<October 25, 2005>
Wing Spar Countersinking, Priming & Tie-Down Stuff
Another good night in the shop tonight. I started by installing the two K1000-4 Nutplates on the front side of the spar, then I primed the countersinks, and I finised up the night by starting on the tie-down brackets. Quite the variety tonight.
When I took out the K1000-4 nutplates, I didn't think they looked so good compared to prior nutplates, so I cleaned them up and shot them with a light coat of SEM Self-Etching primer. The SEM is new for me, and I think I like it.
Here is where the nutplates go. Make sure you study the plans good, you wouldn't want to countersink the wrong side here. Don't take my word (pictures) for it... look at the plans yourself!
I was surprised to see that my 3" yoke reached this rivets with only about an 1/8" to spare.
Rather than dabbing primer in each countersunk hole, I just taped of the spar flange (the section with countersinks) and sprayed away. I think it looks better than primer splattered all over and it only took a few minutes to do. I could really get used to this SEM rattle-can primer.
I started the tie-down brakets by cutting the aluminum bar into the perscribed 2" sections. Actually, I cut them maybe 1/32" long because finishing the edges on these pieces will take that extra off... follow me? I needed another clamp to drill the holes in these so I put them aside until tomorrow.
I then turned my attention towards tapping the tie-down brackets for the tie-down ring. The 3/8"-16 tap from my el-cheapo Harbor Freight Tap & Die Set worked great. I don't think I have tapped anything since high school metal shop but this turned out to be really easy. I seem to remember the procedure being to turn the tap one whole turn, then backwards 1/4 to 1/2 turn, then repeat, forward a whole turn, backwards 1/4 to 1/2. Tapping both only took 20 minutes.
Fits like a glove!