Will need to be more careful with that.

Overall, very pleased with the rivets though. I bucked all of them instead of the squeezer. The -4's into the angle might need to be countersunk a little deeper. I did set the rivet flush in the hole then added .007" per Section 5; still need to play with that I guess. Seems like it would vary based on the thickness of the skin.

I ordered a back-rivet plate from a local steel supplier too.

Random primer thought - I think I'm leaning toward full skin prime so probably Ekoprime.

Purchases: Back-Rivet Plate Metal4u.com

  Jan 30, 2021     Practice Kit - Tool Box - (4.0 hours)       Category: Practice Kit

Got to work on the practice kit and do some actual drilling, dimpling and riveting. My first rivets ever. Got every thing deburred and cleco'd the ends on the box, and then immediately made a big mistake. The ends are supposed to be 3/32" (-3) rivets - that registered clearly in my head that those are the smaller rivets and I instinctively grabbed the #30 drill bit. After match drilling half the holes on both ends, I moved the 3/32 clecos over and immediately knew I screwed up. #30 bit is for the 1/8" (-4) rivets. Oh well, that's why it's a practice kit. I just proceeded to drill them all to #30 and used the AN426-4 flush rivets that were provided with the kit. If it were the actual airplane I would have stopped and at least checked the edge clearances for the larger rivets.

My DRDT-2 isn't here yet so I used the squeezer to dimple to the box and the ends. Piece of cake. Then re-cleco'd and started driving flush rivets with the squeezer. That squeezer is way too easy; pretty much all perfect right off the bat. The squeezer won't reach the line of rivets across the bottom so I used the gun and the tungsten bar. Still pretty easy because I had the bottom of the box to rest the bar against and keep it square. Most turned out pretty good and no damage to the skins; I used blue painters tape on the flush set, but also did some without it and really didn't note any difference.

The rivets along the front edge of the box are AN470's with the button head. I used the squeezer on the first few. Again, couldn't be easier so I moved over the gun and bucking bar for the rest. This time I didn't have anything to support the bar against so it was a little more challenging. I got my first smiley too. Then another.

The most challenging rivets were the for AN470's on top that hold the handle. The box top is an awkward shape and hard to support while driving with the gun and bar. All four turned out bad. Got good practice drilling them out. Second attempt a little better, but still drilled out two of them. Third attempt was passable, but still probably the worst of the rivets I did today. Following the recommendation of other builders, I'll probably drill out all of the rivets and redo them just for the practice. Ordered some extra rivets from Aircraftspruce, including the replacements for the -4's I borrowed for the end skins. I can see a lot of time in my future waiting on parts or tools.

I also worked on a rib flange bender this week and finished it this morning. I know I don't need this for a while, if at all, but I saw it on the forums and realized I had most of the parts. I was just itching to fabricate something with all of my new tools. Came out pretty nice; can't wait to use it.

Lessons Learned:
- read the notes, slow down, read it again, before you drill, read it again, before you dimple, make sure it's the right side
- Use the squeezer whenever possible
- Running the rivet gun at about 50psi on the regulator. After setting the regulator, run the gun, then set it again. The pressure drops significantly after the first use of the tools.
- My 18v electric drill seems to run higher rpm than the air drill - might need to increase the pressure on the drill. I was running it at 90psi. Electric drill is definitely an option.
- Find a way to support the work when using the gun. It will move around on you.
- Instinct is to put a cleco in the corner of a plate. When doing this the first rivet is away from the corner and tends to curl the plate up. Better to cleco the second hole so that the first actual rivet goes in the corner.
- This is going to be fun. I'm really enjoying having a metal shop.

Purchases: HF airhoses & accessories, ACS Rivets