Initial Prep (Debur, Trim, Drill, and Cut)
11/17/2021 – 2.7 hours
11/18/2021 – 1.1 hours
11/19/2021 – 2.4 hours
11/20/2021 – 2.4 hours
11/21/2021 – 0.8 hours
11/22/2021 – 3.8 hours
11/23/2021 – 1.0 hours
11/24/2021 – 3.7 hours
11/28/2021 – 3.5 hours
12/1/2021 – 2.2 hours
12/2/2021 – 1.9 hours
12/3/2021 – 2.3 hours
I started this step by separating the flap hinge ribs and parts for the torque tube support assembly. The band saw made very quick work of separating the parts, and I filed the cut areas smooth to finish the parts. I also took the opportunity to debur the edges on the parts (holes will come later).

My attention then turned to the ribs. At first glance, the pile of ribs on the workbench is daunting. There are 28 total ribs (14 for each wing) to debur, drill, dimple, flute, and prime. There are three different types of ribs, left and right versions of each type, and the direction of the rib flanges change as you work down the wing – some face left and some face right. Finally, the bottom of the ribs has a separate single-hole flange at the aft end. That was a critical clue for me to ensure I had the ribs ordered and oriented properly. I used the final two drawings in this section of the plans to separate the ribs for each wing and to order them in the same way they'll be installed.

Proper preparation of the rib flanges is important to a quality job on the wings, and I felt it was worth a modest time investment to make them as good as I could. Deburring the edges of the ribs is pretty standard at this point. I'm not a huge fan of the large Scotch Brite wheel for parts that are relatively thin (like the ribs), so I decided to use Dremel sanding wheels and maroon Scotch Brite flap wheels in an electric drill for most of the deburring tasks. After deburring the edges, I checked and adjusted the flange angles to make them 9- degrees to the rib webs. Most adjustments for me were on the forward flange. There were also a few flange tabs that didn't quite get formed properly at the factory, so made some minor tweaks to straighten them up as well.

I decided to save the fluting step for later – after all of the final drilling and dimpling is done. I didn't need to final drill any of the #40 holes in the rib flanges since they were already final sized. I checked them all with a drill bit to make sure. I finished the flanges through this stage by deburring all of the holes. I also took this opportunity to cleco the torque tube bracket assemblies together to final drill and debur the common #30 holes.
[Band Saw, Dremel, Files, Hole and Edge Deburring Tools]

Final Prep (Dimple, Countersink, and Shape)
12/5/2021 – 4.4 hours
The plans call for only the holes on the lower rib flanges to be dimpled at this time. Logically the top will have to be dimpled, too; and later in the plans they are – but after the ribs are attached to the spar and bottom skin. I'm not sure why both top and bottom aren't dimpled right away, but I stuck to the plans and just did the bottom flanges as specified. There are also a couple of holes in the bottom of each aileron torque tube bracket to dimple. After I finished dimpling, I worked on filing a radius on the upper and lower edges of both torque tube support brackets. I used the large Scotch Brite wheel for this task, and I feel like the radius task went well. I'm not happy with how the brackets nest inside the ribs, though. The issue is the brackets are just a bit longer than the rib web, which makes for a very tight fit and will make riveting very difficult. I'll have to look at this some more to see if I can / should improve the fit. I finished this session by fluting the flanges of all the ribs. I didn't need to do any fluting on the aft flanges, but almost all of the forward flanges needed some work.
[Pneumatic Squeezer with #40 Reduced Diameter Dimple Die, Bench Grinder with 6” Scotch Brite Wheel, Fluting Pliers, Marble Flat Surface]