Category Archives: deburr

Tank attach brackets

I finished up countersinking the fuel cap brackets and moved on to the tank attach brackets. These have a bearing, some shims, and three different kinds of nutplates that need to be attached.

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As always, first I had to find everything.  I had put the shims by the brackets themselves when I was hunting up everything at the start of the chapter, but it took a while to dig out all the nutplates.  The MS21051-L08’s in particular were a bear to find.  They are in bag #3015.  They are the only nutplates in there.  The spreadsheet of parts was very helpful! I separated the shims on the bandsaw and carefully deburred the holes (the instructions note to do a good job with this, particularly on the #8 screw holes).

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The shims have to be trimmed to match the ends of the attache bracket.  The narrow shim in particular has a very slim edge clearance to the outer nutplate hole.  I carefully sanded them down on my sanding disk to get the a close clearance.

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I marked the “primer line” on the attach brackets and started clecoing the nutplates in as I found them.  I’m substituting K1100-08 for the K1100-08D because I’m going to use “oops” rivets instead of dimpling the tiny shims.  I’m afraid that the shims will warp badly in the dimpler.  The hole on the end, in particular, is way too close to the edge for my to think about dimpling.

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I filed the cut marks off of the brackets before running them through the Scotch  Brite wheel.  The initial edge was a little sharp.  So I donated a few more drops of “Blood, toil, tears, and sweat” to the project.

The RV-12 was feeling a bit neglected.  The early low clouds had finally risen.  My son Ryan came down for the afternoon, so we fired up 3EN and did some pattern work.  He is getting ready to start his flying lessons, so I let him do one of the takeoffs and one of the landings.  He did a great job!

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I primed up the external parts of the brackets and shims and countersunk the brackets.  The picture shows a test fit.  The bracket lays tight to the skin and the shims have sufficient clearance.

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The final step for the day was to rivet the flange bearings onto the brackets.  This is where I really like working both right and left together.  I’m able to make sure I’ve got everything set up correctly.  The nice mirror image gives me some assurance that dyslexia didn’t bite me here.  I don’t show the riveting, but it came out pretty nice.

I have a few more things to finish up before diving into the Proseal.  I have to rivet some nutplates to the shims and then the shims (with more nutplates) to the brackets. I’m using the NAS 1097 rivet trick here rather than dimpling to avoid warping the shims.  I got the light countersinks done, but then had to jet to meet my wife for BBQ at Killen’s.

A day of dimpling

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When I left off last week, I had dimpled the #8 screw holes and hadn’t yet started in on the 3/32″ skin holes.  There are a lot of them!  Because of the way the tank skin is bent, I needed to do some work getting my DRDT-2 set up.  In New York, I had a nice bench with an overhang set up permanently against the garage wall.  For most work here in Texas, I can get away with bolting my dimpler to one of the EAA work tables.  For the leading edge and tank skins, I need a bit of an overhang.  I thought of a bunch of possible ways to set this up.  In the end, I did something very simple and effective.  I used some 3.5″ x 5/16″ lag screws and a piece of 2×6.  This very solidly tied the extension into the table.  A couple of 1″ lag screws holds the dimpler to the 2×6.  It worked very well.

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So I sat in the comfy chair and twirled a dull drill bit in the holes.  I like this method. It is very fast and easy to control.  It just barely takes off the burr while leaving the hole nice and smooth.

I had high hopes of getting in some practice touch and goes, but all thoughts of that were quickly dashed.  It really poured! Even when the airport was in the clear, there were nasty thunderstorms lurking all around all day long.

The DRDT-2 and the carpet covered boxes worked vey nicely.  The dimpling went quickly, but there were still SOOOO many of them!  I finally got all of them done…

Next, I worked on the fuel caps.  There’s a pretty red anodized base and a cheap looking plastic sealing cap. I can get replacement ones made out of machined aluminum, but at $145, it is pretty pricy.  I don’t like the idea of painting the plastic though.  Will likely defer until it is time to paint the plane.  There are some steps, that I’m really excited to get to.   One of them is this shot of the fuel cap base clecoed in.  Pro-seal time is close at hand!

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One clever hint I saw is to set up a swiveling base for the stands.  The Pro-seal is messy and hard to work with on a good day.  These swivels will let me rotate the tank so that I have a good (better?) angle for both applying the sealant and for riveting.  Not quite done in this picture.  I cut these pieces from the end of the 2×6 I used to support the DRDT-2.  Added a rounded edge and then drilled them out for a 5/16″ hex bolt for the axle. We’ll see how they work soon enough.

