The threat of rain

Saturday morning and the immense lawn of my palatial estate requires mowing. Again. Seriously, in my opinion grass is nothing more than the weed that had the best PR department when suitable lawn coverings were being decided. But, the threat of rain! Granted, it was about the same level of threat as a Chihuahua giving you an irritated glance, but I latched onto it like Wile E. Coyote when a new Acme Products catalog shows up in his mailbox. No mowing today, might as well head down the shop!

Having deferred the installation of the last two baggage floor supporting riblets the last time around, I knocked those out pretty quickly. With those in place along with all of the other ribs that will support the baggage floors, it's not surprising that the next step is to rivet the baggage floors onto those ribs. A few different rivets get used; the first are regular LP4-3 blind rivets which go into all of the undimpled #30 holes in the baggage floors. I clecoed about half of the holes and pre-placed rivets in the rest.



The next set of rivets are flush blind rivets - those go into all of the dimpled #30 holes. I chose to do the ones that are in the same row as the non-dimpled holes first.



That just left the holes that run along the tunnel section. I used the silver clecos in the #40 holes since there are only three of the #30 holes and the baggage floor skin was curling away from the baggage rib flanges. I needed a bit more than the one or two #30 clecos I would have been able to use.



I think the most defining factor of the work I've been doing lately is installing nutplates. It seems that every other step involves dimpling and installing nutplates. And the K1000-08 nutplate in particular has achieved a level of ubiquity rivaled only by GEICO commercials. That's why it came as somewhat of a surprise to notice (and I'm glad I noticed! This would have been very easy to miss) that this particular batch of nutplates was comprised of two variants.



The blue indicates K1100-08 while the red shows K1000-08. The numbers are so visually similar that it would be easy to miss the distinction. Conversely, the rivets themselves are quite distinct.



The K1000-08 is on the left. The K1100-08 on the right will be used in the holes under the right side baggage floor. As I've surmised before, those holes will eventually be home to screws that will sit flush to the floor to make room for the fuel tank.

With the rivets selected and positioned near their ultimate resting places, all that was left to figure out was how exactly some of the nutplates were to be put in position, considering that access to the holes was blocked on all sides by the bulkhead and floors. See the back row of nutplate holes and how there's no access to the bottom of the baggage floors? Yeah. Bummer, that.



The trick is to flip the whole assembly up onto its side and install them from the bottom.



Note how I managed to focus the camera on my emerging bald spot instead of on the nutplate I was clecoing into place. Nice. I'd have been better off mowing.

With one cleco in each of the rivet holes, it easy to rivet them into place. Note that these are the CSR flush blind rivets, not the normal LP4-3 blind rivets.



The remaining four nutplates were accessible from the sides of the floors, so they were installed with the normal AN4263-3.5 flush rivets and the rivet squeezer. Once those were done, I wiped the whole deal down with MEK to remove the Sharpie writing and my grubby paw prints.





So, do you remember those bearing brackets that I put together last time? The ones with the gap between the plates that I was worried about? The ones that I was wondering why I was putting together at that stage in the first place? Well, here we go. The next step is to install a plate between two of the floor riblets to provide support for them.



This was another of those cases where it was going to be easier to get at the riveting by flipping the whole thing over and coming at it from the bottom.



Having grown accustomed to working inside these parts to rivet through the flanges, I just automatically bend the rivets and grab the little close-quarters wedge thingy right away. Doing it that way helps get sufficient clearance to get the rivet puller down in there. This is probably the best picture I've been able to get that shows what a difference the wedge thingy makes.



The bearing assemblies go in with the heads of the flush rivets up against the skin. That shouldn't surprise anyone - can you imagine how poorly it would fit the other way around? Here's some good news: look at how the cleco in the back pulls the plates of the bearing assembly together! I was worried that the gap between them was going to be a problem. It looks like it won't! Unfortunately, having that cleco there made the rivet inaccessible enough that I had to use the wedge thingy again, and it is the wedge thingy that I blame for this:



Can you see the part of the mandrel sticking out? It seems to have broken in a different spot, probably because of the way it got pulled when I used the wedge. I doubt that it would have made any difference to just leave it that way, but I thought it would be easy enough to file away that I might as well take a couple of minutes to do it.



Ok, everyone that thinks filing that mandrel off with a tiny little file was likely to be really, really boring and take way too much effort, raise their hand.

[My hand is raised.]

I quickly tired of it and found a faster way.



I swear, if the Roman Empire had had Dremel tools and duct tape, it would never have fallen. There's nothing they can't do!

It cleaned up right purty, iffn' I does say so myself.



