Legal Eagle XL in Pennsylvania

[Pilotarix]

...Be careful to place the strips in the jig oriented so that the 1/4" dimension is toward the "most correct" side. ...

Thanks for your input. I think I understand what you mean. I assume that this is one reason that some use cam clamps rather than a jig with fixed dimensions in all directions. With cam clamps, one can account for varying dimensions of the cap strips as long as the correct dimensions in critical areas are being accomplished.


Today I wasted most of the time hunting for plywood sheets for the table. Prices are still insane, and in the big box stores, they had no staff to handle their panel saw.  I don't have a circular saw, so I cannot really handle full panels very well. I had to go to my hardwood dealer not to waste more time, which did not improve the price range.
On a positive note, the replacement from Online Metals already arrived,  this time with no damage.

With the plywood cut to the correct width, I could almost finish the table. Then my "administration" reminded me that other things would require attention as well.
To finish the day, I put the Piper skeleton on the table that helps imagination, and it looks pretty good there. Unfortunately, it's only  1:16 ...
The stupid lawn then killed the rest of the day...

[Pilotarix]

Back from a short vacation, and as Jon Croke always says at the end of his videos, "everyone back to building."

I am trying to figure out what rivets sizes the designer suggested for the tail surfaces. In the description he mentions, stainless steel rivets but no size; at least, I cannot find the size. I read somewhere about 1/8" stainless steel rivets, but I cannot find this in the plans. I must be blind  . I appreciate it if somebody could give me a little hint on how to find this information.

[Chuck in Indiana]

I'm back from vacations, too. Oshkosh (no legal eagles) and the Wisconsin Moto Guzzi rally.
1/8" rivets.. I don't remember  how I know other than that is what is called out on the materials list. Like much stuff on the materials list, though, there won't be enough.

[Kamcoman77]

I used Marson stainless rivets with stainless mandrel. The SSB4-1S rivets worked for almost everything. I did use some SSB4-2S rivets in a few places.

[Pilotarix]

Hi,

Thank you for your input!

I'm back from vacations, too. Oshkosh (no legal eagles) and the Wisconsin Moto Guzzi rally.
1/8" rivets.. I don't remember  how I know other than that is what is called out on the materials list. Like much stuff on the materials list, though, there won't be enough.

Excellent choice. I have never been to Oshkosh, tried many times, but there was always something else, and the rest of the family is not so enthusiastic that they would spend family vacation time in Oshkosh. The Moto Guzzi Rallye sounds pretty interesting as well.

I used Marson stainless rivets with stainless mandrel. The SSB4-1S rivets worked for almost everything. I did use some SSB4-2S rivets in a few places.

I read about Marson rivets in other places. It sounds like 1/8" stainless steel rivets are the way to go despite the material mix - stainless/aluminum - which is usually not recommended (galvanic corrosion) but seems to be pretty common. Hence it can't be that bad.

I spend the day working on the wing rib jig. I monkeyed around with the CNC router to make some little cam clamps. That was working well, so I continued with some blocks of different sizes. I included screw holes, but I did not use screws since the blocks always slipped out of position as I tighten the screw, no matter how careful I was. A downside of the lamination, that stuff is pretty slick. I ended up using a thin double-sided tape and a pneumatic nailer.
As you can see, the jig is not completely done. I have to make smaller cam clamps, and I have not yet decided how to clamp down the gussets until the glue is dry.

[Kamcoman77]

Here is a neat video by Les Homan. He built 3 Legal Eagles.

[Pilotarix]

Here is a neat video by Les Homan. He built 3 Legal Eagles. ...

Thanks for this link!

I think I saw that video a while ago. I watched it again, and this time I paid more attention to the details.
He seems to be pretty quick making these ribs. It looks like he has developed a good system and some practice.
There are a couple of things I am not so sure I would do them the same. He is using Tidebond III exterior wood glue. Nothing wrong with that specific glue. I have used Gallons of that in all sorts of woodworking projects, great stuff. However, this glue is not really good at gap filling, and there are gaps if not every piece of cap strip was fitted precisely. Also, wood glue needs even and good clamping pressure. He may have that on one side but not with the clothespins on the other side.
The clothespins are good for epoxy joints because high clamping pressure is not so critical with Epoxy. Actually, too much clamping pressure is not good for Epoxy joints since you don't want to squeeze all the glue out of the glue joint.
Anyhow, I might be too picky here, and we already mentioned that we are not building a space glider or the like. But, at some point, my "behind" is going to hang on these wings. So being a little bit picky is probably warranted.

[Kamcoman77]

I used T-88 for its strength and gap filling properties. All my test joints broke wood, not the glue line. Used cut back clothes pins for pressure.

[Pilotarix]

I used T-88 for its strength and gap filling properties. All my test joints broke wood, not the glue line. Used cut back clothes pins for pressure.

The clothespins are a great idea, and their clamping pressure is likely sufficient for an epoxy glue joint. As already said above, you don't want to squeeze all the glue out of the joint. I will probably borrow the clothespins idea.

In the last two days, I made a little bit of progress with all the prep work.