Next time, I have a few non-Pro-seal tasks to finish on the tank attach brackets and shims. Standard trim, deburr, prime (just the external parts), and rivet.  If I get really saucy, I’ll do the nut plates on the inboard rib (screws pull in the fuel lever sender.  No gasket, only more tank sealant).  If I’m super productive, I’ll do the first set of sealant tasks (closing the tooling holes and adding the fuel flanges and anti-rotation plate).

Just the right leading edge…

Some blog posts just aren’t vey exciting.  This is one of them.  Having set up the left side leading edge (with exciting stall warning vane hole and access panel!), it was time to do it all again on the right.

The right side was all cleco’d and match drilled, so it was time to disassemble, deburr, and prime.  I also pulled off the blue plastic while the skins were stiff in the jig.  This is still very time consuming, but I’m getting faster and cleaner with my soldering iron.

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I started by deburring the J-stiffener and then got to work on the ribs.  My friend the dentist dropped by to help, so while I was scrubbing the ribs with Comet, he was rinsing and drying them.  We got them all clean, dry, and primed pretty quickly.  I had a bit of a time getting the splice strips in place.  I found that by clecoing from the outside in (see below), I was able to stretch and wrap the splice strip tightly to the rib.  Then I inserted clecos from the inside out so I could gently push the splice rib into the leading edge skin.  I could then extend the clecos to grab the skin.  Then I could go from the outside (this time with the skin) back to the inside.

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Voila!  The right side is ready for rivets!

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Next up… I’ll rivet both left and right leading edges.  I’ll also get the stall warning installed.  I won’t do the final install to the spar since it will be easier to deal with the wings as parts whilst trucking them to Chicago. I’ve read several posts on riveting these sections.  Some suggest laying the leading edges flat while others suggest going in from the top (as positioned now).  I’ll figure out what works best for me when I actually get started.  I do want to make sure that I protect against dropping the bucking bar.  I would be very easy to put a massive dent in the leading edge.

I did get a new tungsten bucking bar.  This one is actually a surplus rotor balance weight from a Cobra helicopter.  It’s about a pound and a half and sits nicely in my hand.  We’ll give it a try soon!

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Slow cooked ribs…

I needed to finish prepping the remaining 18 wing ribs.

The weather was much improved from a couple weeks ago.  The shop was a whole 45 degrees F when I opened it up with no snow outside.  It really improved the ventilation for the priming.

20 or so minutes per rib to

  1. Uncleco from the spar where I had them sorted
  2. Mark and remove the spar bolts
  3. Check the sizes and locations of the snap bushings
  4. Mark the location of the bushing hole that wasn’t pre-drilled
  5. Drill a pilot hole for the snap bushing
  6. Step drill the 1 to 3 bushing holes
  7. Deburr the holes
  8. Deburr the rear-most lightening hole (too big to get with the Scotch-brite sanding wheel)
  9. Hand deburr the little slots in the flanges
  10. File the rough flange edges to something smoother
  11. Run the flanges through the big Scotch-brite wheel
  12. Shoot it with primer in the paint booth
  13. Mark the rib with it’s location
  14. Hang it up

That’s all I did… all day long.

I caught my knuckles on the spar a couple times trying to break the spar bolts loose.  There’s a sharp edge from the big double plate that just wants to grab you.  My father-in-law expressed no sympathy and simply suggested that I paint the whole thing blood red.  I was actually thinking about that as a color scheme.  Here’s a very nice paint job that I like!

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But in the end… All the ribs are ready for the next steps where I’ll install some snap bushings, rivet the flap attach and torque tube assemblies, match drill the bolt holes for the ribs, and install the ribs (rivets and blots).  The instructions call for doing the match drill step earlier, but I didn’t have the right sized socket to pull the bolts.  Easy enough to do in this step.  I should finish section 14 in the next build session and my wings will start to look like real wings!

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Bulkheads everywhere….

Even with mass this morning and fixing the Christmas lights, I got to the shop by 1:30 for about 5 hours of work on the bulkheads.

There are five bulkheads.  I riveted the aft-most one yesterday and deburred and primed the next two  Those came together pretty quickly.  With lots of cold 1/8″ rivets, it was easier to hand squeeze than to use the pneumatic squeezer (better control and more oomph by hand!).



I clamped my hand squeezer to the table which made the riveting much easier than holding an unweildy bulkhead and a rivet and a squeezer all at once.  It also made it a lot easier to get a good push on the arm and make best use of its mechanical advantage.


The rear three bulkheads take up only 20″ of the fuselage!  They have bulky straps to hold the vertical and horizontal stabilizers in place.


