So, we picked up a 4″ no-hole yoke from Avery Tools, and with this we were able to squeeze those tight-quarters rivet placements. And if the photo below were at all legible, and/or there wasn’t a bookshelf in the way, you’d see that, yes, we do in fact have a set of completed tail feathers.

We then jumped right into riveting the stiffeners to the rudder skin, since Dad had spent the last several weeks doing the trimming, drilling, dimpling, deburring of the rudder components. We used the C-frame backriveting technique for most of this job, but found that is was not quite as foolproof as we would have liked — we still ended up with some clubbed rivets.

We’ve since decided that the thin skins of the moveable surfaces, coupled with #40 holes and dimples, cause the rivets to move around a little too much in their holes, resulting in some of them bending over while driving. We might try a slightly smaller drill bit (#41?) next time.

We then moved on to bending the rudder trailing edge with the great 2×8 press brake that Dad fabricated (I’ll get some pictures of that process when we do the elevators), and we were pleasantly surprised with the results. Following the advice of several other builders, we taped a wooden dowel to the inside of the trailing edge to ensure that we got the proper bend radius.

Finally, we assembled and drilled the rudder understructure, and prepped the parts for priming.

Of course, no airplane work session can be without its pitfalls and heartbreak, and this one was no different. While match drilling the rudder understructure, we noticed that we’d over-trimmed the R-710 rudder horn brace, pictured above. This caused our drilled holes to be too close to the top edge (the bottom edge in the picture) to meet minimum edge distance requirements for a 3/32 rivet.

After much debate and hand-wringing, we decided to order a replacement part, and we moved on to priming and riveting what we could of the rudder skeleton.

Oh yeah, and last but not least, here’s a picture of me, doing … something.

For some reason, while using the Cleaveland squeezer, we ended up with some “clubbed” shop heads, illustrated below from MIL-R-47196A, the military specifications for driven rivets.

Although we carefully aligned the flush sets of the squeezer, and watched the shop heads as they formed, the fact that these rivets had “dumped over” escaped our attention until we took a closer look. Some example photographs are included below.

With the tiny AN426AD3-3.5 rivets, it’s difficult to get a properly-sized shop head that adequately covers all of the drilled hole beneath it. If we moved the set or bucking bar just a little off center, we got results like these. We found we had a much easier time forming acceptable shop heads with the bucking bar rather than with the hand squeezer.

At this point, we’re still not comfortable using the squeezer without it being solidly mounted to the workbench.

We called our Tech Counselor, Tom, and he graciously agreed to return just a few days after his first visit, to confirm our suspicions that these rivets needed to be replaced. Before his arrival, I carefully inspected each accessible shop head with a flashlight, then marked any suspect rivet with a permanent marker.

Tom agreed that some of the clubbed rivets would need to be replaced, but also added that the odd rivet here or there with an imperfect shop head might be considered acceptable, while several bad ones in a row should be drilled. We’re still developing our own sense of quality workmanship, so Tom’s advice was again invaluable. Thanks again, Tom!

So, after completing the vertical stab, we went back to the HS, and spent a couple of hours drilling out and replacing rivets. We got fairly adept at the process, and won’t have any reservations about replacing bad rivets in the future.

The good news, however, is that the horizontal stab is now done! Both the HS and the VS are now in temporary storage, as we move on to the empennage control surfaces.

The first order of business was to have our progress and skills reviewed by an EAA Technical Counselor. A tech counselor is an experienced builder or mechanic who volunteers his time to help newbies such as ourselves with the inevitable problems and questions that crop up during the build. So last night Dad and I hosted Tom Olson of EAA Chapter 33, and he gave our work a thorough inspection.

Happily, Tom seemed pleased with the quality of our work, and we spent a couple of hours chatting about tools, techniques, components, and those amazing flying machines called RVs. Tom’s endorsement really boosted our confidence, and we hope to see him at regular intervals as the project continues. Thanks, Tom!

