Wednesday, July 31, 2013

09-06, Horz Stab Skeleton Assy

I see that it's time to do some documentation.   Today's entry celebrates the completion of the skeleton of the Horiz Stab, although we did a bit more than that.  Below, in picture 0040, we see Nick (my stepson) on the far left, with two of his friends.  They came over for a day of playing around and ended up in the shop.  I riveted the ribs while the 3 boys peeled off the blue plastic from the R skin.  They did a great job, with minimal supervision from me.  It took all four of us (well, probably could have done it with just 2, but everyone got to help) place the ribs inside the skin in a nice, controlled manner.  It didn't take too much finessing to get the forward ribs and then the aft ribs to line up.   They were a bit confused at first, but then quickly caught on. 

Nick was ecstatic to be the 'guy in the know' when we ran into our first too-tight-to-fit rivet.  He fiddled with it, then I fiddled with it, then just said "Nick, #30 drill".  He lit up a smile, got out the drill bit, chucked it up and (with an "OK" nod from me) touched up the recalcitrant hole and popped in the rivet.  His buddies were duly impressed that he knew how to use a power tool.  


IMG 0040 2

Here are the boys, happy with their work for the day.  Nick Starling (mine), Nick A and Brandon.


IMG 0038 2

And finally, proof that I have completed step 09-06.

IMG 0039 2

Before we bid adieu to this topic, I will discuss one other issue.  The previous post discussed the difficulty getting the R hinge brackets to be square.  I decided to read ahead and find the part that fits in the hinge brackets and do a test fit.  In the process, I discovered that the hinge holes in the hinge brackets were too small to accept the AN4 bolts and they needed to be final drilled w a 0.25".  That involved removing the outer hinge brackets.  I was able to drill the inner hinge brackets with the outer ones removed.  I debated drilling out the riveted nut plates, but decided to use a bit more finesse.  I drilled the aluminum bracket just down to the nut plate using the drill press.  The first one went flawlessly and I tested it with an AN4.  The second one got spun out of my hands when I put just  a touch too much pressure and the drill bit into the steel of the nut plate.  There was a single shaving of damage which I cleared away.  It too accepted an AN4 from both directions, so I re-inserted the hinge flanges and buttoned everything up.  I ended up having to loosen the hinge bracket yet again to rivet the R inboard forward rib because the drawing specified that the open side of the flanges face the hinge spar.  (Why couldn't it be the other way?  That would have left plenty of room to get the riveter in place!  I didn't see what would happen if I installed it backwards…)   I have ordered a 1/4" drive extension in order to get the torque wrench in there to make sure that I'm correctly torqued.    I decided to bend the L forward inboard rib just enough to rivet it into place.  I hate bending aluminum, but decided that Van's knew what they were doing when the called out the directions in that order.

Saturday, July 27, 2013

09-07, hinge brackets, AST hinge prep

Yes, I skipped page 09-06 for now.  I don't like the idea of the flimsy ribs being attached while I try to attach hardware.  The interference of the ribs with the torque wrench is much more than the the interference of the hinge hardware with the manual rivet puller.  I also don't want to have to set the skeleton aside while I got the skin out to drill the AST hinges.  My plan is to assemble the R half of the skeleton and then immediately apply the skin, then do the same for the left.

Today's mystery was regarding the fit of the bushing on the upper half of the right (left side of photo) hinge.  There's a noticeable narrowing of the gap between the hinge halves, perhaps 1/16th or so. (I'm amazed that I'm starting to be able to think in terms of fractions.  I vastly prefer to think in terms of mm, but apparently I am capable of learning fractions of inches after all.)   I ended up sanding down the bushing quite a bit.

I can't figure out why the bracket isn't square.  No proud rivets beneath it and no deformity of the underlying spar box.  I'll be sure to check that there's adequate lateral clearance between the hinge halves and the F-1211C hinge stops when the time comes.


IMG 0037 2

Tuesday, July 23, 2013

09-05, spar box closed

The spar box is closed.  Again, I missed a detail and riveted the outer box ribs because I failed to spot the word "inside" on the instructions.  Again, I'm getting very good at drilling out rivets…  Hope I don't run short at the end!

I've also cut & deburred the rib clips and hinge stops.


