February 10, 2008

I finally got around to making the channel nuts for the tail section. I had previously tried to make them out of aluminum sheet but it was difficult to get a sharp bend without the proper tools. I found pre-made aluminum channel at the local hardware store that is made to fit 3/8" bolt heads, so I just used that to start with.

I measured out and marked where the bolt holes go as well as the middle screw hole first. To make sure the bolt holes would be in the right place, I used a 3/16" transfer punch through the actual hinge that I was making that particular channel nut for to mark the center of the hole. Then, I drilled the holes for the bolts and the screw. It took a little but of trial and error but it seemed to work best when the channel nut bolt holes were slightly oversize. Another builder pointed out that this will help when I'm installing them with the hinges on the spar so the bolts will pass straight through the holes in the spar. We'll see how they fit when I'm installing them, I may need to make some over again.

After the bolt holes were drilled and things fit together. I slid in the bolts and crimped down the sides over the bolt heads with a vise. The screw still has to fit in the center so I tried to only crimp around the bolts. On the smaller ones, sometimes I had to bend back the middle so the screw would fit. I used vise grip pliers for this. The walls of the channel was too tall, which is good for crimping but after that, I cut off the extra wall material with the bandsaw. All this cutting and bending really scratches up the aluminum so after all the channel nuts were made, I used a 3M polishing wheel to polish up the surfaces.

I spent a lot of time over two days doing this but that's all it took. I'm having a little trouble tracking down the right tools to rivet the AD5 rivets on the hinges so that's taking a little bit longer but I'm looking forward to moving on to the tail assembly now. Here are all of the channel nuts for the tail.

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