Monthly Archives: May 2014

Horizontal stabilizer assembly (and many countersinks)

Rivet count:  779 + 32 = 811 rivets!

The family visitation is over (nephew and 3 friends plus brother-in-law and his family), so it is back to work on the plane!

With only a half day to work, I wasn’t sure I would get much done, but it was a pretty productive day.  I started by priming the horizontal stabilizer skins.  I ran a full coat over each rivet line and then a lighter coat of filler between.  The hardest part was getting the blasted blue plastic off the skins.

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The next step was countersinking the spars and the stringers.  There were a lot of countersinks to do.  426 of them!  I used a rivet to check the depth as I went.  Even with the countersink depth set, you still have to watch it.  The drill needs to be kept perpendicular and it can still be overdriven.

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With all of the countersinks done, I added a light coat of primer on the flanges.  Hopefully it will help prevent corrosion in the countersinks

So finally, assembly can begin.  The first part to go together is the stringer assembly.  This is the V shaped part that fits into the very end of the tail cone.  The instructions showed assembling it separately from the spar, but I wanted to assemble it on the spar to make sure I got the orientation correct.  The first part is a brace that goes between the modified intra spar ribs.  I put the shop heads on the outboard side… probably would have been better to keep them on the inboard side.  Next I had to cleco and rivet the stringers.  A little bit of primer got in the holes, so I had to run my 1/8″ reamer through the holes to clear them.  I was able to squeeze all these rivets.

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Next up… I start assembling the rest of the skeleton and put the whole thing into the riveting cradle to get the skin riveting.  I’ll have to shoot most of those, but I’ll finally crack the 1,000 rivet barrier 🙂



More prep work on the horizontal stabilizer

Even with company in town, I managed to get a little time out in the shop.  Today, I talked my brother-in-law and nephew into coming out to help.

The tasks today were a bit boring and repetitive… dimpling and priming.    There are about 160 dimples in each face of the horizontal stabilizer skins (4 faces).  With two people (even if one is a small one), it goes much more quickly than solo.  The DRDT-2 dimpler made it easy to get at those inner dimples even on a folded skin like this one.

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With that done, we primed the various parts.  This was my nephew’s first time using a rattle can.  A few reminders about keeping the can upright were needed, but he did a good job.

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The next step is to do the thousands (well hundreds) of countersinks on the spars.

Polish and buff, polish and buff, …



Rivet count: Stuck at 779 rivets for the moment…

Shop Temp: 97F

A rare mid-week shop day for me!  I quit my day job on Friday and won’t start my interim job until next Monday.  The family was in the city visiting the Statue of Liberty, so I was able to get out to the shop for the whole afternoon!

It was all grunt work today.  I had bunches of nose ribs and intra spar ribs to smooth out.  It took a while, but between a needle file, the polish wheel, and some ScotchBrite, the edges are pretty smooth.

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After getting that done, I had to modify a couple of the nose ribs and intra spar ribs to angle out from the front spar.  This forms the edge near where the empennage attaches to the tail cone of the fuselage.  Mostly some quick work with the hand seamer to get that done.

I also had to fabricate some cradles to hold the skin and skeleton during assembly.  The instructions stress that a rough job is fine.  This is not a jig, the frame is self-jigging.  It is just something that holds the skins in place while doing the riveting.  I traced the outline of a nose rib and intra spar rib as shown in the instructions and then jigsawed the four pieces.  I added a wooden bracket at the bottom that I will screw into the table top during assembly.

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Next up, some actual assembly work!  You cleco the modified nose ribs and intra spar ribs to the center of the front spar and do some match drilling.  Hardly worth firing up the compressor to run the drill.  Lots of cautions to mark several holes to avoid dimpling them.  Also, the top and the bottom are treated differently (the pattern of nine rivets in a square shows that the spar is properly oriented).


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Then the real grunt work begins.  I started prepping the skins for dimpling.  The skins are symmetrical, no left no right, no top no bottom.  Until, that is, you start marking the skins. So I spent some quality time with my soldering iron removing blue plastic.

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With that done, I started filing the burrs and tool marks off the skins.  There is a cutting tab every 4 inches or so around the outside of the skin.  I filed those off first.  Then I used some sand paper to remove those tool marks, and then finally finished with a ScotchBrite pad.  The change is remarkable.  From something that would snag and cut your skin to something with a mirror polish.

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I still have a little work to do on them.  They also need to be dimpled, but I ran out of time today, so they’ll wait for later.

I did sneak a peek at the next step in the instructions.  I did a test fit of the string web assembly.  This strengthens the tail right near the tail cone.

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Next up, lots of dimpling and lots of countersinking… both spars and the web stringers need to be countersunk for the skin attachment rivets.

After that, it will go together quickly 🙂




Smile.. I’m still making progress!

Rivet count: 603 + 46 + 130 = 779 rivets!

The blog has been dark for a month, but progress continued albeit slowly.

Lot’s going on back at the house and at my “real” job and that is distracting from my important work here at the factory!

The renovation at the house continues.  It was supposed to be done by now, but that isn’t how it works in real life.  Complicating matters my nephew and 2 of his friends are coming out for a visit this Wednesday AND my brother-in-law is visiting with his family on Thursday.  Sigh.  And I just quit my day job (Yike!). Hardly any time for building (but I do have a plane reserved for all three days of Memorial Day Weekend!).

The big news is that I started the horizontal stabilizer, so I get a new background picture.


April 26

So, I finally finished rolling the leading edge of the rudder.  It was hard to get the roll tight, but it all came together nicely in the end.  The edge lays up nice and tight except for one small gap.  The edge roller really helped get the skin to lay flat here.