There was only one more little thing to do on the page, so even though I was ready for a break (I have this little known malady called "coffee hands," the primary symptom of which is a rapid decrease in manual dexterity as my morning caffeine jolt reaches its second half-life) I decided to get it done. It's basically "go find three parts on the shelf, band saw one of them into two parts, and rivet it all together."

Voila! We'll figure out what it's intended to do next time.



Here's where we are so far:

Back on track

I was able to go visit the almost-done RV-12 to check the fit of the semi-circular wing spar tab receptacles today. Normally it would be somewhat of a burden to ask a guy to remove the wings from a plane that is nearly complete and ready for its airworthiness inspection but in this case one of them had to come off anyway. It's kind of a sad story, really. He and a friend had moved the plane to his hangar and were reassembling it when a gust of wind grabbed the right wing off of the trailer and threw it against some immovable objects. The net result is that he will have to strip off and replace the skins of the damaged wing, along with at least one of the inner ribs.

The only thing I could think to say was "at least it wasn't painted yet."

I'm not particularly adept in situations of personal loss.

Thankfully I did have sufficient tact to refrain from pointing out the benefits to me from his misfortune. So there is that.

It was interesting to be involved in removing a wing, and I have to say that it is every bit as easy as advertised. Remove the pins, pull the wing out, and ensure there is someone on the root end to catch it as it comes out of the plane. Not necessarily in that order. In fact, the third step works better as the second step. Just, you know, for future reference.

With the wing off, I test fitted the semi-circular wing spar tab receptacle to the aft wing spar tab. It fit like a glove. Now, I could have stopped there and simply assumed that the left would fit as well, but... I'm losing enough sleep over this thing already and don't need to add new chapters to the horror novel that is on my current stuff-to-worry-about-at-three-AM shelf. And really, the wing would only need to come out a few inches - what's the big deal?

Well, it's not a herculean effort by any stretch and I'm sure it gets easier with practice, but it is inarguably harder to put the wing back in than it is to take it out. Lesson learned. Naturally after all that effort, the left receptacle fit just as well as the right. Neither will need any filing or trimming at all.

Oh, and I got to sit inside a nearly-finished RV-12 too. I liked it! It's wider and seemed to have a more comfortable seating position than the RV-6. The visibility is great and the control stick falls readily to hand. I will have to adjust to the new throttle location, but that's a nit.

Now that I'm sure the receptacles are ready to be installed I can finish up the aft bulkhead on the center section. That's a simple matter of riveting the receptacles into place with a few handfuls of LP4-5 blind rivets. Interestingly, this is the first time the manual has asked that all of the rivets be put in place before driving any of them; the work of holding the parts together and in alignment is normally left to the venerable clecos.



Bada, bing, and boom. All done.



In what appears to be a pretty random ordering of steps, I then was tasked with assembling a pair of aileron hinge brackets. The four parts used to make two brackets are completely identical, a situation that I have learned requires caution. In this case, it would be very easy to countersink all four of the bracket sides, but only two of the parts need it. The other two sides will have the non-flush shop head on them. The plans clearly state this, of course, but I still caught myself thinking that I'd be countersinking both sides of the brackets. Taking a breath to think things through saved me from that. As a reminder, I marked the holes that I would countersink.



Once the parts were clecoed together, I saw a potential problem: there was a notable gap at the ends of the brackets where the bearings were inserted. I put a clamp on one of them and it closed the gap down, so the problem wasn't a mis-fit of the bearings. I figured I'd just leave the clamp on while I did the riveting to keep the parts tight.





Which worked, more or less. Now there's a gap at the other end. I suspect that I've only managed to kick that can down the road. There's nothing I can do about it now. I'll just have to burn that bridge when I get to it.



With that diversion out of the way, it was back to getting the aft bulkhead attached. This was another step that had a potential pitfall in it that I successfully circumnavigated. At first glance, it would appear that all six of the ribs get riveted directly to the aft bulkhead, but a closer reading shows that the first step only involves the two outer most ribs on both sides. The innermost ribs get riveted on the next step after having a couple more little ribs put in place. I went ahead and clecoed those little riblets into place so I so I wouldn't forget and rivet the inner ribs prematurely.





It turned out to be a better position for the riveting over on the saw horses rather than on the work bench. I'm going to miss being able to move this thing around easily when it gets bigger.



As long as I was riveting, I went ahead and riveted the riblets too. Those rivets were down in the flanges and pretty hard to get at, but the articulated rivet puller made it possible. This seemed like a great time to quit for the night. Have you noticed the way that I'm humped over in every picture of myself that I put up on this blog? It's not because I'm bending over the work; I think my back is taking a permanent set from all of this riveting and stuff.