I had not had a good idea how to cut all the gussets, and all the suggestions out there are great but still not what I was looking for. I had laser cutting in mind and made some DXF files for the gussets using the dimensions given in the Iron Design wing plans. Easy task, did not take too long.
Then I got the diode laser out. What can I tell you? It was an entire failure.  It could cut the thin plywood in one pass, but the result was not pretty. Not at all, and it took quite a while for a little part. In the end, I was not too impressed by the burned edges and decided not to use the laser for cutting. A  CO2 laser would have been way different... but I don't have one of those.
Anyhow, I used the laser to make patterns of the gussets on the plywood, which worked, at least in my mind, pretty well and fast.
After making all the gussets, I cut all the cap strips on the table saw—nothing exciting here. Some minor tweaks on the jig, and I can start making ribs.

Like many, I did a gluing test as well. I used T88, and the result was not really what I expected. The glue joint did not fail, but the gusset came of the cap strip quite easily. I was not really impressed by that. It looks like the glue did not really penetrate the wood. Just the top layer and there, the whole thing separated under stress.

Today I did another test with T88. This time with a little bit more glue and I paid very close attention to get the mixing correct.

I also made a test joint with WestSystem Epoxy. One without and one with adhesive filler. We will see tomorrow how that turned out.

[Kamcoman77]

Looking good! Those glue joints look very nice. I stacked 28 small sheets of 0.8mm ply locked with toothpicks and glued the Iron Design drawing on top. Cut several hundred gussets at one time with bandsaw.

[Pilotarix]

Looking good! Those glue joints look very nice. I stacked 28 small sheets of 0.8mm ply locked with toothpicks and glued the Iron Design drawing on top. Cut several hundred gussets at one time with bandsaw.

That is excellent; looks very efficient. I had the bandsaw in mind but wasn't sure if I could keep the pieces aligned while cutting. I should have tried.

I tweaked the jig a little bit. In the Iron Design wing plans, it is suggested to make the space for the rear spar slightly bigger, only 0.032", which should make it easier to fit the spar. Initially, I did not do that, but after I have seen a video where the issues fitting the rear spar were mentioned, I decided to increase the width of the rear spar spacer by the above 0.032".

I abandoned the idea of using clothespins after finding a pack of toggle clamps that I had bought a while ago for another project. I had thought about them earlier but also thought that they were way too big. But actually, looking at them, they weren't that big at all. So I gave it a try. They are mounted with only one screw. That is enough. It doesn't need much clamping pressure with epoxy, and I can rotate them out of the way.
With all of that done, I decided to go for a first glue-up.
Finally, I have chosen T88 over WestSystem, and the reason is mainly pot life. WestSystem is about 20 min, depending on temperature and the like. T88 pot life is about 40 min. Plenty of time to screw stuff up and correct it and still be able to finish a glue-up.

I go with little plastic cups and a one-way brush. If I use epoxy, I always keep the rest until the next day to see if the glue has been set appropriately. When problems arise with the glue joint, I know if it was the epoxy or not.
I used this little scale for mixing, which takes away the guesswork, and I can always make the same amount. This first time I mixed way too much glue, but now I have a pretty good idea of how much I need and can do better next time.

I hope I get this thing in one piece out of that jig tomorrow; we will see.

[Kamcoman77]

Toggle clamps look great and your woodwork is very nice. I would have used toggles if I had more on hand, but the clothespins worked fine for me. Most of my ribs took between 35 & 45 minutes to glue up (all parts). Never had a problem with T-88 open time. Even did some tests waiting an hour before gluing and the joints never failed at the glue line.

[Pilotarix]

Toggle clamps look great and your woodwork is very nice. I would have used toggles if I had more on hand, but the clothespins worked fine for me. Most of my ribs took between 35 & 45 minutes to glue up (all parts). ...

Thanks!

In all the discussion about different Epoxy glues, the long pot life and the viscosity really stick out positively with T88. WestSystem, as much as I like it, is pretty runny without thickening and unthickened better used for surface coverage than gluing.

I found an advantage of clothespins over toggle clamps. These toggle clamps, when closing them, pull the workpiece inwards and out of position. The whole thing is worsened due to the workpiece gliding on the glue, not really a problem, just something to be aware of so it can be corrected.

I need about 55 min for a glue-up. I wet out the entire surface of the gussets with epoxy. That may give a little extra strength to the gusset, and I don't need to worry about wood protection in these areas when it comes to varnishing later in the process.   

I still use too much glue, so I have some squeeze-out. I mix 12g for the glue-up and still have some left in the pot at the end. The squeeze-out is, unfortunately, in areas that I can't reach very well after clamping. This will cause some sanding later.

I keep the rib for about 12h in the jig. This will allow me to make 2 ribs a day, one in the early morning the other one late at night. One rib has about 73g.

I am about to order the rest of the wood at ACS. However, I still think about alternatives, like the Doug Fir I have in my garage. Just for the spar caps. Last night I read a lot of information on aircraft wood, usable species, availability, grading, and so on. It sounds like we have to look for alternatives to Sitka Spruce and ! Doug Fir soon. 

[Pilotarix]

Hi all,
I am about to start the vertical stabilizer and rudder.
The rudder fin plan calls for a 5" radius on the upper bend but I cannot find the specification for the lower bend radius. I compared this to the elevator, the radius looks pretty similar, and there, the radius is given in the plans, 6". So I choose a 6" radius. Now I have seen that some have used a 3" radius in that location. Is this information in the plans and I just miss this? Is the radius critical here?

Thanks
Christoph

[Kamcoman77]

As I remember, I used the same 6" radius block to bend both angles, just did not bend the bottom angle as far. My finished rudder was pretty close to the plans but a little smaller area. Attached are photos of my rudder and two others showing those builders decided to use their own shape. Here is your chance to be creative!