Eagler's Nest
General Category => Builders logs => Brock's bits - LEXLV3 => Topic started by: Brock on January 21, 2026, 07:55:38 PM
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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.
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Looking good!
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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?
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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.
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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
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Today I cut and glued 1/8" ply on the root of the Main spars then took to working on cutting Strut-Block ply for both the Main and Rear spars. Rear spars plywood to be saved where I can later find them as they go on after the ribs. To locate the filler blocks I marked a peice of tape at 77" on the bench then marked two lines one at 5/8" and the other at 7/8" (5/8 + 1/4 for the rear spar). Then using a ruler I could extend a centerline down the filler block to intersect the appropriate location. See pic.
Q: for the plywood on the main-spar strut filler block, there is a choice to be make (see pic). The plywood will overlap the location where a rib is located, thus either the rib will have to be trimmed 1/8 to allow for the ply else the ply will have to be cut to just meet up to the side of the rib. What have folks prefered? Seems not cutting the plywood gives more strenth to the spar.
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Was not asking about rib 3, that ply will but against that. Instead I was asking about rib #8 (I think it is). Should the ply butt against the rib or do I want to trim the rib by 1/8th" and glue on top of the ply?
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I cut the plywood to fit against rib #8. However, it would be easy to notch the rib if you want the longer ply. I doubt it makes much difference.
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I measured twice but failed to check the math. Came up short. Will have to sleep on it to decide if I'll remake the parts or punt with some other solution/fix for these short ply pieces.
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I made mine too short also. Since the ply is epoxied to the spar and the fitting bolts over it, I decided to add a short piece butted against the larger one. Looks fine after epoxying the fitting over the ply.
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I ended up remaking the eight U-plies. Really went quite fast (20 min?) since I already had it figured out. Now I hope that the material I used isn't missed elsewhere down the road (er runway).
Let the fun begin! Today I took the plung and started adding/removing/adding-again ribs to the rear spar. What fun it is to see things come together. After taking this pic I did find one gusset on rib #3 still needing trimming. Ok back off they will come. Get it right before the glueing begins.
I came up with a sort of code to mark the rear spar with. First I numbered the location of each rib, the marked 'S' for the locations that will be modified for a compression-Strut, then marked 'K' for those that get a K-block. Marked 'D' for..... Hmmm I forgot what that stands for. Anyway a rib like 7 had '7SK' penciled on the spar next to it's location. That's rib 7, gets compression strut mod, and has a K block. There may be easier ways to keep track but this seemed to help me.
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Rib #7 also needs the 1/4" ply doubler to support the inner aileron hinge block. I made mine longer than the plans show.
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Ah, yes. 'D' for doubler. I was thinking ribs could get glued w/o that and a lot of other items. I do need to purchase some 1/4" plywood but am unsure what to get and where to get it. Any advice? I know there is a nice specialty wood store in Portland OR that I visited about 20 years ago but I've not idea what it's called or where it was. Will have to try and find it.
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Many builders have substituted marine grade ply for aircraft grade ply. Should be several boat supply stores in Portland. I believe you may also need some 1/16" and 0.8mm ply for the outer two ribs (aileron hinge block reinforcements).
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Thanks for the pics, they are helpful. One more question. Should I remove all the gussets on one side, aft of the rear spar, on rib 7? I would assume this needs to be done for the doubler (root side right?)
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Yes, I also put some ply on the tip side of #7. It covers the K-block
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Was delighted today to find that the table saw, carefully used, does a nice job on removing gussets. This will save a lot of time with the dremel.
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I set up a router table to do the same thing. Seconds to accomplish and very neat and clean results.
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You had a question about diagonals being epoxied to the lower rib capstrips where they cross. If you fit the diagonals to the side faces of your spars, the diagonals will touch the ribs. Hopefully, you are not referring to Leonard's Wing Video for any of your XL construction. The video does not apply to the XL wing.
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For the build log. Rear spar diagonal glue-in details. The 1/8" block is not yet glued, so if it looks a bit dry... A large gusset will go over the top of it all.
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Cut the root diagonal brackets today. Will hold them in the vice when welding to be sure to get the 46 deg that I calculated.
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Looks nice! Keep on truckin'
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Looks nice! ....
Wowa! Hold that complement!
I was just looking over the Irondesign videos and the diagonals jumped out screaming at me. "Backwards!"
Now I remember double checking everything thrice before I started glueing those in but I'm now realizing they are slanted the wrong direction. Someone take a look and confirm this. Could be I'm tired and just don't see it.
The pic below shows my wing with the root to the left. Hat covers the end to keep me from walking into it. All along I was thinking the first diagonal bolts up to the front spar but now I see it's the aft spar?!
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Whoops! Better call Leonard and ask if this is critical. You could probably put in a couple of new diagonals running the other direction that would create an X. I was thinking about doing that.
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Whoops! Better call Leonard and ask if this is critical....
Kamco, thanks for the suggestion. I just spoke with Leonard, he sounded good, how old is he?
Anyway, Leonard said to leave my diagonals alone and fly it (I need to build it first). That it's not a high powered machine (understatement). It's still a diagonal as far as he is concerned (though in tension rather than compression). Now, I'll have to decide to make the second wing correctly or make them both the same. Didn't I already mention how I like semetry?
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Leonard turned 101 a few months ago! He is a truly amazing man. I would build my 2nd wing with the same diagonal orientation as the 1st. I like symmetry, too. I had a feeling that Leonard would say it's OK as you built it.
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Today I cut the wing trailing-edges and glued on the first of the gussets to support the tailing edge. The cutting of the 1" x 3/8" x ~10' peice has been the subject to my latest day-dreams (er night-mares), how was I going to do it. Although I liked the 2X4 & carpet tape solution, I decided to just cut the wood without the 2X4. The magic bullet was this hedgehog-featherboard that I picked up to try. It worked like a charm, I recommend it. Here are a few pics.
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Realized today that I had forgotten to place gussets on the bottom of the diagonals. Once I got to looking at the spot, it became clear that overlaping the front spar was not going to work as it would interfere with with the nose ply. Pictured is what I'm thinking of doing, can't overlap the spar-cap. What have others done?
The otherside of the diagonal is gusseted properly with the gusset overlaping the spar cap.
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I did not put gussets on the bottom side of the front diagonal joint, only on the top side.
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I don't remember.. ::) I"m old.. sue me.
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I think I added 'filler' so my front skin could glue to something, but I'd have to go back to my videos to know for sure... :P
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It's beeh awhile since I've posted but be assured progress, albeit slow, is progressing. I was struggling with how the ailerons go together then it finally clicked. What was hard to understand was to differentiating between what is costmetic (ie. the plywood on the ailreon ribside that is exposed when the alierons are not mounted) vs what is structural (ie, the 1/4" ply that holds the hinge blocks). Once this was understood things started falling in place.
Yesterday I glued in the brass hinge tubes. With this done, the aileron spar can next be built in place then it will be time to start the second wing. Should take only a fraction of the time of the first wing.
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"Should take only a fraction of the time of the first wing." You're right! In addition to the learning curve you have all the tools, knowledge, jigs, etc., ready to go. My first wing took 6 months. My 4th one took 28 days.
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... In addition to the learning curve you have all the tools, knowledge, jigs, etc., ready to go....
Well, I also have the spars built and tappered, trailing edge wedged-cut, etc.
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A picture is worth a 1000 words, or was that 1000 glue joints?
Having hung the first wing on the wall can mean one of two things. Either I've hung it up or I'm about to start the second wing. Hopefully it's the second.
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Looks good! Now for the interesting part, getting the nose ribs and ply on.