Bottom wing skin priming and lap joint

I've been very slowly making progress on the bottom wing skins - slowly mostly because of weather not allowing me to prime parts repeatedly for the past few months (below 59˚F which is the minimum for Akzo).

When I got a chance, I primsed many of the smaller parts that were lying around, like the inspection covers and the pitot tube attachment parts:

Primed pitot mount and access cover parts
I riveted the L-shaped bracket for the pitot tube:

Pitot mount bracket
I then got to the dreaded lap joint, which requires tapering the ends of the skins so they overlap properly. I started by testing on a scrap piece, and got OK results with the Dremel:

Simulated lap joint on a scratch piece
I then moved to the real outboard skin for the right wing:

Section of the outboard wing skin which overlaps with the inboard skin
Being much larger, it soon became clear that the Dremel would not suffice, so I got a random orbital sander, which did the job (not without a few hours of effort to get that tip to half the thickness and a smooth ramp in):

Sanding the edge of the outboard wing skin for the lap joint

Wing skin lap joint thickness
Wife primed that skin and I dimpled it:

Right bottom outboard wing skin, primed
Being a quickbuild kit, the inboard skin was already riveted on, so that was more difficult to sand and prime:

Overlapping inboard skin area which overlaps with the outboard skin
After a few hours of sanding (switching between the Dremel, the orbital sander and a sanding block), the end result is quite decent, and the lap joint looks flush:

Lap joint after sanding
Next is priming the inboard skin strip that got sanded, and repeating it all for the left wing, then finally riveting those skins in place. This week's weather promises some significantly warm weather, so that should happen soon :)

Time lapse:

Total bottom wing skin rivets: 433
Total bottom wing skin time: 54.1h


  1. Saw your bottom skin problem on Van's Air Force. Did you use paint stripper or metal prep
    on the lap? Looks to me like corrosion on the bottom of the skin.

    1. All I used was primer (Akzo 463-12-8 after mechanical etching with Scotchbrite+Prekote).

  2. What was Van's solution for your lower wing skin problem?

    1. Either filling the crack with JBWeld or cutting off that corner, which is not structural. I'll have a dedicated post about it.