Finished Countersinking Right Spar Flanges

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Well, tonight wasn’t a long night in the shop, but it was a good night.

First of all, there was a package sitting on my doorstep when I got home from work. After the excitement for my new Cleveland Main Squeeze died down as I realized the package wasn’t from Cleveland Tools, it quickly came back when I realized it was the missing W-712-R ribs that I had been shorted (what a cruel world!) in my wing kit.

Who knew I could get so excited about wing ribs.

Drumroll please!

{Triumphant music}

Okay, Andrew. Time to settle down.

Let’s finish up this right spar flange countersinking.

From the first issue of the 2005 RVator (thanks to Brad Oliver, for the link) and to A VAF Post (again, thanks Brad), I was able to make this cute little HTML table for you.

From the first 2005 issue of the RVator (page 10):

We countersink until the top of the screw is level with the surface, then go 2 clicks deeper on the microstop. The actual outside diameter of the countersink measures .365″ to .375″.

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 .370″ (right in the middle of 0.365″ and 0.375″).

Just for kicks, I thought I would show you how much bigger that is than a #8 screw. The larger size allows the dimpled skin to nest nicely in the countersink.

WHOSE TOES ARE THOSE!?

SOMEBODY’S TOES KEEP GETTING IN MY PICTURES!

Anyway, I proceeded with countersinking the tank skin attach holes only (the access plate attach holes are smaller.) I am following the directions here exactly, using a #30 piloted countersink (which nestles nicely in the #8 nutplate) as my guide.

I stopped and verified the countersink depth every few holes. Looking good!

About halfway done with the bottom flange.

Here’s a countersink for your viewing pleasure.

The rivet on the right doesn't look flush, but it is. I promise.

Finally, I finished with the bottom flange. (Notice the three sets of four countersinks on the right side of the picture. Those are for the access plates. They use a #40 piloted countersink and are countersunk to a width of 0.312″ (which is less than 0.3125″)).

Ta da!

Oh yeah, now I have to do the other side.

With a noticeable lack of in-process pictures, I finished the top flange also.

Ta da! (Déjà vu?)

1.0 Countersinking-filled hour tonight.

And, I’ve finished the first three paragraphs of the wing section of the manual. Score!

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