June 23, 2005

Let me start out by saying what a fortunate twist of fate last weekend's frame making mess was. First, I learned how much glue I need to mix depending on the number of strips I'm using and how long they are. Multiply how many strips you have by how long they are and I call this number, "strip-feet." The amount of penacolite resin I need (in grams) is 4 times as much as the strip feet number. I usually add 5-7% more resin to be sure. Then mix the 5 to 1 ratio of penacolite catalyst in with the resin to finish the glue solution.

Second, I learned that I need to elevate the mold to allow clearance for the clamps above the backboard. I should have found this out before actually trying to make a piece but its ok because the attempt last weekend wouldn't have been successful anyway.

Third and most importantly, I had the shape of the frame I was making wrong. I hesitate to admit this mistake but everyone makes them right? At least I caught this mistake now, especially before I actually make the piece. I had used the fuselage frame formula to draw the shape of this frame when I should have used the numbers given in the blueprints instead. I didn't catch that the numbers in the blueprints were different until I looked at them again this week. It makes sense that they are different because this frame is a diagonal frame and isn't against the fuselage walls in the same way as the other frames. I guess I was in a set way of thinking as I was chugging through drawing the frame jigs. I'll be sure to double check all of them now before I cut them out. So as it turns out, it was a darn good thing things didn't go well last weekend.

My main concern with the screw up was the strips of spruce I wasted in the process. It was such a big deal to get these in the first place that I was worried about getting more if I didn't have enough. It turns out Western Aircraft gives you enough strips to do either the standard canopy frame 4, or the nustrini canopy frame 4...which happen to be the same type of strips used in the frame 2 diagonal that I screwed up. Luckily again, this means I have extra of these strips so I won't have to worry about the ones I wasted. How lucky can I get.

Alright, round two attempt at gluing a successful laminated fuselage frame. Since I need to redraw the frame I messed up on last weekend, I'll make the next frame mold I cut out, the bottom of the nustrini frame #4. Tonight I did some set up work for the gluing. First thing that I needed were spacers to elevate the mold off the backboard. I took a 2x4 lying around and used the table saw to make some 6" long 0.5" high spacers.

I then re-covered the backboard with plastic wrap and nailed down the plastic covered spacers around the perimeter of the mold. As I screwed the mold down to the spacers, they began to split. I guess the 2x4 wood is prone to split when it's that thin and with the drywall screws I was using. Next time I'll make spacers out of spare 0.5" plywood which should not split. Then I did what I should have done last time, trial fit the strips in the mold while clamping. Here are a couple of shots of the trial fit process with the strips perfectly flat against the spacers. It's easy to see why I needed them. I should have done this before!

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