February 24, 2008

Time to put ribs in this tank - 1.5 hrs.

With the stiffeners, fuel cap flange, and drain valve all in place, it's time to begin putting ribs in this tank. Tonight, in just an hour-and-a-half, I was able to fay-seal 3 ribs in place. I really like this fay-sealing method the more I use it, so I will continue to do so.

I did the three inner ribs tonight, as you see above. My strategy is to do the inner ribs first. If necessary for access when riveting or sealing, I can remove the outer ribs and be able to reach in there. The end ribs will go on last. You can avoid making a big mess by smearing the sealant on the rib flange instead of inside the tank, then very carefully inserting it into the tank, and cleco it in place. It's as simple as that. The other ribs are clecoed in place, too, just to hold the tank's shape and keep things rigid. But there's a cleco in every hole of these 3 ribs, as you can see above. I'll rivet these ribs in place tomorrow or the next day, depending on how much the sealant has set up by then. In this weather, it stays soft and pliable enough to move around for as much as 3 or 4 days. It's about a week before it's fully cured. I'm actually very glad to be doing this in the middle of winter. There's no time pressure. The schedule would be much different in summer!

By the way, I might mention a word or two about the sealant, or Pro-Seal, and how I'm using it. Van's manual suggests mixing up a portion the size of 4 or 5 golfballs of this stuff. But that's way too much at one time, in my experience. A lot of it would be unused and go to waste if I mixed up that much at once. You only want as much as you can reasonably apply in one work session. I'm using a small digital scale to weigh it, so I can get the exact 10:1 ratio of sealant to catalyst. I use small disposable paper cups, and weigh out about 30 grams of sealant at a time. That means it only takes 3 grams of the black catalyst for the proper ratio. I literally use a toothpick to scoop small amounts of it out of the jar and put inside the cup beside the sealant blob before stirring it up. There is no particular preference for grams vs. ounces in my mind, but with small amounts like this it's easier than trying to figure and weigh out fractions of an ounce for the mix ratio. If I put a blob in the cup and it's, say, 33 grams, for instance, no problem. You don't have to be that exact. Then you just add 3.3 grams of black catalyst for the correct mix. Add 2.7 grams of catalyst for a 27 gram blob of sealant. See how easy that is? This little scale measures down to 10ths of a gram. One batch like that is usually enough for me for one work session. However, if you have some left over, you can just put the cup in the freezer and use it again the next day. I've done this a lot. After it thaws out, you're ready to go in minutes. This is real handy if you only need a tiny amount for something.

My little digital scale.

The scale has a TARE button, to zero it out after you put the empty cup on the scale. It's so easy to use this way.

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