The next steps seemed so simple…  The 2 forward bulkheads only have a few rivets and no thick aluminum straps to mount.  However, they are very large (compared to the other bulkheads), are made in two pieces, and have many, many nooks and crannies to deburr.  I filed the worst parts of the outside with a fine file, hit the many lightening and system holes with sandpaper and scotchbrite, and sanded around each of the approximately 10,000 flange tabs.  Then I finished the accessible edges on the scotchbrite wheel.  I used almost (but not quite) all my remaining primer priming the bulkhead parts.  Not too many rivets to do and the squeezer was still set up, so I thought I would bang together the last two bulkheads.  The first one went together very quickly (only 5 rivets as you leave the top 3 open for later riveting).  The second one has ten rivets (an extra two hold the rudder cable bracket to the bulkhead).   On my very last rivet, the squeezer apparently shifted so I got a smile rivet to drill out next time.

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So, the bulkheads are done for now.

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The next steps are to deburr and prime the bellcrank ribs and one more, thankfully small, bulkhead.  Then the bottom skin goes on and it starts to look like a real airplane body.

Bulking up… working on the rear fuselage bulkheads

I only had the afternoon to work on the plane today.  The contractor’s minions were working trying to get our 8 week project (now in it’s 9th month) done.  I got to the shop around 1pm and in the first five minutes managed to blow the breaker.  The garage is very power challenged; it has barely enough juice to power my compressor.  Today I tripped it with a heat gun (pre-warming the oil in the compressor), a microwave oven (heating water to pre-warm the rattle can primer), and my propane heater (to pre-warm me!).  Unfortunately, the breakers are in the locked basement of the rental house, so I had to call the landlord’s son to pop it back on.  He couldn’t get there until 3pm!  So I worked by the light of the garage windows.

First up, I riveted the small rear bulkhead and tie down together with my hand squeezer.  I probably would have gone for the manual squeezer anyway, but with the power out, I had no choice.  The longeron yoke was perfect for getting these.

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Everything fit nicely and it was good to get the first piece of the fuselage actually done.  So here is page 10-08!

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With no power I couldn’t do a lot on the next bulkhead, so I instead hunted up all the parts for the remaining four bulkheads.  The first three bulkheads all have some extra bits attached and some holes to drill, so I set those up.  I actually got the second bulkhead clecoed together and fitted to the rear skin.  A couple of the flanges needed some finagling to get right, but it mostly lined up well.

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With the power back on, it was back on the pre-drill, deburr, dimple, smooth, prep for priming, priming train.  I had already primed some of the attach straps in the previous step, so they just needed touch ups (because the final drilling left some raw aluminum exposed).

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These are now all primed and ready to assemble.  I’ll get the final two bulkheads tomorrow.  These parts are the biggest I’ve worked on yet.  It’s kind of exciting to go from the small rear bulkhead to the back of the baggage compartment.  Still lots of pages to go on the rear fuselage.  The wing kit is just sitting there, taunting me!  I’ll be started on it soon enough, I hope.

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Back to the grind… Wing inventory and the rear fuselage

Sunday, 30 November

inventory only took about 3 hours.  Lots of new rivet types.  So many nut plates that it made sense to sort them into their own bins.  Many of the drawers that were almost empty are now full again!  These are all the new rivets ready to go back in the organizer.

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Most of the parts are actually in the smaller spar crate.  It is packed very tightly.  The spars are truly beautiful.  Individually numbered too!

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And, the wings are officially a “project.”  As anyone knows, you need at least 3 trips to the hardware store and, in my house at least, a blood sacrifice.  I snagged my knuckle on one of the crate staples to satisfy the later requirement.

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With the wing parts unwrapped and cached in my cabinets, it was time to get cracking on the rear fuselage.  Right now, the wing crates are along the back wall (where the empennage crate sat) and the empennage crate is uncomfortably situated between the far wall and the work tables.  I’m hoping that I’ll get the crate emptied soon and recover the floor space.

The first part of section 10 is cutting out parts.  It feels weird to do this after such a long hiatus.  It seems like months since I deburred and primed parts (because it was months ago!).

I went to cut the parts on my bandsaw since that is so convenient (one of the helpers I met during the EAA workshop told me that a bandsaw was absolutely required… he was right!). The lead counterweights for the elevator, in addition to being cut wrong, also dulled my blade, so it will be (another) trip to the Home Depot Aviation Supply Store.  Meanwhile, I cut the j-channel and other parts using my metal snips.  You also have to modify the F-1037B part to have a little chunk out of one end.  I marked it up and drilled the hole (just used my electric drill as it was not worth the effort to fire up the compressor).  The plan is to rough cut the notch and then file the edges to ease up on the nice round corner. I’ll get a new saw blade and finish the rest of the cuts later.