IMG 0036 2

09-04, nut plate installation

The nut plates have been installed on the insides of the forward and aft spars.  I needed to drill out the nut plates on the forward spar because I put them on the spaces that needed the doublers.  They came out easily and assembly proceeded w/ problems after that.


IMG 0035 2

Sunday, July 21, 2013

09-03, prep of counterbalance arm and control arms

This was the second time that we've got some steel parts instead of aluminum.  Very different to work on.

IMG 0033 2

It looks kind of like a flying goose, or a Klingon destroyer.  (If you catch that reference, pat yourself on the back!)


IMG 0034 2

This is a closeup of the attachment of the counterbalance arm w/ brackets.


Saturday, July 20, 2013

09-02, spars & spar caps prep

Prep work for spars and spar caps.  Countersinks have been sunk.  (You can't see the incorrect countersunk hole in this view, but I mis-counted and was one off on the "closely spaced holes".)


IMG 0031 2

Hinge brackets are separated as well as the doublers and spacers. 

IMG 0032 2

09-01, inventory of parts for Horiz Stab

The Horiz Stab is pretty complicated compared to the previous chapters.  Rather than just diving in and making mistakes, I decided to gather & identify all of the parts as today's project.  (Skins omitted from photo.)


IMG 0030 2

08-04, Anti Servo Tabs

Anti Servo Tabs completed without any particularly large mishaps or giant steps backwards.  I did have one episode of drilling out a rib (see prior post) but I'm feeling pretty good about it as it was an elective pro-active procedure instead of trying to fix a mistake.

IMG 0029 2

Thursday, July 18, 2013

08-03, preparation of AST hinges

preparation of AST hinges.

IMG 0028 2

08-02, preparation of Anti Servo Tabs

It's good to be back at work.  I'm really having fun with this project, despite the 3 steps forward 1 step back kind of progress.


Preparation of the AST skins was pretty straightforward.  no complications or retraced steps.  (Those are on the next page… :(       

I could have not pulled the blue plastic from the inside until after drilling the final holes in the back—that would have accomplished the removal of chips at the same time.  The ribs are riveted in place w/o any complications.


IMG 0027 2


Foreshadowing the next step 08-03, the control arms are to be riveted onto the medial surfaces (excuse me; inboard) of the ribs.  Perusal of VAF reports those are a pain to get to and there are several recommendations to rivet the control arms to the rib, then rivet the rib to the skin.  Needless to say, I had already riveted in the rib.  

I tried punching out the center mandrel bit, but quickly realized that I would damage the AST in the process.  I elected to try a different technique and drill  with the mandrel in place.  Oddly enough, it worked great.  A #40 bit centered very nicely in the hole in a LP4-3 and stayed centered even when it it hit the mandrel remanent.  The #40 went straight through and then using a #30 and some precessing I was able to pop off the heads without damaging the underlying skins.  The control horns are then attached the ribs and the ribs re-attached to the skins. 

The last conundrum is that the admonitions to be very careful in labeling the horns and the skins appears to be for naught.  There is no way that the correctly labelled parts are correct.  I read ahead many pages to ensure that the control arms are bent outboard from each other and will have a clevis between them.  If you assemble things the way they are labelled, that isn't what results.  I feel like I am on the right track with that because when I watched the "How To" video, they also state to be very careful with the labels but you can clearly see them attaching the L Control Horn to the R AST Skin.

Saturday, July 13, 2013

07-05, Rudder

This is the fun part of building.  Fitting the skin on a skeleton and buttoning it up.  I enlisted 'Little Nick' to help position the skin and start aligning it.  As we were doing so, 'Big Nick' arrived and we put him to work installing clecos and placing blind rivets.  He only helped out about 10 minutes, as he was really there to take Melena out on a date but it was fun initiating him to the Brethren of Sheet Metal Workers.

Looking at Van's website, they are calling for an 8 week lead time for either wings or fuselage kit.  I think I'll call them on Monday and find out if either is on a potentially shorter time frame, and if so, order that kit.  If they are both equal lead times, then I'll order the wings.


IMG 2509

07-04, rudder skeleton assembly

The rudder skeleton assembly. 


