Monday, October 18, 2010

Seat backs

You'd think the seat backs would be pretty simple parts and hardly worthy of an entire section in the plans, but such is not the case. They don't seem like much; all they do is provide a surface to support your back when you're sitting in the plane. But wait! They have to be removable, adjustable, strong, and it would be nice if they'd pivot forward to give access to the baggage area behind them. So they need to be at least moderately complex, right?

Well, no. They're pretty easy. Or should be, anyway, but we all know how these things go.

It started out well. All I had to do was cut the corners off of some hefty piece of angle aluminum. This is the kind of job that always endears the band saw to me in an awkwardly emotional way. I simply don't have the words to convey just how important this saw is to me when it comes to cutting thick metal in an almost straight line. I tear up just thinking about it. Just look how easy a job like this is with a band saw and think about the horrible alternative: using a hack saw.

Oh, the horror!

Just look at that! Look at the ease with which I was able to make such a beautiful cut! Why, there's nothing that saw can't do!

Oh, wait.

Yes there is.

It can't cut this:

Well, it could, but not where I need the cut to be. I felt so... betrayed. Abandoned. Cast aside like an easy prom date. In a desperate search for a rebound relationship, I tossed away my pride and returned to the saw that had done oh so much wrong to me in the past. The very saw I swore I'd never touch again. The hack saw. Why, even its name is repulsive to me. Hack! What kind of brutal name is that??

The shame that I felt - it was horrible!

Then, just a few short moments later, all was forgiven. Here was yet another of those situations that just screamed for the flexibility of the wonderful band saw. The idea was to cut the center hoop out of these hinges.

Piece of cake!

Once the center hoop was out of the way, a #30 hole was to be drilled in one of the corners. It would be used to hold the hinge against the part to which it was ultimately to be attached while the remainder of the holes were match drilled. I have a scrap of wood that I use to drill into to keep the bit from cutting through the blanket on my work bench. Apparently a vandal had gotten into my hangar in my absence and left her mark on my drilling board.

Awwww. Isn't that sweet??

It didn't stop me from adding new holes to the board, though. Ya gotta be tough to survive in my shop!

With the first hole drilled, I clecoed the hinge onto the part. It was ready to be clamped and match drilled.

There were more hinges to be cut, drilled, clecoed, clamped, and drilled some more. There were two that went into the seat backs about a third of the way down from the top. These were harder to clamp since they were so far from the edges, so I cleverly grabbed a piece of scrap 2x4 to support the seat backs and hinge together as I drilled through them.

That was one of those brilliant ideas I get that work fabulously right up until the moment that they don't. I guess I should have used a little longer piece of 2x4. Can you guess where the edge of the 2x4 was?

With thoughts of expensive shipping charges for a piece of replacement hinge running through my mind, I took the mangled part over to the vise to see if I would squeeze it back into shape. The vise got it close to straight, after which I made final adjustments just as if it was a tiny, easily bent longeron.

Clecoed back into place, you can hardly tell that it had been molested by an incompetent klutz.

Everything having been cut, drilled, clamped, drilled, mangled, de-mangled, and clecoed back into place, it was time for the riveting. This was one of the rare cases when Van's had a strongly held opinion on the topic of rivet direction. They insisted that the manufactured head be on the outside.

Those get set aside while the seat backs themselves get those hefty angle braces from the first step clecoed on. There were rights and lefts and fronts and backs involved, it was starting to get dark, rainy, and cold all at once, and I was hungry. Not to mention emotionally drained. I figured it might be a good idea to head home and come back for the final riveting when I could take a fresh look at the assemblies and make sure everything is where it belongs.

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