Prepping and Priming Some Rear Spar Components

November 20, 2010

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Oh man, I’m furious. I just spent some time doing a huge writeup for this post, and when I clicked, “Post”, it deleted all of my text.


I’ll try to rewrite it, but it is going to have a little bit of an annoying tone.

Anyway, I managed to get out in the shop today for a little. I had previously gotten all of the doubler plates and reinforcement forks matchdrilled to the spar, so today was all about prepping and priming.

Here’s W-707F, which sits on the back side of the left spar. I’ve deburred and scuffed it; all I need to do now is dimpled the outboard holes in preparation for attaching it to the spar and outboardmost rib.

I love scuffed parts. They hide my fingerprints.

Here’s W-707E, which is the doubler plate that sits on the aft side of the rear spar, right in the middle. I’ve marked the cutout for the aileron push tube. Where’s that step drill?

Yup, here you can see my fingerprints.

I started looking around for my stepdrill. I spent good money on that stepdrill, but I couldn’t find it anywhere. On the workbench, under the workbench, on the floor, in some other shelves. I thought maybe I put it in some other tool’s case, so I got out the dremel tool, multifunction tool, jig saw, circular saw, etc. Nothing.

I even accused the girlfriend of selling it on the black market to fund an bottle of Opus One. She insisted that while she thought about it, she didn’t.

I remember putting it in this old small cabinet of drawers (that my dad gave me when I graduated college…thanks, dad!). I spent about 30 minutes just pulling out each one of these drawers, looking for my step-drill. Grrr.

After continuing to work on the airplane (angrily) for another 30 minutes, I finally found it when I came back to the drawers and opened them with my other hand. Apparently my sausage fingers (they’re not, I promise…I’m just mad) blocked my view of the stepdrill, which was right behind the lip of the VERY FIRST DRAWER.


Anyway. Back to the rear spar. This is the forward side of the left spar, outboard end. I’ve deburred the edges of the whole spar, and now I’m deburring all of the holes I drilled.

I always scuff the areas where there are holes I've drilled and deburred. Helps me keep the "did I do this already" time to a minimum.

Oh yeah, I managed to get a couple parts primed today. Like riveting, I always feel like it is a productive day if I can prime some things.

You can also see my primer of choice, Napa 7220.

Here’s the other side of those pieces (after plenty of drying time).

I like priming.

Back to the spar, more deburring holes and scuffing.

I'll finish scuffing the whole spar when I get closer to priming.

This is the middle of the rear spar, around the aileron pushtube hole. More deburring and scuffing.

Jeesh, there are fingerprints everywhere.

Finally, I brought the two primed parts back inside.

Primed parts on the workbench always means we're getting close to riveting. Wuhoo!

After this was about when I finally found my step-drill. I was too angry at myself to keep going, so I headed inside to some grilled chicken, jasmine rice, and creamed corn. Mmmm.

1.5 hours

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Countersunk Left Main Spar, Drilled Left Rear Spar

November 13, 2010

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Well, I managed to motivate myself out into the garage a little this weekend.

I only have a few more steps on the left main spar, and the the left rear spar, before I really need to get my butt in gear with the rib deburring and finally build a wing stand.

Today, I focused on countersinking the screw holes for the tank attachment.

Reading back over my own old post (in which I reference some other builders), I found this table. I’ll copy it here, too.

Countersink Widths for Numbered Screws
Screw Size Width [in]
#6 <0.3125
#8 0.365-0.375

So, I broke out my trusty digital calipers, zeroed them out, and dialed in .312.”

Sorry for the blurry picture.

So, with microstop countersink cage on the front of my drill, I got to work. Here are the smaller countersinks for the #6 inspection plate attach screws on the bottom flange of the left spar.

Pretty countersinks.

Then, I moved up to the 0.370″ countersinks for the larger #8 tank attach holes.

Looking good.

Somewhere in here I flipped the spar over and finished all the countersinking on the upper flange of the left spar.


After the countersinking, I scrounged up the left rear spar and corresponding doubler plates.

Left Rear Spar, reinforcement fork, and doublers.

Per the plans, I grabbed the W-707E and aligned it 50 3/4″ from the outboard edge of the rear spar.

I promise it is right at 50 3/4". I think the paralax make it look off.

W-707F is laterally aligned with the outboard edge of the rear spar channel.

W-707F is clamped and ready to matchdrill.

Here’s W-707E, ready to drill.

After drilling one #30 hole.

All done.

Then, I moved outboard to W-707F.

Before matchdrilling.

All done.

I call this the forest of clecos.

I moved inboard and matchdrilled all of the reinforcement fork holes.

A lot of drilling.

I pulled the doubler plates and reinforcement fork off and set them aside.

I still need to drill out the aileron pushtube bracket hole.

Reinforcement fork pulled off.

Next up, deburr all parts, along with finishing any last minute tasks like dimpling where I can’t reach later, then prep for priming, prime, and rivet the rear spar together.

1.5 hours.

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Finished Right Rear Spar

September 14, 2010

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So on the scale from “no help at all” to “girlfriend built the plane all by herself,” we made a few steps last night.

After dinner (thanks Mi Pueblo!), I convinced the lady friend to come outside and help me finish up the last few rivets on the right rear spar.

