26 Oct 04 - Finishing the Tunnel Cover

The goal for tonight is to finish fabricating the tunnel cover. It's got to be match drilled, deburred, dimpled, etc. . . all the normal stuff. let's see how we do.

Because there are already nutplates in the floor, we decided that match drilling it like this was best.
There's the top piece on there.
Match drilling the pieces.
Now it's in place, let's pull it out to drill the rest of the holes.
This is going to require more comments to clarify, see below.
And this will too. Keep reading.

A few things are worth noting at this stage:

  • We weren't sure whether to dimple or coutersink the top plate. We decided to dimple it because technically it's thin enough that you can get away with it. This wasn't a good thing, as we couldn't get the dimpled piece to fit to the tunnel cover sides even after countersinking them. The only way to get it to fit would be to countersink it enough that you're removing a whole lot of metal, and then the rivets wouldn't have fit. Conclusion: it would be best to countersink the top cover, but we've already dimpled it, so what do we do now? The above center picture illustrates how we used a grinder to get rid of the dimples on the other side, so it would fit against the tunnel cover sides. It's not quite flush, but it's close enough. I really think it's a better idea to just countersink the top and be done with it - you've got to remove metal from somewhere, and that will really simplify things in the long run.
  • Also, we wanted to back rivet the rivets in the tunnel cover, but they are so close to the edge that the typical Avery back riveting set can't get in close enough, so we ground off the "nose" of the rivet set. Works fine now, but now the tool doesn't look all that hot. I'm not sure if there's a better solution for this, but this worked well and the tool, while ugly, still works just fine.

Riveting with the modified back riveting set.
Finsihed! Well, sort of.

It turns out that this isn't quite done - there's one more screw that goes in the front of this. We've got to match drill a hole in the seat floor and then put a nutplate in, but as this will involve pulling the right forward seat floor out, we'll put that off until tomorrow.

On the plus side, the work that we did today was the first real reason that I've had to sit in the plane, other than just sitting in there for the purpose of making airplane noises. That was fun.

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