IMG 2508

07-03, rudder spar w/ 1st rib

One rib has been riveted in place and another rib has been trimmed for placement on the control horn.  I really messed up some of those rib rivets.  I had clamped the spar to the table and was quite proud of myself.  I riveted the rib, but didn't unclamp the piece to turn it over to check my work.  I went forward and riveted the spar caps and hinge brackets before I realized that the rivets weren't driven enough to pass inspection.  Deriveting the hinge brackets was a complete disaster, and one of the holes can not be called round with even the most generous interpretation.  I used 470AD4-6 (vs. -5's) in order to have additional material to expand and fill the hold, but still had some cleating.  After much debate, I decided to quit while I was ahead, as further drilling on that mutilated hole would sooner or later result in damage to the rib, and would only further weaken the underlying aluminum.  No, I didn't take a picture of it.  It's ugly, just trust me.


IMG 2507

07-02, rudder spar w horn & hinge

Rudder spar has upper hinge assembly and rudder horn clecoed in place. 

IMG 2506

06-07, back on track, Vert Stab completed

Well, that was a fun learning experience.  I believe I drilled out about 150 rivets in order to extract the wrong nut plates.  (In case you weren't reading prior posts, I assumed that a K1000-3 was smaller than a K1000-06.  Silly me.)

Per advice from VAF, I punched out the remnant mandrel from the LP4-3s.  I used 1 penny nails and a cleco plier to push the 'pit' out for most of them as I was afraid to swing a hammer in the general direction of my work pieces.  There were several that did require a long punch (actually the mandrels from previous rivets) and a steady hand and good faith that I wasn't going to bash my stabilizer, but good results were to be found.  After that, a #30 drill wielded with a precession motion was most effective in twisting off the top of the rivet.  A pair of old diagonal cutters to pull off the tail did a nice job.   The flat rivets required drilling out and I didn't do too badly with those either.  I used a #52 to make a pilot hole, then popped the head with a #40, again using a precession motion of the entire drill.

The most satisfying part of the whole thing was putting the errant nut plates into their correctly labeled bin for later use.  

Re-assembly went well, as it would be expected, since I had the practice.  Hinge hardware was bolted and tie-wrapped into place as specified.  I also removed the nose piece and tweaked some of its edges so they would sit tighter against the main skin.


IMG 2504

Wednesday, July 10, 2013

confirmation of setback

While I'm out of town, I finished up my research by posting a cry for help on VAF and getting relatively consistent answers, but nothing concrete.  I then wrote to Van's and asked point-blank:

Subject:        Re: identification of nutplates
From:           David Hill <>
Date sent:      Tue, 9 Jul 2013 11:07:29 -0500
To:             "" <>

I've made new bins for everything, but I'm still not sure which is
which. Is an -06 smaller or larger than a -3?


A # 6 screw is quite a bit smaller than an AN3 bolt, so the threaded opening on a K1000-06 is 
smaller than the one on a K1000-3.  The rivet holes will be the same.

If you're not familiar with basic sizes of screws (#6, #8, etc.) you'll have to learn them.  Then 
there's number drills and decimal fractions, along with imperial fractions.  It will make you 
seriously yearn for the metric system...

Well, I do seriously yearn for the metric system, but this event really rivets my attention on the matter.  (Sorry—couldn't resist.)  I've clearly screwed up and placed K1000-06 nut plates instead of K1000-3's.  When I get home, I will have about 150 rivets to drill out.

Oh, well. This project is all about learning and being an expert de-riveter is a skill, too!

Further perusal of VAF describes using a small nail (or an old mandrel?) to punch out the steel mandrel remnant in the rivet to be drilled out, then using a slightly smaller drill than the original hole calls for (e.g., a 32 or 33 vs. a 30) and possibly a pair of diagonal cutters to prevent the rivet from spinning.  I'll let you know how it goes.

Saturday, July 6, 2013

major setback #1

Well, it really felt good to finish the vertical stabilizer. All I had to do was bolt the upper hinge assembly to the back of the rear spar and I would be done with my first complete part—the Vertical Stabilizer.   Unfortunately,  I had a sinking feeling because the inside of those nut plates looked a bit small.   I spent some time with good lighting and some calipers and confirmed that I had made a mistake by assuming that a K1000-3 was smaller than a K1000-4.  Damn.  I think I really screwed up by installing -4's inside the assembly instead of -3's.

from a posting on Van's Airforce

I am just going by memory. If I am wrong, someone will correct me.
3 stands for 3 sixteenths or #10 screw
4 stands for 4 sixteenths or 1/4"
6 stands for #6 screw
8 stands for #8 screw
A 1 in the hundreds place means the nutplate is designed for dimpled skin.