It doesn't look like much, does it? Just to give you an idea of where this will eventually end up:

Make work

I should be able to get the wing tab receptacles taken care of tomorrow. There is an RV-12 nearing completion not too far from here and I've arranged to go use its wing spar tabs to check the fit of the receptacles.

In the meantime I did a little prep work on some of the other parts that will get attached to the F-1206 bulkhead that the receptacles will be attached to. There was also a little dimpling to be done on the top of the bulkhead. It needed to be dimpled to match the dimples in the baggage floors. There were quite a few of those, but there were also holes that should not be dimpled, and to add to the complexity, the sets were not symmetrical. I took the easy way out: I placed the bulkhead into position on the baggage floors and circled the holes that should be dimpled and X-ed the holes that shouldn't.



There are four more baggage ribs that needed to be deburred, dimpled, and have nutplates installed. I knocked that out pretty quickly.



The next step is to rivet the bulkhead and ribs onto the center section, but I can't do that until the receptacles are trimmed/fitted and riveted into place. It was a good stopping point anyway as my brain was starting to send shut-down signals after a long day at work.

Wing? What wing??

I'm being disingenuous. I knew this step was coming, although in my defense I didn't find out about it until it was too late.

But before we get to that, there's the little matter of twelve nutplates to install. At least it turned out to be twelve; I had another of those cases where I just think too hard about the situation at hand.



It sounds easy enough: "Dimple the nutplates depicted in Figure 2." The drawing points directly at them. Well, half of them anyway, but it's a symmetrical job and it's easy enough to understand. For some reason, though, I thought that the holes for nutplates on the outer edges of the baggage floors were included in this step, but no nutplate size(s) or arrows pointing at them were in evidence on the page. It was the further instruction to "then rivet them to F-1221-L & -R Baggage Ribs and F-1224-L & -R Baggage Floors" that made me think those were included. When I run into questions like this, I just read ahead a few more pages to see if the parts in question get installed in a later step. I didn't need to go far - it's on the next page.

Yes, I know: you're supposed to read ahead anyway. I do, but not to the level of every single rivet and nutplate.

So, that was solved and it was a simple matter to cleco the nutplates in.



Easy, except....

I couldn't help noticing the uncomfortably close proximity of two of the nutplates to the bulkhead.



See that rivet hole between the cleco and the bulkhead? Pop quiz: how fun is that going to be to get at with the rivet squeezer? You know those things that give you a sinking feeling of dread in your stomach because you just know they're going to be a real ordeal but then they unexpectedly turn out to be pretty easy? You do?

Good.

This was one of them. It turned out to be just as easy to squeeze as all of the other rivets.





The center section gets set aside for a little while in order to prep a couple of parts. These are going to be part of the semi-circular receptacle that a tab on each aft spar of the wings slots into, presumably to provide alignment and a little more stability.





Those parts are really too flimsy to do much good on their own; they only provide a flange for a couple of far more robust parts. Those heftier parts were tricky to find. A few passes through the inventory sheet showed no sign of them. I finally found them in the inventory sheets that list the contents of the brown paper bags. Those bags are mostly for rivets, nuts, bolts, and other small-ish pieces-parts, so I didn't think to look there until all other options were expended.



And here's where the wing comes in, so to speak. (Did anyone get the joke there? These are receptacles for part of the wing, so by definition they are where the wing comes it. Get it? No? Oh well.) Anyway, the next step is to carry those little guys over to your wings and file the inner semi-circle to a nice, tight fit with the tabs on the aft spars.

Except, I have no wings.

Back when I was trying to decide which kit to get next, I had no idea that there was a dependency on having the wings when building the fuselage. Fortunately, it seems that the parts on the wing are pretty standardized and I should be able to get away with using someone else's wings. And I just happen to know at least two people withing an hour's drive that have RV-12 wings. It should be just a quick road trip to get this step done.

Looking ahead in the plans, it seems that I can fill a day or two with stuff that isn't dependent on having this part done.

It's been awhile....

It's been awhile. Since what, you wonder? Well, it's been awhile since I've worked for any length of time in the shop without having to drill out any rivets. A laudable accomplishment made possible by drilling one out last night.

I only managed a half hour working on the plane yesterday, but it should have easily been enough to finish the one thing I wanted to get done: squeezing in the rivets for the left side baggage floor, the very part that has given me a permanent nervous tick in my left eye. With the little reverse dimples caused from over-driving some rivets flattened out through the expedient of tapping them with a little hammer and the floor clecoed in place, it should have been a simple matter to just work my way down the row squeezing in rivets. And you know what? It was! So easy, in fact, that I squeezed one in that I shouldn't have.