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The next task was to figure out how to mount the thing on my wall!  I see lots of pictures of parts being built online.  And I see lots of pictures of parts hanging on walls online.  But I hardly see any pictures of how to hang the parts.  For the rudder, I cut a V shaped piece of wood on my table saw that fit neatly into the bottom.  Then I made a small shelf to hold the V piece. That made it a lot easier to mount on the wall.  I’m just using some plastic pipe strap to hold everything in place (and styrofoam blocks to keep it off the rough wall).

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With that out of the way, I starting digging out the parts for the horizontal stabilizer.  There are two big spars, some spar caps, and doubler plates to dig out to start.  At least this time I knew where to find the hinge brackets!  You start with the rear spar, but I decided to dress the edges of both spars before really digging into this part of the build.

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The spar is big.  It spans both my 5 foot tables.  The cut was very rough.  I filed down the worst of the edge with my file.  I managed to run the edge along my ScotchBrite wheel to get a smooth finish.  The lightening holes are a pain to smooth by hand, but I have some little wheels that fit in my electric drill that made pretty fast work of the deburring.

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I clecoed and match drilled the doubler plate and called it a day.

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April 29

I managed to sneak back out for some extra work on Sunday.  I got the rear spar and doubler plate primed.  Next I had to line up and match drill the hinges.  There are 4 pairs of hinge brackets (and a central one with a bearing riveted in).  I lettered them all to keep them straight.  I had to add some arrows to disambiguate the symmetric letters though.  The Sharpie shows through the primer (good!), so I placed the letters to be covered by the actual brackets.

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Lots of clecos to hold the doubler plate in place!

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Since the ribs get riveted in later, you have to be careful not to place certain rivets.  I bought a large roll of bright orange electrical tape that I use to mark these “do not rivet” spots.

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May 3rd

Another short day, but I did get a lot of things done.  I finally got a chance to get some rivets in.  There are too many to comfortably hand squeeze, so I fired up the pneumatic squeezer with the longeron yoke.  It worked really well for the doubler and for the hinge brackets.  46 rivets!

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The next task was to build a hinge bracket with a bearing inside.  For some reason, this was one part of the build that always looked really cool when I was researching building.  You need to take some care getting everything aligned, but it was not hard to match drill this.  Do remember to set an alignment mark so you can put it back together in the right order after deburring!


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One of the cardinal rules of riveting is to keep the piece from moving around.  Here also, we want to keep the “feet” of the brackets aligned.  Easy to clamp in place.  I used a 2×4 clamped to my table and then clamped the bracket where it was easy to reach.




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Voila!  The finished product!

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This then gets bolted to the spar.  This meant pouring over the manual to identify the correct bolts.  There is a chart in Section 5 that is helpful.

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I finally found the parts with the right lengths and proceeded to fit the bolts with my torque wrench.  Alas, I over-torqued at least one of the bolts.  This is dangerous because the bolt may break in flight.  For the 25 cents it takes to replace it, I’ll wait and try that one again.

The front spar is the next component on the list. I deburred the doubler and spar during the last step, so I was able to jump right into the build.  There are some spar caps that need to be trimmed and shaped.  I broke my band saw belt (again!) while cutting the very first one, so I used snips to get the other 7 ends.  The cuts made these awesome spirals.  I saved these for my daughter to make some shiny dangle earrings.

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Both my cuts and the factory finished edges were pretty rough, so I used my bastard file to do a rough edge dressing and then finished the edges on the polish wheel.


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May 17th

We picked up my daughter from college last weekend, so no time at the shop 😦

The big task for the day was to drill the spar caps.  They have to be carefully centered on the spar with 3/16″ beyond the last hole.  I got just enough edge clearance to make this work.  First you drill the (many!) holes through the spar web, then take off all the clecos and deburr.  Then you re-cleco the caps to the spar and do the spar webs. The instructions note that you should deburr between steps to ensure that you get a tight fit.  It was a lot of drilling and clecoing, but it all got done.  I didn’t take any pictures, but you have to countersink a lot of holes.  I carefully transferred the diagram from the instructions onto the spar to get the right holes.  The Sharpie marks wiped right off when I primed the spar, doubler, and caps.  Then it was time to cleco it back together for riveting.

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The orange wrapped clecos are where I’m not supposed to rivet yet.

My daughter was out at the shop (working on the earrings!) and helped with the clecoing.  She likes the rivet work.  Her great-grandmother was a bucker building airplanes in WW2.  Her grandfather (other side) was a MechE who build two planes.  I guess it is in her blood!

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May 18th

I was supposed to fly this day, but a front full of pop-up showers was coming in.  I was hoping to fly from 1-3pm or so…. Hmm.. KHPN had pop up showers starting at 3… perhaps I could start early and still make it to Orange County… No!  Pop up showers there starting at 1pm!  Well perhaps enough time for a quick run up to Poughkeepsie?  No, showers starting there at 2pm.  So I took a quick bike ride and headed out to the shop.  I spent the whole afternoon riveting the spar.  130 rivets or so…  7 different kinds (some flush, some domed with 3 different lengths).  I had to flip the spar over so I could get all the same types of rivets at the same time to minimize resetting the squeezer so much.

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Most went in just fine, but I had 4 problem rivets.  I had to drill all of them out (one of them I drilled out twice!).  My drilling out has measurably improved.  All of the rivets came out pretty easily and I did not enlarge any holes.

I read a lot about “smiley” rivets whilst doing my research.  I finally got one.  It was pretty, but I had to drill it out too 🙂

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The day was almost over, but at least I got a chance to start deburring the ribs.  Here are the nose ribs.  The cuts were very rough and had a distinct burr on the inside.   The polish wheel was a slow way to get these, so I used a file to rough them out.  I’ll finish the deburr and polish work next week when my nephew is out visiting.

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