Legal Eagle XL in Pennsylvania

[Chuck in Indiana]

I'm back from another trip and a fly in.. yeah, I've been slackin.' 
I made all the plywood parts with a toy router that I bought just for this project. Made router templates on the cnc, and whizzed them right out.
I also used it on the scarf joint.

test piece to check scarfs and the hole thingy..(technical term)


Nice work, attaboy! Keep it up..

[Kamcoman77]

Looking good! What kind of plywood is that?

[Pilotarix]

Somehow I am missing the reply from Kamcomann, I saw it earlier, and now it seems to be gone, mysterious...

Certainly both great solutions, thanks for showing.
For boat building, I used a hand plane to make scarf joints. I think I am going to step up and use a machine this time. I have both machines, a small router, and a hand-held band sander, not sure what route I am going.

I will use Birch plywood from ACS even though the shipping cost is really a pain in the behind. The order is out.. sure, I am getting an email that this will take months. Not the plywood but the Sitka Spruce.

Today I made the second left-wing compression rib, two more to go and 14 in total.

Then I  used the bending dohickey for the first time today, and it worked well. At least the tubing did not kink. There was a learning curve, but in the end, it went fine. Unfortunately, my workspace is limited, and I did not want to cut the tube before making the first bent in case something would go wrong. So I had to relocate my pattern and the bending blocks after the first bent—a little cumbersome. It was good that I had the pattern on paper.       

[Kamcoman77]

Looks very nice. Wait until you bend the aluminum. There is even more spring back. On a couple of my bends I had to move my block inward twice.

[Pilotarix]

... There is even more spring back...

No doubt, lots of spring back. I had to move the blocks as well, more than twice.

I have not been very productive, at least not in the shop. This is my "work weekend," so I expected not to get a lot done. 

I transitioned more of the plywood parts into the CAD system. As soon as my plywood shows up, the CNC can start cutting pieces.

While bending the trailing edge, I realized the significant difference in diameter; 3/8 tubing is connected to 3/4. To keep the center of the tubes on the same level, I 3D printed some little blocks. They keep the 3/4 tubing a little more than 1/6 about the surface, and both tubes center on the same height.

Also, the material to make the hinges arrived today. The 7/8" 0.058 tubing fits perfectly over the 3/4". So far, so good.  What is not so perfect are my welding skills. So that is going to be interesting. I welded many test pieces in the last couple of weeks, it has gotten better, but the results are still light years away from producing something usable. 

[Kamcoman77]

Beautiful tubing spacers. I just used wooden blocks. A1 does not go anywhere! Don't bother making it.

[Chuck in Indiana]

Since I already had them made..I sawed them off and used them for a filler.

[Pilotarix]

Beautiful tubing spacers. I just used wooden blocks. ...

Thanks, they look cool, but wood might be much better, not sure if the 3D printed spacers will stand up to the task. PTE printed stuff is not the strongest. I will see how it goes.

I have to get serious about the rivets I want to use for the tail. It will be either the stainless steel ones called in the plans and recommended here or Cherry Max, from which I have some, but probably not enough.
I made some tests with the Cherry Max CR3213, grip length 01 1/32 (.032) 1/16 (.062), which has a minimum shear strength of 505 lbs.

I can pull them either with a hand tool or my pneumatic rivet puller. Either way, they seem to sit OK.

In the 3/8 tubing, the length becomes an issue. For the test, I drilled all the way through the tube. If there is no hole on the tubing's opposite wall, the rivet might not sit flush with the aluminum sheet when pulling.
Also, the rivets cannot sit as opposed to each other they need to be spaced differently on the front and back, at least in the 3/8 tubing.
In the pictures, the rivets are not exactly on center that needs to be improved as well.

Side note, I used the Olfa knife to cut the aluminum sheet and it worked great. Nice clean cut.

[Kamcoman77]

Marson SSB4-1S rivets fit a 3/8" tube from opposite sides perfectly. I got mine from Bay Supply using eBay.

[Pilotarix]

Convinced, I will use stainless steel rivets as well.    The Cherry Max design with the mandrel sticking out doesn't fit the same way.

I did the first aluminum rib for the rudder fin last night. Cutting the material with the Olfa knife was really easy. I had some thin adhesive-backed neoprene rubber lying around from another project. I used that to cover the back of a metal ruler. That prevents the metal ruler from sliding around on the aluminum while I make the cut.
I bought the cheapest bending brake from Harbour Freight, not a delight, but gets the job done.

[Kamcoman77]

Nice looking rib. A suggestion: if you cut off the small triangular piece overlapping the LE or TE, your gussets will lay more smoothly against the tubing.

[Pilotarix]

Funny, I thought about it ... you are right. The corner should be cut off. Thanks.

As I said, the Harbour Freight bending brake gets the job done, likely because the material is so thin. It's really cumbersome to work with the F-clamps, but that is how it is. The internet is full of videos on how to pimp your cheap Chinese bending brake. This is what I really hate on that stuff; if you buy it, you always get a new hobby for free  . Anyhow, for the handful of ribs, it's gonna be OK. If I had to make 100, I would look for something else.

[Kamcoman77]

Looks like that HF brake is working fine. The bends in your rib look straight and crisp. Very nice work!

[DA Miller]

Chris, a suggestion: if you haven't already done it, you might put a small radius in the root of your rib bends.  Al does not like sharp 90* bends.  The thicker the Al the more important; it tends to crack.

[Pilotarix]

Chris, a suggestion: if you haven't already done it, you might put a small radius in the root of your rib bends.  Al does not like sharp 90* bends.  The thicker the Al the more important; it tends to crack.

Thanks, will try with the next bends and see how that works.

Looks like that HF brake is working fine. The bends in your rib look straight and crisp. Very nice work!

Thanks, the brake is working better than expected, just the handling is somewhat cumbersome.


Things slow down a little bit. I did not get the plywood so far, so I can't make the parts I need to make rib #7 and so on. I think I start sanding the ones I have and change my jig a little bit so I can make those ribs with a K-block and the like.

The stainless steel rivets are ordered but have not arrived yet. Anyhow, I still need to clean up the aluminum ribs and make the gussets, enough to do until the rivets show up.

And there are still the hinges waiting to be made. I need to have enough time to approach this without pressure, and I have to make some test pieces first and see how it goes.

Today I made only one aluminum rib for the rudder fin, and they are all done now. Actually, it was much easier than I had thought. Cutting the thin aluminum with the Olfa knife is really easy and gives good and clean results. A big help is the rubber backing of the ruler. Before that, the ruler slipped around on the aluminum, and I had to push on it really hard to avoid that. With the rubber backing, it sat rock stable and did not move at all, so I could concentrate on guiding the knife.

Unfortunately, there will be no time for building during the holiday weekend.