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.

Sweet.

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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Primed Elevator Trim Tab

August 19, 2010

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Well, I got a few more things done on the tab tonight.

First thing was to prime the outside of the elevator tab where the surface mates with the tab horns.

Here's the mating surface, ready to be primed.

After reexamining my countersinks in the trim tab spar, I decided to re-countersink them. This time (after reading the guidance in the construction manual about how to do this on the flap), I used the trim hinge as a countersink guide. This worked much better than the piece of wood.

Nice countersink on the left. The old (wobbly) countersink on the right.

Then, everything was put up on the cardboard piece for priming.

Priming.

After the parts dried, I started in on riveting per the plans.

Everything was fine after 7 rivets, until I paused to re-fit the tab on the elevator.

4 of the first 7.

I was getting a little bowing (top skin concave, bottom skin convex) in the tab skin due to what appeared to be distortion of the tab spar. I drilled out the 7 rivets I had set and spent a little time re-tweaking the spar.

A fit check. You can't see any of the bowing very well, but it is definitely not satisfactory.

After re-tweaking (adjusting the spar flanges on the tab) and refitting a few times, I had things lined up much better. It’s not perfect yet (maybe more work on this tomorrow will get it right), but it is definitely improvable.

1 hour today.

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Riveted E-705 to Left Elevator Spar

July 6, 2010

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Well, I thought I would head out to the garage tonight to rivet 4 little rivets. I had the parts primed from the other night, and I just wanted to get something done on the plane tonight. I grabbed the elevator spar and admired how nice the countersinks looked.

Looks like I didn't get total coverage there on the spar, but that's okay, a light coat is all you really need.

Here are the AN426AD3-3.5 rivets that will go in those four holes.

Here's the first one set. Pretty nice, if you ask me.

I got the other outboard rivet set, then moved to the two middle rivets. Then, tragedy struck, and my flush squeeze set slid off part of the rivet as I squeezed. Boo.

"Well, this will be easy to drill out and replace." -famous last words.

My drilling wasn't perfect, but I didn't booger up the hole too badly...yet.

After resetting, I thought all was well, until I turned the part over.

That's not really flush, is it.

After 6…yes…SIX times of setting and drilling out a mis-set rivet, I finally gave up, drilled the hole to #30, cleaned up the countersink, dabbed some primer in the hole, and used an oops rivet.

OOPS! (Looks okay, though. And you will never see this.)

I can’t believe I had to drill out six rivets when trying to rivet four little AD3-3.5 rivets. Bummer. That’s not going to help my batting average…[calculator sounds]…yup…went from 5.7% drilled out to 6.0% drilled.

A frustrating half an hour tonight.

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