Thu Jul 2 2009

Riveting aft deck

Today we spent the morning riveting the aft deck to the fuselage. I thought this was going to be really easy because I was so meticulous in ensuring the fuselage had no twist before I match drilled, but after riveting the F-709 bulkhead to the aft deck, we laid it atop the longerons and the holes were slightly off. After much head scratching, clamping, and unclamping, we decided to insert loose rivets along both sides of the deck, then I untwisted the fuselage while my dad clamped the deck to the longerons. We were able to get it to within 1/4 bubble (about .001 inch per foot twist), then started riveting. While squeezing some of the rivets, some twist came back and we ended up with about .005 inch per foot of twist. That's only .024 degrees, so it's significantly better (roughly 5X better) than you could get with a Smart Level. Good enough!

Next, we decided to work on installing the gussets behind the F-706 bulkhead. After using the new 1/8 pop rivet dimple die to dimple the leftmost hole, we clecoed and clamped it in place.

I noticed, however that the F-706 bulkhead was very flimsy and allowed significant forward/aft movement of the gusset along the longeron. So I used a piece of oak clamped both below and above the longeron to straighten the bulkhead in preparation for drilling. It worked great.

Unfortunately, when I drilled the left side, I forgot to use the aforementioned oak strip and drilled to the longeron in the wrong position. Arg! We found the holes were over 1/8 (maybe as much as 3/16) too far aft. Double arg! The solution was to fabricate a replacement gusset then match drill through the bulkhead and the longeron from below. It came out great. The worst part was wasting an hour remaking the gusset.

After priming the gusset and riveting them both on, we riveted the stiffeners to the arm rests. Came out very nice!

We also primed the inside of these end caps which I had forgotten to do yesterday.

Upon installing the first one, we found that it was rather tight due to the primer buildup, so I tried tapping it in with a mallet. Actually tapping isn't the correct word. It ended up being some medium pounding. The problem came in when on one mallet blow, it went past the point where the holes lined up. We spent about a half hour trying to figure out a way to get it back out before we gave up. Sigh. Gonna have to work on this some tomorrow. Maybe I'll check with my brother...he's come up with clever solutions before...I bet he'll have one this time.