This morning we set up the shop to continue where we’d left off, which was on the left half of the stab, with only the HS-707 nose rib riveted in place. We began by riveting the forward spar assembly to the HS-706 and HS-708 ribs, and then we got busy putting the skin on.

As many others have mentioned before, a tungsten bucking bar is worth its weight in gold, and after today, I’d have to agree. This little baby fits into all kinds of hard-to-reach corners, and it’s so dense that you really only need to have a couple of fingers holding it to get a good shop head on the rivet. I’ll stand by what I’ve said many times in the past: Good tools make all the difference.

Dad and I worked all morning, and developed a good rhythm between shooter and bucker. Good communication and a steady rhythm seem to be the key to setting perfect rivets. We set 200 rivets today and didn’t drill out a single one. Good stuff.

In just a few hours, we managed to finish all of the bucked rivets on the interior of the stab, so all that’s left for tomorrow will be squeezing the edge rivets with the hand squeezer. Almost there!

Riveting began by wrestling the HS-707 nose rib into place on the left skin. This baby does not want to squeeze its way forward very easily, and takes some muscle to get the skin into position over the holes. Then, once it’s finally in place, the forward nose of the rib doesn’t like to “sit down” on the skin. We had put a flew clecoes in the bottom side of the rib as well, just to hold things together while riveting the top side.

This was our first real test of riveting skin to ribs since completing the Van’s airfoil practice kit. We set the air compressor output to roughly 38 psi, and adjusted slightly down from there with the Brown Tool swivel regulator on the gun. We also followed the advice of several builders on the VAF Forums, and covered the factory head and surrounding skin with a couple short strips of masking tape to help eliminate slippage and scratching from the flush rivet set.

Everything worked beautifully. I think we may have drilled out one rivet with a malformed shop head due to lifting the bucking bar off the rivet too early, but other than that I think our confidence and skill are definitely improving. Oh, and we’re also getting pretty good at drilling out rivets.

Then, while moving things around in preparation for the next few steps, we dropped the rear spar assembly, causing one of the HS-603s to bend about 20° toward the flanges, just outboard of the ends of the riveted HS-609s.

Using the hand seamer, we were able to mostly straighten it back out, but there are still some damaged areas visible from the bend line. I was concerned that we may have caused unseen structural damage, so I decided to email some photos to Van’s.

Several hours later, Van’s Aircraft builder support rep Ken Scott returned my email, with this reassuring statement:

Probably not any disaster. Certainly the fix is straight enough to use. There’s no way of knowing what the future holds, but it seems unlikely that there will be problems. If that’s not enough reassurance, simply taking the spar apart and installing a couple of new HS-603s will eliminate all uncertainty. It might add a day’s work to your airplane project …

So we decided to at least cleco the spar to the ribs and skin, to see if we could salvage the part.

We got everything to align fairly well, and the damage seems minor, so at this point I think we’ve decided to “build on” after a brief hiatus. The right side of the rear spar on the stab will just have to be a place we keep our eye on down the road for any abnormalities.

I’m sure this little catastrophe is only the first of many to come.

The squeezer yoke bench mount and Cleaveland Main Squeeze made setting the -4 rivets a breeze — or, at least, as breezy as manual squeezing can get.

Van’s rivet callouts for this section are just a hair too short, but the instructions are adamant that you stick with what’s called for, so we ended up with shop heads that were just a bit too small, but adequate.

We had trouble getting the squeezer yoke over the HS-814 angle, so we ended up breaking out the gun and bucking bar. Yep, we had to drill out a couple of rivets as a result.

Things look pretty scratched up, but close enough for government work. (I hope.)

