I spent some time cutting geodetic braces. I stacked five of the thin capstrips, laid out the parts along them, and cut them with the bandsaw. I now have enough parts to make half a dozen more ribs. It’s slow going with the geodetic capstrip, because each one has to make three passes through the spindle sander to shave them down to 3/32″ Holy crap that’s tedious. I may try using the table saw when the thin strip rip jig arrives. Even if I can get them close enough to just make a single pass on the sander it would be a huge improvement.
I tried a different technique for applying the glue. First I dry-fit all of the parts to make sure I didn’t end up with a brace with glue all over it that needed to be trimmed. I marked the top and bottom capstrips with a pencil to indicate where the groove needs to be glued. Then I pulled them out of the jig and used a trimmed-down popsicle stick to apply epoxy to the grooves. Back into the jig, with the front and rearmost vertical pieces in place since those are impossible to install with the capstrips in the jig. Then I proceeded as usual, installing all the other parts with epoxy. It worked like a charm, and resulted in no glue running down where I didn’t want it. We’ll see how this rib looks when I pull it out of the jig tomorrow… and we’ll see how closely it matches the first one. In theory they should be identical, but I’ve never done this before, so…
This morning I pulled the first rib out of the jig to check it out. I was a little apprehensive about it, to be honest. I had tried to use a little digital scale to weigh out the epoxy, and that didn’t work well. The scale didn’t see tiny increases in weight as “activity” and would power itself off every few seconds. I ended up “eyeballing” the mix by volume, and hoped I got it right. With a little less than 15cc of glue I was hoping it was right, and last night it was still feeling a little “tacky”. Well, this morning that epoxy is perfect, nice and hard, glossy surface and zero tack. My test piece with a couple of scraps of geodetic brace glued with no clamping broke apart in pieces, with no failure at the glue joint. The wood failed and the glue didn’t. Success all around.
The only deficiency I can see is, there’s maybe a little more glue than needed. Glue had run down under several of the joint areas and I have some cleanup to do on the “bottom” side of the rib, the side that was against the jig surface. I’ll need to figure out how to get the right amount of glue in there when I pre-glue the groove. Other than that, it looks really good and I’m thrilled with it. It looks like about 10cc is what is needed to glue up a complete rib. That means when I get the second jig built, I can mix up 20cc and glue two ribs at a time. The more glue gets mixed at one time, the easier it is to get the mix ratio perfect so that will be good.
And, I’ll have to put this rib somewhere in the middle of a wing where it can’t be seen by the Oshkosh judges. That way it won’t screw up my chance at that gold Lindy. 🙂