Saturday, June 19, 2010

That "Substantial Penalty for Early Withdrawal"


I'm back from the future to tell you something important:

RUN to the phone and call Van's. Place an order for:

FOAM 1/16x1/4 V1110 (4" length, if they ask)

Then go download Page 31-13 from the Archive Pages on Use that page to install the wireway. You won't be able to install the bracket until you do the rudder pedals, but those are coming soon. You will be happy to have this done when you get to page 31-13, trust me.

Don't believe me? Then take a look at this.


You know that substantial penalty for early withdrawal warning you always hear tacked on in the verbal fine print of financial commercials? Well, that's not the only place you'll pay such a penalty.

This morning I finished match drilling and riveting the engine mount brackets to the tunnel walls. The plans have become somewhat cagey with any indication as to which way the rivets should go through the holes. I figure if Van's doesn't care, well, then neither do I. I decide based on the following criteria:

  - Which way is easiest to get at?
  - Which way will hide the wart-like shop head from sight?

If those both happen to coincide, it's an easy decision. Such was the case with the engine mounts. Not only was it easier to rivet through the tunnel sides, it also put the ugly part of the rivets inside the tunnel where they won't be visible.

I then clecoed the tunnel walls, lower firewall, and corner pieces together prior to riveting. 

This was going to be a large enough riveting job to warrant a trip to the hangar. I had to go to Lowe's anyway to pick up a roll of replacement screen (follow that link - it's worth it!) to fix the back porch sliding door anyway, so it was no extra effort to stop by at the hangar on the way. It's something like ten times faster to rivet with the air rivet puller and a hundredth the effort, too, so it was a very simple decision.

What I failed to account for was coffee-speed. Having just finished my morning quart, my brain was firing on all eleven cylinders (most brains only go to ten). That's okay, for the most part, but it can cause problems when attempting to synchronize with the more physical appendages. For example, my hands. My hands, unable to keep up with the blazing speed of my caffeine-addled/enhanced thoughts, tend to either fall behind or rush ahead in hopes of keeping up. This is how I ended up pulling the air riveter away from the rivet in mid-stroke of the internal workings of the rivet puller. I knew something was wrong when I didn't hear the normal "bang" of the rivet mandrel breaking loose and the rivet being set. The gaping hole in the middle of the rivet head didn't look right either. I was sure something had gone horribly awry when the mandrel didn't pop out the front of the rivet puller.

What had happened was that the mandrel didn't break. It actually just pulled through the rivet (without actually setting it - it needed to be drilled out) and jammed in the rivet gun. It wouldn't come out the front because it was still clamped into the inner workings of the rivet gun, and it couldn't come out back either for that reason and because it still had the bead on its end.

I had to disassemble the rivet gun to un-jam it. That wasn't very hard to figure out, although it was something that I was nervous about. You never know if little parts will fall out or a spring will launch itself when the restraining parts have been removed.

It did both.

All told, it took about twenty minutes to get it all put back together and working, Now, you'd think that having learned my lesson about letting my hyperactive brain set the pace, I'd be careful to not let that happen again. As much as I appreciate your confidence in me and my ability to learn a lesson, I have to disappoint you. It wasn't a dozen rivets later before I did the exact same thing.

The last step in the riveting job was to rivet the lower fuselage to the tunnel side flanges. This one was a little tricky. While it appeared that riveting through the firewall and into the tunnel flanges would satisfy both of the decision criteria detailed above, there was the matter of a collection of holes in the front of the firewall that had met whatever arcane criteria is used by Van's to decide whether or not to use their only-when-we-feel-like-it dimpling tool. If those holes needed to be dimpled for flush rivets, why don't the rest of them? But if I riveted from the other direction, they'd be even less flush - the wart heads would be out there for all to see.

I riveted through the firewall. I figure those flush rivets will sit under another part (say, the engine count?) and therefor need to be flush while the surrounding rivets do not.

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