Picking up where I left off I get the J-Channel prepped for the next spar. This time I decided to pre-mark the 1/16 depth on the J-Channel to mark the alignment vs using my digital Caliper. Pulled out the edge-marking guide I purchased from Cleveland tool and made quick work of it.
Basically a rinse-repeat of the previous update and quickly got the J-channel match drilled and set aside.
Next step was to get my countersink set up to make the appropriate cuts on the spar. Reading the directions, it took a while for me to fully understand what was being described in the text. Basically for ALL the nutplate rivet holes, you countersink them to just flush with the rib flange. (also there are a few additional rib attachment holes between the nutplates that area also just countersunk flush. Being slightly nerve-wracking I started SLOW and checked each countersink till I got more confident that I was doing things right. (As always I started with a TEST piece before I worked on the spar!)
Once both spars had this level of countersunk done (13-3 step 2), I reset the countersink to accommodate skin dimples and begin to countersink all of the remaining holes in the spar flanges (13-3 step 3). Easy enough and using a good countersink cage really helps to ensure you don’t screw up.
Once everything is countersunk, time to start installing the nutplates for the tanks. Again, nothing technically difficult but did take the time to make sure that my rivets really sat flush prior to squeezing. If they were just slightly proud, a turn or two with the deburring tool fixed the situation. (Also plans don’t call it out but be sure to deburr the inside edge of the spar web)
I ended up skipping 13-3 step 5 for now since I didn’t have the right countersink (on order currently) and moved to installing the nutplates for inspection plates. Again, nothing difficult.
EDIT: Before you laugh at me, I totally misread step 5 and ordered a #19 piloted countersink. Plans clearly state to “Drill a #19 hole and dimple for #8 screw. Countersink with a #30 piloted countersink.” Oops.
Note: Before I started to countersink on the inspection plate nutplates, I couldn’t understand how they interacted with the J-stiffeners. Finally looked ahead only to realize that the J-Stiffeners do not mate to the spar, but get inserted into the ribs. The Spar was just used as a Jig. Again, why it pays off to re-read everything and if you don’t understand something, just stop working and keep reading till you do 🙂
Next up I again adjust my countersink set for 13-3 Step 7 to countersink for the inspection plate dimpled skin. First, this is a DEEP countersink. Deeper than I would have naturally attempted, but I followed the directions and took measurements per the plans.
Somewhere in here as I was trying to figure out next steps, I ended up tapping the tie-down holes, pulling the Ribs off the shelf for the next chapter, and taking some mental notes on what I want to do next. I still need to re-adjust my countersink set back to put the nutplates into the Spar web area, cut and drill the tie-down brackets, and finish the last few items on the Spar. Hoping to get this all done this week so I can start Ribs by this weekend.
Non-building related, I was able to fly up to NJ on 1/26 with my kids. Flight up was great and had a wonderful time visiting with family. The flight back was a bit of a slog. A 30 kt headwind made for a long trip home and a nice “sporty” landing into VKX. Once again my kids were total troopers even with the low-level turbulence once I was in the SFRA / FRZ. With the weather hopefully starting to improve I’m hoping to start flying with some local friends to work on getting some hood time and acting as safety pilot. I may yet get my IR rating before the end of the year!