I'll be damned if I can find any straight answers for the sizing information on these nut plates.  As near as I can find, a -3 implies that it will accept a 10-32 screw.  Great.    Now what?

From we learn  ("A"=diameter of screw, "B" = diam of head, "C" = height of pan head)

Decimal Dimensions
  “A” Flat and Pan “B” Flat Head “B” Pan Head “C” Pan Head
Size MaxMin MaxMin MaxMin MaxMin
6-32 .137.131 .279.244 .270.256 .097.087
8-32 .163.157 .332.292 .322.306 .115.105
10-24 .189.181 .385.340 .373.357 .133.122
10-32 .189.183 .385.340 .378.357 .133.122
1/4-20 .249.236 .507.452 .492.473 .175.162

To convert the decimal dimensions shown above to fractional dimensions, simply multiply by 64. The result will be the number of 64ths of an inch equal to the decimal dimension. For instance, the thread size on a 1/4-20 screw is given as .249". Converting to a fraction, multiply by 64 (.249 x 64 = 15.936). The answer, 15.936, rounds to 16/64, or 1/4 of an inch.


Corresponding Fractional Measurements
  “A” Flat Head “A” Pan Head “A” Round Washer Head “A” Truss Head
Size Approx. Dia Approx. Dia T maxApprox. Dia T maxMaxMin
4 7/32 7/32 3/32N/A N/AN/AN/A
6 9/32 17/64 7/64N/A 3/3221/645/16
8 21/64 21/64 1/83/8 7/3225/6423/64
10 25/64 3/8 9/647/16 N/AN/AN/A
12 7/16 27/64 5/32N/A N/AN/AN/A
14 1/2 31/64 11/64N/A N/AN/AN/A

With that bit of information, I can finally figure out that a 10-32 is 12/64" = 6/32" = 3/16"



small   K1000-3 ?      = 3/16 = 6/32
medium  K1000-4      = 4/16 = 8/32 
large   K1000-06    = 9/32 = 9/32

Now, I'm still confused.  These are the 3 sizes of nut plates in my kit.  I selected the smallest one because it was what I thought went with -3.  This appears to be the case, but the -3 clearly doesn't fit then AN3 bolt. 

IMG 0020 2


If I have to re-work this thing, here's the instruction sheet I made for myself.  (1-3 are unrelated  and are going to be done for QC.)

V-stab re-work:

1) remove Fwd Skin from VS Assy
2) smooth top edge of all residual excess material
3) break rear/lower edges inward
4) drill out rivets connecting VS rear spar to 
top rib, 
mid rib, 
upper main rib, 
lower main rib,
both edges of main skin
5) remove VS Rear Spar
6) drill out rivets connecting Lower Main Spar from Main Skin
7) remove Lower Main Spar
8) drill out rivets to remove incorrect nut plates from Upper Spar Cap 
9) replace with correct (K1000-3) nut plates
10) attach Upper Hinge Assy to VS Rear Spar / Upper Spar Cap !
11) re-rivet Rear Spar to Main Skins & all Ribs
10) drill out rivets to remove incorrect nut plates from lower edge of front spar
11) replace with correct (K1000-3) nut plates 
12) replace Fwd Skin Assy onto Main Skin
refer to this assembly as Vertical Stabilizer

Friday, July 5, 2013

06-06, vertical stab skin preparation

Fairly straightforward to prep the skins with dimpling and installation of nut-plates.  There was a moderate amount of excess material to remove from the front piece, and I think that it was left on as a side effect of the cutting & folding process at the factory.  The main skin had a tiny ~2"x2" tag left on and I simply don't understand why it would have been left on.  Maybe someday I'll talk with someone who is more conversant with metal working and get some info.


IMG 2477

Tuesday, July 2, 2013

06-05, Vert Stab Skeleton Assembly

I made much more progress than expected today.  The first few days of building were pretty much monomaniacal, and I ignored household chores & stuff.  Today was 8a-5p of catching up with those things (laundry, mowing the yard, tackling a project (below), paying bills and stuff.)