Van's, realizing that they might face a mutiny from builders fed up with squeezing AD4 rivet after Ad4 rivet, courteously put one blind rivet in each of the left and right rows to give us a break from the strain of squeezing solid rivets. And a wonderful respite it would have been, too, had I been paying attention sufficiently to avail myself of the opportunity. I wasn't.

So, it had to be drilled out. On the plus side, drilling out a rivet that has responded to the compression of the rivet squeezer simply by leaning a little bit over to the side has to be the easiest type of rivet to drill out that there is. As opposed to, say, over-driven rivets. Those are the polar opposite.

Having gotten that out of the way last night, I was able to focus on getting the baggage ribs riveted into place. Having forced them into place with clecos previously during my misguided and ultimately detrimental attempt to use them to support the baggage floors, they slipped right into place this time around. I have a new tool in the shop that I was able to use to verify that I had them positioned correctly in the form of this nifty little 2.5 pound netbook:



I guess to be completely accurate I would say that I have this nifty little electronic gadget that I can use to verify that I either have everything positioned correctly, or I made the exact same mistake as someone else. Either way is fine; misery loves company too.

Having gotten the parts in place, I had to spend some time with my Super Secret Van's Decoder Ring figuring out the proper rivets to use from this drawing:



That one isn't really all that complicated - there are only two different types of rivet in play and finding the correct positions for the flush head CS4-4 rivets would be easy since they would only fit properly in the dimpled holes. What took a little more thought was the "Install all the rivets so that the manufactured heads are on the bulkhead." Just in case you're unfamiliar with the term, an installed rivet has two heads: the shop head and the manufactured head. An uninstalled rivet only has one head: the manufactured head.

It's pretty easy to figure out which is which: the head that gets made in the shop (either from being driven or squeezed in the case of a solid rivet, or pulled in the case of a blind rivet) is the shop head. The head that came on the rivet from the manufacturer is the manufactured head. I knew that - I was just trying to avoid the implications of putting the manufactured head inside the channel of the center section. It doesn't take long after realizing that you're reading it correctly to start to wonder just how that's supposed to work since there isn't a lot of room in there for cleco pliers, hands, and rivet pullers.

You know those things that give you a sinking feeling of dread in your stomach because you just know they're going to be a real ordeal but then they unexpectedly turn out to be pretty easy? You do? Good. Savor the memory of those, because this ain't one of those times. This is a royal pain. Getting the clecos in (and later, out) and wriggling the rivet puller in there to try to pull the rivets puts the sides and backs of your hands in constant movement up against the sharp edges of the bulkhead and center section. I haven't has this many lacerations on my hands since my ill-advised performance at amateur night at the Japanese Steak House.



Getting them in there was the hard part because there wasn't enough room to open the cleco pliers far enough to get them off the cleco. They came out a lot easier, but then I ran into the problem of the bottommost rivet. That one required the use of the little real-pain-in-the-rear-location wedge tool to make it a little easier to get the rivet puller in there.



Easier: it's not the same as easy. Just so you know.



Here they are, though, all in a row.



Those were the hard ones. After the rivets in the center section were done, it was a simple matter to place the rivets on the top of the floors.



Done at last!



Well, not really. There are some nutplates that have to be installed yet. And, of course, an entire airplane to be built around this core. But I'm done with installing the baggage floors and with the troubles I've had getting them in, that ain't nuthin'!

Too clever by 62.5%

Why not "too clever by half?" Rest assured, we'll get to that. We always do.

I posted a question on the ever-helpful Vans Air Force dot Net site to see if anyone could shed some light on the problem that I had with a gap being created between the baggage floor flange and the Center Section (which I am still capitalizing as a proper noun because I'm on a first name basis with that part, as in "You ^#%*$# piece of %$@# Center Section") when I riveted them together. I received a very accurate answer:

Looks to me like you are waaaaaay over driving the rivets.
If unable to do it with the gun, why not just do it the recommended way with a hand squeezer?

To which I replied:

With the #4s, I use a Cleveland Main Squeeze. It has an unfortunate bulge that precludes use close to another skin. I might have to try it with a "regular" squeezer if I can't get a handle on driving them.

Which is also accurate, as far as it goes. But we'll get to that. First, about the over driving. If you look at the shop head on the rivet as measured by the rivet gauge, you will see that it quite plainly is not over driven. If fact, it's perfect!



Or so I thought. But then I saw this reply:

If a rivet is slightly too short to start with and an attempt is made to squeeze it extra hard to achieve the correct diameter shop head, then the rivet will expand too much inside of the hole and cause the skin to pucker.

