Sunday, May 2, 2010

Rolling along...

This morning I riveted yet another brace to the posts that hold the bushings that hold the pins that hold in the wings that will hopefully reliably hold my fragile skeleton aloft over central Ohio.

Oh, and I met an old lady that swallowed a fly. I won't go into why she swallowed a fly...

The directions for riveting in the braces insisted that four holes remain free of rivets. In light of my utter and complete failure to do so with a rivet hole yesterday, I've applied another layer of protection to my reminder process:

Clecos with duct tape! If that doesn't do the trick, nothing will.

Note also that I have started a new practice: I also put a few rivets in along with the clecos because they are just ever so slightly thicker than the clecos. They force the parts into the exact alignment, rather then the almost exact alignment provided by the clecos.

With the brace in place to hold the posts rigid, the only remaining thing to do in that area is to install the rollers that the wing spars will (see if you can guess.....) roll across as they are slid into the side of the fuselage.

That was all fairly routine, but the next step was anything but. I've assembled any number of bearing assemblies thus far, and it is not unusual at all to have one side of the assembly countersunk for a flush rivet. This time, though, I had to countersink both sides and do a "double flush" rivet. Sorry, no pithy comment on that will be forthcoming. It's a target rich environment and I just don't trust myself.

I had to look up what it meant and more importantly, how to do it. Basically you just squeeze the ever-luvin' stuffing out of the rivet and it will (in theory) end up being flush on both sides. The second countersunk hole is to provide room for the shop head (the one I squeeze) to expand.

I can't say that it worked all that well.

There's only so much squeezing for me to give, alas.

If push comes to shove, I'll grind them flush with the Dremel. You know how I am with the Dremel: just give me an excuse...

Next was what should have been a routine separating and marking of parts. You know what happens any time I say "should have been," don't you?

Here's the directive:

Here is the "raw" part to compare against:

Note the relative positions of the holes that I labeled '1' and '2' with the holes in the hatched are of the drawing. Looks just right, right? But you also have to consider the "THESE TWO SETS OF HOLES SLIGHTLY FARTHER APART THAN THE OTHERS" statement. Because it is so very explicit, it is the only choice for determining the correct orientation of the part. The problem was, I couldn't see any difference in the spacing, at least not definitively enough to overrule the bias introduced by the overwhelming certainty that I was correctly gauging the relative positions of holes '1' and '2' - pretty compelling evidence in my book.

I needed to consult an expert for a tiebreaker. I called in Mr. Micrometer.

According to him, holes '1' and '2' were to be ignored. I'm glad I asked!

This is all in preparation for putting together yet another bulkhead. This one will require drilling with a Uni-bit, and I keep that particular device at the hangar. It will have to wait until tomorrow.

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