Over the past week the F-01412A and F-01412B Bulkheads were prepared, match drilled, dimpled and the tie down bracket drilled, countersunk and primed. With these steps completed the parts were riveted together, but not without stupid issues. A #12 drill broke off in the vertical stab. I noticed I wasn't making any progress drilling, plus I was starting to ruin the hole. Then I took everything apart and saw the end of the bit lodged in the vertical stab. After removing it, I enlarged the hole (so as not to deal with a damaged hole) to accommodate an AN4 bolt and moved on. Also, after riveting the tie down bracket I noticed two adjacent dimpled holes. The instructions clearly indicated to dimple. My bad, I should have checked closer and fixed the issue. Oh well. (I may just order new parts and do this over.) With this mess behind me I moved on to the F-01411A and F-01411B Bulkheads and the attach bars. This went totally smooth and all the rivets were set without issue. I decide to wait until later to flute the lower flange. To end the day I final drilled to 1/4 inch, the F-01410C Horizontal Stab Attach Bars.