Wings

[Brock]

Finally ran out of chores to chase on the fuslage, for now, so had no choice but to switch gears from metal to wood.  Felt good to cut a few bits of wood.  Cut once measure thrice, or is that the other way around.

[Kamcoman77]

Looking good!

[Brock]

The spar-cap tapers were easier than I thought they would be.  Cut a wedge from a 2x4, taped it to the spar-web and ran it through the table saw.  First glue tomorrow.

[Brock]

Glued up the second front spar today.  Just like Isotopes, I had to add a bit (1/8th inch) to my filler block.

Tomorrow I am going to try out the scarfing sled which was setup, today, with a Hitachi router.  This Scarfing will be a first for me.  Hope to scarf all four spar webs in one go.  There is a lot of surface area in common between the spar-caps and spar-web.  I'm begining to think it might be better to glue it with TitebondIII instead of T-88.

[Kamcoman77]

I made a scarfing jig and tried a router as my 1st choice. Either the bit wasn't sharp enough or the router speed was too slow, but the thin plywood edge at the end was torn quite a bit. I added a steel strip at the end of the jig and switched to a belt sander. Worked great. If the router works for you, it will be a lot faster. I just wasn't happy with my test scarf using my router.

[Brock]

Using the Scarf Sled for the first time was not as difficult as I had feared.  After figuring out how it is supposed to work I made a few slight mods.  First was to put a board across the top and make some wedges to hold the plywood. I also screwed a hold down 1/4" peice to keep the end of the ply from lifting.  Finally used several 1/4 slivers to guide the router sled.  I'd remove 1/4 inch after each cut this way the router was better guided and not free to go all over the place.  After the first scarf the following 7 went smoothly.

The result seemed good enough, to me, to glue.  So I glued up (t-88) the two front spar-webs.  Look forward to seeing what I have tomorrow.

[Brock]

Glue day.  Like much of this build I've learned along each step.  I started by sanding the glue joints with 120 grit then layed the web on the bench and traced the glue locations onto the web.  I put a few stapples through the web into the bench.  Mixed up 55mm of T88 then eventually another 40mm and applied it to the web with a shortenend acid brush.  Took 25-30 minutes.  Good thing working time is 45 minutes.  Now that the assembly is safely weighted and becoming strong I took time to do more research on T88.  Something I didn't know to do before hand.  What I learned is the technique of applying glue to both surfaces.  I'm not sure if I would have had time to do that without a second pair of hands.  Still thinking about this.

[Kamcoman77]

Yes, the best practice with epoxy is an even, thin coat on both glue surfaces, then check quickly for any dry spots, and apply extra, if needed. That's why I had a buddy help me by spreading the epoxy on the web while I spread it on the spar. We got an extremely even bond that way with no chance of any dry spots. I don't think I could have done as nice a layup without help. If you got a nice, even squeeze out of epoxy, you are good to go! Congratulations on your progress.

[Brock]

Here is (a tip?) what I'm using to spread glue for the web-spars.  Seems to be a bit faster than dipping the acid brush into a container.  Just mix up 55ml of glue and pour it into a 60ml syring.  Then squize out a bead of the right amount and spread it with the brush.  Learning how large a bead seemed to be kind of intuitive for me.  I do lay it on quite thick since I'm only applying glue to one side.

[Brock]

Making good progress.  Today I got out the cookie cutter and lightened the spars a bit.  I put like spars back to back and drilled them both at the same time.  Used a 'backer board' to keep the holes clean.  stappled inside of each hole to be cut so that both holes would stay lined up and the cookies would come out together.

Weighing all the cookies make me wonder if the effort was worth it.  Slightly over a pound for all of them.

[Brock]

After cleaning up and putting away the cookie-cutter, next on the todo list was to run all four spars through the table saw.  Main spars got a 10 deg cut and the Rear spars got a plywood trim.  This was a step where I felt things could go really wrong.  But with care it was all mostly simple.

Folding ladders make good table saw 'rollers'.  With the help of ratchet straps they can be adjusted to any height.

Finally, I found a spot where the glue was missed.  Haven't decided yet if it needs to but cut out and replaced or if it is possible to glue it without removal.  What do you think?

[Kamcoman77]

On the no glue situation, it should be easy to get the edge of a putty knife or chisel under the middle of the vertical. The plywood should bow a little. Squirt epoxy underneath, let it soak for a couple of minutes, and remove the "pry bar". Wipe off the excess epoxy and dance around the build table three times.

[GTS225]

Weighing all the cookies make me wonder if the effort was worth it.  Slightly over a pound for all of them.

A pound off the wings spars is a pound on a required spring or cable clevis.

Roger