Well, there ya go! That's exactly what happened! You learn something new every day, it seems, even if it's sometimes painful to do so.

No time for self recriminations, though, as the immediate problem at hand was the removal of the over-driven rivet. I stewed about that most of the night last night, literally losing sleep over it. It was also a nagging itch in the far aft reaches of my brain as I tried to concentrate on a difficult piece of recursive code at work; I ultimately failed at that too and punted to a less elegant but more comprehensible solution. You see, if the location of the rivet makes it hard to get at with a rivet squeezer, it's going to be just as hard, if not harder, to get to with a drill bit. I had to come up with a plan!

I thought the best approach would be to get a 90 degree angle attachment for the drill, but the only ones I could find locally were big, bulky affairs that were larger than the actual drill. No help there. That left me with the only other option I could think of: use the super-long #30 drill bit. I wasn't overly excited about using it to remove a rivet since 1) I usually use a bit one size smaller than the hole to avoid enlarging the hole, and 2) it's hard to be precise with that much bit wobbling around. As it was the only choice, however, I resigned myself to it.

Once I tried to line it up on the hole with the Center Section lying flat on the table, I could see that it would be more accurate to put the Center Section up on edge and drill straight down. I couldn't do that, though, because the "feet" were keeping the baggage floors rigid and I couldn't push them back a little bit to give the drill some room. The crowding problem was exacerbated by the fact that the floors are at a less than 90 degree angle with the Center Section. I would have to remove the "feet" to allow the baggage floors to lean back out of the way.

Did a light bulb just illuminate over your head? Don't look up, I meant that figuratively.

"If I can lean these floors back to allow a drill to get in there," I asked myself (rhetorically - I might ask myself questions out loud, but it would be weird to answer them too, right? I avoid the temptation by only asking myself questions that I don't have to answer), "wouldn't that also have worked with the rivet squeezer? Even if it did suffer from an inconvenient bulge?"

Yes. Yes it would. And it also would have kept the clecos from scratching up the surface of the baggage floors, an event the instructions warned me about with the suggestion to put some tape on the rivet squeezer. I'm so smart that I decided that since I wasn't going to use no stinkin' rivet squeezer, I didn't need no stinkin' tape. But with the floor pushed past the 90 degree angle by the "feet," it came into contract with the edges of the clecos and got all scratched up.

That brings us up to "too clever by half."

I removed the baggage ribs, pushed the floors a little bit back to get them out of the way, and started drilling on the rivet.



Eventually, after slow and diligent drilling, the head of the rivet popped off.



Now on some rivets, that's all you need; the remainder of the rivet will pull right out from the other side. But an over-driven rivet is a different beast indeed. You see, what caused the gap in the first place was some of the rivet spilling out from the top of the hole between the two pieces of material, in effect forming another head. The new head was still trapped between the baggage floor flange and the Center Section. The other three rivets would have to come out too.

I hadn't counted on that. When I was leaving the house, I remembered that I hadn't brought a fresh battery for the drill. Wouldn't need it, I thought, since I was only drilling out one rivet.

It died halfway through drilling out the third rivet. I was 62.5% done with drilling out the rivets when I had to stop because I was too clever to go back and get the fresh battery. Finally! Too clever by 62.5%.

Rather than head back home to get the battery and run the risk of getting trapped, I thought I'd try squeezing a few rivets into the other baggage floor to see if it was going to go any smoother than the first has.



It did. Although... the rivets are still a little too short. I don't think I'm going to be able to squeeze a regulation size shop head onto them. Maybe with the rivet gun....

Nah, not a chance.

This his how the flange is supposed to look:



They all went in fairly easily, although I found that there was a trick to getting the first little squeeze started with the floor leaning forward to keep the flange flush, then pushing the floor back to allow a straighter squeeze after the rivet was set enough to hold the flange in place.



Note the scratching from the clecos. Bummer, that. I think mine is by far the ugliest center section in the brief history of RV-12 building. That's kinda like my golf trophy: Worst in the League. I won that one pulling away. Of course, I couldn't hide my shame by painting the trophy - the same is not true for the baggage floors.

You think that side is ugly? You ought to see the other guy!

One of the effects of over driving the rivet is that it creates a kind of reverse dimple in the flange where the rivet material pushes it out of the way. I took the floor back home to try to work it back to flatness. After escaping an hour later to get back to the hangar and cleco the floor back onto the Center Section, I found that it still needs work.



I'm not sure I'll ever get it as nice and tight as the other side, but I'm going to give it at least one more try. I think it's always going to be at least a little ugly, though.