Sunday, August 29, 2010

Biting the bullet

I had put it off for as long as I could. I have looked at them from every possible angle, agonized over whether or not I had them bent just right in all three dimensions, found other things I could do to further postpone the decision to commit to drilling them, and finally reached a conclusion: it was time to bite the bullet and match drill the longerons. There was nothing to be gained by putting it off any longer.

An excuse I had been using was that I didn't have a suitable piece of scrap to use as a stunt double for the side skins, but I found just such a piece while searching the shop for something unrelated. I also found the missing fuel nipple that gave me such grief. Typically, I did not find what I was actually looking for.

The first step was to get the scrap faux-skin clamped to the longeron.

Then the canopy sill was clamped on such that its edge was overhanging the faux-skin.

In order to have any kind of stability at all for the impending and ultra-critical drilling operation, I had to find a way to hold the assembly in place on the workbench. I clamped it to some of the left over 2x4 scraps from the construction of the workbench.

With the traumatic memories of the 71 hole drilling marathon of the center section still painfully fresh, I dreaded drilling through the longeron material. I needn't have worried. I loaded one of the brand new #30 drill bits that I had purchased from a tent-dwelling huckster when I was at Oshkosh. Truthfully, I didn't see how these bits could come anywhere near the lofty promises that guy was making, but I have to admit that I was wrong to doubt him. Hot knife, meet butter. Those bits tore into that aluminum like a Doberman into a pound of bacon.

Even though the longerons will have to come back off for deburring and priming, I went ahead and clecoed them onto the fuselage just to make sure everything fit.

Once they're cleaned up and primed, I'll be just about ready to rivet on the side skins. Before I do that, though, I'm going to do a thorough audit of any holes that don't yet have rivets in them to make sure that I haven't missed the step that would have filled them. Things are going to start getting a little harder to reach once those side skins go on. 

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