Today I begun by refluting some of the ribs. Then I begun drilling the wiring conduit holes. The wiring are used for naviagtion lights, landing lights, antennas and even maybe an autopilot servo.
Van's is suggesting either to enlarge a tooling hole or to drill a new hole in the lower part of the web. The two positions are marked on the picture below and I decide to drill both, we'll see later how I will use them.



The tooling hole enlargment is easy, the second hole is a bit more tricky. We want the holes to be aligned but the ribs come in different flavors: different length, some have the flanges looking right other have them looking left. On a builder's website, I found a nice and easy method: the idea is to build a small jig that will be aligned on fixed marks on the rib.
With some aluminium crap, I fabricated the small jig visible on the picture. The lower edge of the jig is aligned with the lower edge of the rib and the corner marked H is aligned with the rim of the second lightening hole. As all the second lightening holes are aligned, the jig gets a fixed position on the rib. On the picture, the jig is placed on a "left" rib, the hole has been backdrilled from the first rib.



On this picture we have a "right" rib, the jig has just to be flipped over to drill this type of ribs.



Then the holes get drilled to 3/4" with a step drill, this is straightforward.



Here is the result with the ribs assembled to the spar, looks pretty straight to me.