Brief Description: Drill remaining 3/32" holes in bottom skin
1. Continue drilling 3/32" and clecoing the ribs to the bottom skin.
2. Drilling technique:
- Use light pressure to avoid pushing the rib flange away from the skin--I used the weight of the drill.
- Drilling through the .025 ribs, the bit would cut very slowly for about 20 seconds, then it would begin cutting faster and start throwing lots of small chips, within 5 or 10 seconds it would penetrate the rib.
- Taking advantage of this pattern to minimize fatigue, I could hold the drill very loosely until the chips started flying after 20 seconds or so.
- Then I would use both hands to support the drill so that I wouldn't lose control when it penetrated the rib.
- It took ~40 seconds to drill each hole. That did not include the time required to push or pull the rib into position.
3. I did not drill the new pilot holes for the the main spar. I did remeasure the rivet line for the holes in case clecoing the skin tightly to the ribs pulled the skin further forward. I found that the maximum displacement of the skin by the drill/cleco process was ~1-mm.
4 Completed drilling the holes into the ribs and then drilled the undrilled alternate holes through the rear spar.