I talked her through going to the plans, looking at the rivet callout legend, and then putting the rivet in the appropriate holes, making sure to avoid the “rivet later” holes.

We were planning on having her actually squeeze the rivets, but the AN470AD4-6s (and -8s) were too much. She ended up holding the spar steady for me and helping with rivet layout. (See, I told you it was a small step toward “girlfriend built the plane all by herself.”)

I’m working towards being able to call from a business trip across the country and tell her to do something offhand like, “Hey honey. Can you hang the engine for me tonight while I’m away? Great. Thanks. Bye!”

Here's the plans shot for the reinforcement fork.

Of course, we were too busy being in love (with each other and the airplane) to take very many pictures, so you just get the end result. The main squeeze did a great job reaching all of these rivets (mostly due to the 4″ no-hole yoke).

Final rivets in the fork-only area. 38 rivets here.

Closeup of the fork and doubler plate together.

Final rivets in the doubler plate. 7 more rivets here.

Finished product.

0.5 hours (thanks, girlfriend), and 45 perfect rivets.

For those of you paying attention to the totals, that brings me to 175 hours (after 261 days) and 2409 rivets (of an estimated 20,000). Still a long way to go.

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Primed and Started Riveting Right Rear Spar

September 12, 2010

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Well, after a $15 stop at Napa ($10 for primer, $5 for sensor-safe RTV), I got back to work on the rear spar.

I spent a lot of time just kind of staring at everything today. The instructions are careful to point out that at the inboard part of the spar (where the reinforcement fork is), you can’t reach the spar flange holes with dimple dies for later dimpling, so you should do it now.

With that in mind, I wanted to make sure I got everywhere that may need dimpling later, so I also dimpled above the two (middle and outboard) doublers. You can see in this picture (the middle doubler) where I decided it would be a good idea to dimple (drill, deburr, then dimple, of course) the flange holes. I did this for both the spar and the doubler plates, which also have flanges on them.

The middle spar area, shown after drilling, deburring, and dimpling the flange area.

Same thing here. Also, I dimpled the 4 outboard holes (instead of countersinking), per previously approved builders who have talked to Van's.

I got back to thinking about the tank dimple dies, and whether they were really helping with skin-to-structure attachments. The idea is the the tank dies (which are deeper to account for pro-seal while riveting the tanks), when used on the skeleton, allow the regular dimple in the skin to sit better once riveted.

I got out some scrap, dimpled the “skin” with regular dies, and dimpled the “skeleton” with one tank and one regular die.

You can see on the left, those are the regular dies. The ones on the right is a regular die sitting in a deeper tank dimple. The tank dimples didn’t help anything sit better, because they were both fine.

A little blurry, but the "skin" sat equally well for both set of dimples.

The tank (deeper) dimple is on the right. You can see I'm not having any "seating" issues on the left.

Anyway, I think I am going to go back to using the regular dies on everything. Enough about that, though, let’s prime!

The rear spar components, getting primed after some more edge finishing, washing, drying, and positioning in my wood floors boxes.

Also, I went back and masked off the spar where I had countersunk.

Some of the nutplate attach rivets are not as flush as I would like them to be. I may get a rivet shaver and shave some of these down and reprime. We'll see how the tank skin sits on them.

Back on the rear spar, I posted a couple pictures of my edge finishing procedure. First, use the Permagrit block to smooth out the tooling marks. This picture is the resulting burrs that need to be deburred.

The permagrit is great, but it does leave some pretty decent sharp edges.

Then I used my “v” deburring tool to knock off the 45°.

After this, I usually use a scotchbrite pad to smooth everything out.

After blowing the aluminum dust off with shop air and a good wipe-down with MEK, I took the spar outside so I could paint the grass with my overspray.

I think this is the second side. Only one bug landed on my spar. I left him there for now. (He may be my first passenger.)

After a few hours, I returned out to the garage (workshop/mancave) to do some riveting.

First step: Ignore Van’s suggestions to tape off all of the holes that don’t get riveted now. (I know the warning bells must be going off right now, but it all worked out fine. Just have to read the plans carefully.

I left clecos in all of the “do not rivet now” holes. 6 regular AN470AD4-4 rivets on the left, and some AN426AD4-4 (I think) rivets in the dimples on the right.

SEP 14 UPDATE: WHOA! Those 4 on the right can’t be set now, because the W-712 outboard rib will get riveted to these holes, too. Glad I didn’t get to happy with the rivet squeezer.

These 10 can be riveted now. (Sep 14, 2010 Update: Nope. Just the 6 on the left can be set now.)

Same exercise here. Only 5 rivets can be set now.

I didn't really mark anything here, because I didn't really start on riveting the fork on yet. Next post, I'll be very careful about what to rivet.

Then, I actually started riveting. I love my new Cleveland Main Squeeze. Squeezing these An470AD4- rivets is so easy now.

Here are the 5 shop heads from the middle of the rear spar.

The same 5 from the manufactured side.

Oh, and I did 6 more at the W-707F doubler plate, but forgot to take pictures. 11 total. Also, I was mixing this and house projects over the course of a few hours, so I’m going to estimate it was about 2.0 hours today.

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