[October 13, 2006]

I was able to jet out of work today way early because yesterday I was in NYC and had to wake up at dark-o-thirty, for a 16 hour day of mostly commuting. Anyways, the first thing I did was countersink all 120 tank attachment holes. This process went way smoother than I thought. My process was to do the initial countersinking with the air pressure at 40-50psi, then go back one last time to all of the holes with the drill at 90 psi. Results were pretty good. I didn't get any chatter marks, but it wasn't perfectly smooth either. There were some small rings around the countersunk hole.

Next I installed the inspection cover nutplates and countersunk them with a #40 bit. This was super easy, but I did catch two instances where the countersink bit wandered a little and I had 2 holes that had some chatter for it. I didn't want to clean up these chattered holes because they were the perfect depth. They aren't structural, so it doesn't matter.

One thing to be sure you do here is countersink for a #6 hole. The inspection plates use #8 screws, EXCEPT on the side of the wing spar, due to if they did use s #8 here, then the countersunk hole would be off the side of the spar.

Next I installed the two nutplates on each web of the spar. a 3" yoke just barely was able to reach them. I think I am done with nutplates on the spar FINALLY. Let me just tell you that it took forever to get through all of the nutplates and countersinking on these spars, and you really don't have all that much to show for it. 74 nutplates, 148 rivets and 220 countersunk holes PER SPAR. I am super glad to be done with this.

Next I started to fabricate the tie down bracket stand off's by drilling 1" holes in some AL stock. I had a 1" metal hole saw that I used. The first hole turned out to be 1/32" off center. At first I was mad because I don't know how it wandered, but after I sat down and had a beer, I realized it didn't matter because all it does is provides a standoff. Its not like it is being yanked in compression or stretched. Plus, it sits behild the tie down bracket tucked in the wing. I need to remember that I am just building an airplane and get over this small crap, and worry about when I really mess up.

Mounting the nutplates for the inspection panels.

I ran the scotchbrite wheel over the edges of the inspection panels. Then I drilled the #6 screw holes along the straight edge, and dimpled.

A quick reminder to let me know down the road that not all of the holes are #6's.

Testing the countersinks I made. Just a little more needed.

#6 dimple Countersinks on the spar.

Finally, the last two nutplates on the spars. Unless you've done this before, you have no idea how good this feels to get through the all of this countersinking/nutplate BS.



Last Modified: June 20, 2024