Several weeks ago, we finally found a decent used compressor on Craigslist, a shiny Craftsman 30-gallon oil-less 120V portable, complete with a regulator and 50 feet of hose. Everything you’ve read about oil-less compressors is true: this thing is excruciatingly loud, deafening, almost maddening. There is simply no way I could tolerate standing next to this thing in the shop. That’s why we keep it in the garage, and feed the air hose through the wall and down into the basement shop, where you hardly notice the sound at all. A very impressive solution on Dad’s part. On the plus side, however, 30 gallons is just about the right tank size to keep the pump motor from running constantly, and only a long bout of drilling or riveting will cause it to start again. The tank fills to about 120psi from empty in under ten minutes.

Dad and I picked up an air line filter and a few 1/4″ fittings from Home Depot, and we were ready to fire up the Sioux air tools. The drill and rivet gun roared to life. For a while we tried using them with an inline oiler, but this tended to get messy and over-oil the tools, especially the drill, which started spitting atomized oil from its air outlet port. I still haven’t decided whether or not to keep this in the system or just put a drop or two in the tools each day.

Once the air system was plumbed and operating, we began work on Van’s RV Training Project practice kit. I’d already built one of these things at the SportAir Workshop I attended in early May, but I thought it would worthwhile to work on another one with my own tools, both to refresh my memory and to get Dad up to speed on the basics.

The big hit during construction of the practice kit was the Cleaveland C-frame dimpler. We used this for both dimpling and backriveting whenever possible. The C-frame backriveting technique is simply foolproof, and we really felt like we knew what we were doing from the very beginning.

We did run into a few snags while working out the kinks of the practice kit, but overall I felt our skills had improved and the finished product, while maybe not completely airworthy, was definitely a step in the right direction. On to the empennage!

EAA Hints for Homebuilders: Riveting with a C-Frame

EAA SportAir instructor Wally Anderson demonstrates a backriveting technique using a C-Frame Bench Riveting Tool and a 12″ backrivet set, both from Cleaveland Aircraft Tool in Boone, Iowa. This technique seems virtually foolproof, and the results are sharp and consistent. I think I’ve just decided which C-Frame to buy.

EAA Hints for Homebuilders: Rivets 101

In this segment of EAA’s “Hints for Homebuilders” series of instructional videos, Tech Counselor Jack Dueck reviews the basics of driven rivets.

EAA SportAir Workshop, Oshkosh

I’ve just completed Day One of the EAA’s Van’s RV Aircraft Assembly SportAir Workshop, held at EAA’s immaculate headquarters in Oshkosh, WI. So far, it’s been a fantastic experience, with plenty of one-on-one help available, since class size is limited to sixteen.

The morning began at 8:00am with a classroom discussion covering the building process, tools, workspace, materials and processes, peppered with lots of specific questions from the peanut gallery.

Since there just isn’t enough time in one weekend to address everything involved in building a kitplane, the focus quickly shifted to the specifics of the project du jour–a miniature wing section (provided by Van’s)–and the required skills to slam it all together before time runs out on Sunday.

After a quick break for lunch, we moved into the well-appointed shop across the hall, and began learning our new skills. Before starting the wing section, we practiced by joining two small sections of aluminum skin together, and then riveting them to a piece of angle. No prep work had been done, so we had to measure, lay out and properly space the rivets, drill, deburr, dimple, countersink, cleco, and then squeeze, buck and backrivet the stuff together.

It was great to finally get the feel for the specialty tools like the air drill (awesome), the cleco pliers, the C-frame dimpler, the deburring tools, the 2X rivet gun and sets (backriveting ROCKS), and the rivet squeezer (buy a pneumatic one!). All in all, it was a nice, no-pressure way of getting a feel for all the basics.

We then took these new skills and began to apply them to the wing section, which required a more careful reading of schematics, as well as the new skill of trimming with the aluminum shears. We got about 1/3 of the way through this mini-project when time ran out for the day, at which point my body was definitely ready to be horizontal.

Four Methods of Flush Riveting

I recently stumbled across this old Lockheed/Walt Disney Industrial Training animation which demonstrates four common methods of flush riveting used in aircraft construction. It reminded me of those tedious film strips we used to watch in fourth-grade science class. But hey, guess what? I learned something.