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So not a bad afternoon!  Inventory done (no parts missing) and a few parts rough cut!2014-11-30 16.38.43

Tuesday, 2 December

Well, my contract job ended on Monday and, while I have a new job in the works, I’m gainfully unemployed for a week or two.  So, I got to work on the plane mid-week!  I’m hoping to get most of the rear fuselage done by Christmas when I can get my kids to help with the riveting.

I got a new propane space heater for the garage.  I worked last winter when the temps got down to single digits and that is just too cold.  My garage space is way underpowered, so electric heating is out of the question.  I can run this new heater for just a few minutes to bring the temps up to the mid-40’s or 50’s.  Warm enough to work, short enough to avoid CO poisoning.

I also ran to Home Depot to get a new bandsaw blade.  It was the wrong size!  So I had to go back and exchange it.  Finally got to work much later than I hoped.

I started by reworking the trim tab push/pull arm.  Van’s issued a service bulletin about the arm (the original design was a little too short).  I didn’t like the way the original one turned out anyway (and was planning on re-ordering), but I got a new one tucked into the wing kit!  The photo makes it look much longer, but it is only a tiny bit bigger.2014-12-02 16.46.47

Page 10-04 is quite daunting!  I have to fab two parts from (not quite) raw angle.  It’s not as bad as a scratch built because the angle is all cut to length and there are predrilled holes.  Not too much to go wrong.  Also, the plans have full size drawings to allow you to check the part easily.  Good thing too as I cut the top too shallowly on my first try.  I used a piece of 2×4 to run the part through the bandsaw (with a new blade!).  I read that the wood helps clear the soft aluminum off the blade teeth.  The cut went pretty easily (even the tight bend at the bottom wasn’t that hard.

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The cuts were very rough.  WAY to rough to run through my Scotchbrite wheel.  I clamped the piece to my bench and used a bastard file to dress the edges (and work my way up to the cut lines).  I did the raw ends on my belt sander disk.  I got nice sharp, shiny, smooth edges out of that.

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In the end, I got a part that very closely matched the drawings.


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Giving me a pile of un-deburred parts to deal with later.

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Tuesday, 3 December

I got another late start on the day as I had to hang around in case the contractors actually showed up (they didn’t) to finish our remodel work.  Nothing much to show for the morning, but a couple of small deposits in the bank of marital bliss.

So, it’s back to page 10-04 and fabricating the two rudder stops. These may eventually get swapped out (some builders complain that the default stops don’t work well), but it is at least a more interesting fab than the horizontal stabilizer attach bar.  I tried printing out a full size template, but I found that it was actually easier to mark the angle directly from the full size drawing on the page. I then used the wood block trick to make the angle easier to cut squarely.  Conveniently, the round corner of the angle fit nicely into the rounded corner of the 2×4.

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A few passes through the bandsaw and I had some (very) rough cut parts

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These needed some serious filing (I accounted for that in my cuts).  So I clamped the parts on my bench and went to work.  I did some final polish with the disk on my belt sander.

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Unlike the horizontal stabilizer attach bar, these holes also need to be reamed and countersunk.  The rear holes are much to close to the back to get my countersink cage in.  In fact, they are too close to even get the countersink bit in!  Luckily, my deburring bit is a touch smaller and it fit nicely.

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This gave me two parts that match the spec very nicely.

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After a stop at the scotchbrite wheel, these parts were done.  So I shot some rattle can primer to finish them up.

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I had skipped a step on page 10-02 previously.  You need to straighten the F-01411C attach bars to within 1/16″.  They start out with a distinct rounding (maybe 1/4″).  The plans (which are normally written in spare engineering terms) have the most amusing illustration to show you how to straighten them out.  It looks like it is straight out of a Batman comic.


It is actually very helpful!  I brought along my rubber mallet from home (that’s why I previously skipped this step) and tried to do it just like the drawing.  I think I succeeded!  At least the parts where straight to within 1/32″ when I finished.

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Then the parts needed some serious filing.  The machining work is very rough.  There are about a dozen tags on each piece and even the straight parts need a lot of work. Again, it would be lunacy to attack these with a scotchbrite wheel.  The bastard file did a great job shining up these edges.

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This made a lot of magic pixie dust!

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With the hard work done, I ran all the small parts through filing, deburring, and polish on the wheel.  A nice new pile of parts ready for priming!.

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