Rib #2 matches rib #1 to within plus or minus a millimeter or two everywhere. I spent some time with an X-Acto knife and sanding block cleaning the excess epoxy off of the first rib, so it’s looking pretty good now. Tonight I put #3 in the jig and glued it.
I was planning to make the second jig tonight also, but that’s going to just have to wait a little while. The garage is getting too cluttered to work in. I’ve got numerous tasks partially completed, and it’s a real mess.
I need to finish grooving the capstrips, first off, so I can use the table saw for other things. (done!)
- I need to get the rest of the geodetic stock shaved down to final size. I got my strip cutting jig from Rockler today, so we’ll see if the table saw can be used to help with that or not.
I need to cut more wood blocks for the jig. With the spindle sander, I can make sure they are perfectly square. (done!)
- There is some cleanup to be done, including two workbenches that are piled high with so much crap that I’m working with a rib building jig hanging over the sides on one end of the bench. It’s an eight foot long bench and I’m using less than a foot of it. Ridiculous.
- I will need a place to store these ribs so they don’t get damaged. And I definitely have to find a better solution for the geodetic braces. The paper cups I have been using were a terrible idea. They take up enough room that they’re a pain in the ass to use, and they tip over, fall off the bench and spill parts everywhere at the slightest bump or touch.
- I have the table saw and spindle sander sitting halfway out in the middle of the floor, need to get a permanent location figured out.
That will at least get me to where I need to be to keep building ribs. At some point I’m going to need another eight feet of workbench, but that can wait until I have the ribs and tail feathers built. Pretty sure I can do all that on the 3 x 8 that I have now.
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. 🙂
After a couple hours of cutting and sanding geodetic pieces, I finally mixed up a little T-88 epoxy and glued up the first rib. Kind of a milestone — the first full size wooden rib I’ve ever built. Can’t wait for tomorrow when the glue is hard enough to pop it out of the jig. Then we’ll see whether this one gets used on the airplane, or used for destructive testing.
Cutting those geodetic pieces is a lot of tedium. Even more so since I didn’t aend the strips before cutting, so I then had to sand each piece individually. next time I’ll clean up the capstrip prior to cutting. I was cutting two pieces at a time, with the capstrip stock taped together. I may go for 4 or 6 pieces at a time as I get better at it. And, I need a better solution for holding the pieces. I knocked three of those cups off the bench at various times while assembling it. Things will be a lot easier if and when Pete’s R/C Cub gets off my workbench.