The related project involved moving the dryer exhaust vent out of the garage and to an outside wall.  I suppose the original architect (or builder, in case architects don't concern themselves with that level of detail) didn't want to have the vent sticking out on the front wall of the house, but the porch is pretty protected and we have a swing in front of where the vent surfaced, so I think it will be all right.   The reason I'm even mentioning this (aside from wanting to get rid of a source of hot moist air) was that I hate making cuts and drilling holes into expensive things.  You know, houses, airplane parts…   This project (RV-12) is allowing me to learn that I really can do things with my hands and create (or at least assemble) stuff that is important and meaningful. 

Anyway, back to tonight's documentation.  Here is the V-stab skeleton.  It was quite tricky figuring out how to rivet the nut plates, as there is not much room to get the squeezer in there.  I did eventually figure it out, but I did have to drill out another rivet; this time on a partially completed, flimsy and delicate assembly.  I did it anyway!


IMG 0015 2




Monday, July 1, 2013

06-04, vertical stab spars

Nut plates have been added to the rear and front spars.  I had my first opportunity to drill out a rivet.  Turns out the rivet wasn't bad, it just wasn't attaching anything together.  Somehow, I had bumped a clecoed nut plate such that the rivet didn't go through the hole and when I set the rivet, the nut plate simply fell off.  Drilling it out wasn't too bad, but I dread the process when I have a partial airframe to navigate instead of easy-to-move bench-sized parts to play with.   Can you tell which rivet was re-worked?

IMG 0014 2

06-03, rudder spar cap preparation

It's a bit hard to make out, but there is the vertical stabilizer spar and the upper and lower end caps, all drilled and deburred. 

IMG 0013 2

06-02, rudder hinges

With great fanfare, I present to you the first assembled components of RV-12-0760!

IMG 0012

I'm going follow ng to the advice (example) of DG—a local builder who let me drool over his -12—and just make the title refer to the page number of parts/steps that I have completed.  This will save me from trying to come up with snappy titles on a regular basis and should facilitate anyone who wants to look at how I did a certain part.

I've already started on 06-03, and it's much more challenging.  I'm pretty sure Van decided that making the hinge assemblies was a great ice-breaker or confidence builder!

Project #2

I spent 2 days working on project #2, a section of airfoil provided by Van's as a training project.  Nick spent some time with me in the shop, but he's not quite as fanatic about this as I am. :0)     I think I put about 10-12 hours total into this, much of which was the 'now what do I do to fix that?' mode.   Like the toolbox project, this required several modifications to achieve my goals of learning techniques appropriate to the RV-12.  (I think that this is an aileron section from an earlier design.)   The plans call out for driving rivets in awkward locations, including spaces that are too tight and some that are too far from an edge to use a squeezer.  It also called out double flush rivets for the trailing edge and for me to roll the leading edges.

The plans (1 sheet) reminded me to go back and re-read sections from Chap 5 to get details on those little details, but my version (RV-12) has had Chap 5 conveniently revised to state "these techniques are not applicable for the RV-12".  In other words, I was on my own.   

All in all, it's not bad.  There are several rivets that I would drill out and replace, but the kit did not have any spares of the type of pop-rivet used in the leading edge.  The double flush rivets on the trailing edge were tricky, but that's exactly why I went ahead and worked on them anyway; they don't look terribly pretty, but they are flush to the feel.  I was pleased with the fact that I came up with a way of using a squeezer; I took a 1" section of AEX-Wedge from the kit and taped backwards it over the tail of the rivet; the sandwich of sheet-wedge-sheet-reversed wedge made a parallel surface for the squeezer to work with.  Not too bad for a kludge job.  The other major 'huh, what do I do now" moment was dealing with the rivets at the trailing edges of the ribs:  no way to get a squeezer in there, so I used LP4-3 pop rivets instead.  Well, I did on one side.  The 1st rivet prevented the 2nd from fitting in until I spent many noisy minutes with a Dremel tool to cut down the 1st pulled rivet in order to make room for the 2nd. (N.B., Not an acceptable technique for a flying bird; strictly for demo work only.)

update 12/27/13:   I have since learned that the technique to deal with the inadequate clearance is to pull the 1st rivet normally, insert the opposite rivet and apply inward pressure as you slowly pull the stem.  The second rivet shortens enough to clear #1 and then sets normally.

IMG 0007 2

Work in progress.


IMG 0008 2

Finished project #2