RVG8tor

RVG8tor

Well Known Member
I am just starting so forgive me if this seems trivial. I have read a little of on this forum about fluting (not much there) and also Van's instructions. I understand that I want all of the holes to line up on the rib. But could someone explain or refer me to a source on just how to do this. I don't understand where to flute given a an end being too high or too low. I get the ends to line up but then the middle holes are too low, I relax the middle and then ends don't line up. My VS rib is lined up on one side then the other has a high end, I get that end down and everything else goes out of whack.

So how do you start, fresh part laying on the table (flange down I assume), you look at if and then what? Thanks for any help.

Signed "Frustrated"
 
Hi, here are a few ideas that may help:

1. You want the rib to be roughly flat when the web is down on a flat table. Great precision is not necessary.

2. Many, but not all, of the ribs will magically lie flat and line up if you put a moderate flute midway between each pair of prepunched rivet holes, on all of the skin-facing flanges. Start slow and increase the size of the flutes if necessary. You will develop a feel for it over time.

3. If just one area of a rib seems off, start in that area. This is unusual, though.

4. If you're still having trouble, it might help to hold up a ruler and compare that to the line of holes. Areas that are curved compared to the ruler need flutes.

Here's a decent photo of some fluted ribs from Dan's site: http://www.rvproject.com/20020513.html
 
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Mike: This is how I proceeded. I am a first time builder. I cleaned up the pieces with scotchbrite pads and or my die grinder. The edges have sharp points and edges from the cutting process (a shear). When nice and smooth by finger touch. I took a small "square" and carefully adjusted the edge, bending it to 90 degrees with the web. After that I took the fluting tool and crimped between the predrilled holes on the edges until the rib web would lay flat on the table. After I assembled with cleco's...I double checked to make sure that the edges were resting evenly on all the edge surface with the skin. Hope this hasn't confused the issue. It may be smart to locate someone in your area or a local Tech. counselor to lend a hand for ten minutes to demonstrate this.
 
Web down?

Ok so that I understand; you seem to be saying that I want to rib to lay flat with the web against the table instead of the flanges. I have been trying to get the flanges to lay flat on the table and along with that have all of the holes in the rib line up when a flexible ruler is lined up on the holes. Thanks again.
 
Practice, Practice, Practice.......

I still have 16 ribs for my bi-plane that need fluting. Come on down and practice. I promise when you are done with mine, you will have no trouble with yours. Mine are "full" ribs from leading edge to trailing edge, so they are a bit more challenging.
 
Greg,

Your narrative on your technique was just what I was looking for on this subject. The just go for it technique causes too much frustration. Having an idea as to which place to flute to bring and edge up or down was just what I was looking for. I just don't know why I did not find the thread when I did a search on fluting. Thanks for the info and I agree with one of the posters to your technique, it needs to be added to van's instructions.

Cheers
 
Thanks for the compliment.

One of the posters mentioned using the 'string theory'. This is where you use string instead of the flexible ruler. Just 'thread' the last hole on one end and tie a couple of knots on it to keep it from passing back out. Then cut a foot more than you need and pass that through the other end hole, but don't tie any knots there. When you pull the string tight you can see the hole orientation a bit better and you can leave the string 'attached', just pull the long end tight after each round of fluting. I have been using this method and it is a bit quicker than the flexible straightedge.
 
Fluting with a string

I didn't know if I had dreamed it all by myself or if I had read it in these forums, so a quick "Search" found this thread. As Greg described in the previous post and someone else ("Briand," no name provided) said some time ago, a string can be used to help flute those wing ribs.

I have been busily fluting my wing ribs lately using as an aid a very small strong string about 36 inches long with a washer tied on one end (doesn't have to be a washer, it was just lying around). By threading the string through the two holes farthest apart and stretching it tight over the outer surface, and with some practice, I can quickly see where each flute can be formed.

A little fluting goes a long way. By plunking the string occasionally as with a chalk line, the method seems to be easier for me than laying the rib flat on the table. Don't try to flute it with just a few flutes. Several small flutes seem to provide better results than do fewer deep flutes.

Perfection is not necessary; I am of the belief that the string passing over the holes is a good indicator of how straight the row of holes is. Profound, huh? Anyway, as someone said, the clecoes, when installed later, will pull little misalignments into shape.

No photos, so I hope the above is sufficient to help someone else.

Maybe I should have titled this the "Fluting Thread Thread."
 
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The only thing I can add is that I held my fluting pliers well forward (choked up) and used a bit more than handshake force. I tried to go between every hole when I had a smooth curve to take out, but passed over areas that looked good.

I have a pair of pliers with 4" wide jaws (HF welding pliers I think) that I occasionally used to flatten the flutes a bit when I got carried away.

The first couple I didn't know any better and gave a good squeeze from the ends of the handles thinking that's why the pliers were so long. :eek:
 
I enjoyed the fluting! I would do it while watching TV using a flexible ruler, like mentioned above, to line the holes up. It was like a game to me.
 
EAA video

Look at the EAA instruction video on how to flute a rib in the sheet metal section. They are using a rib that is handmade and does not have the pre-punched holes but you will get the idea. You don't have to get a rib perfect (it's not a space craft), once close it can easily be aligned when the clecos are inserted. You also don't have to flute between every hole. In flatter areas it may only take a small flute between every second or third hole, only in the curviest top front of a rib may you need to flute between each hole. You only need to do as much as necessary to get the rib to lay (web side down) reasonably flat on a table.

http://www.eaa.org/video/homebuilders.html

I think it is important to point out that it is not uncommon for a new builder, in an abundance of caution, to be too precise or fixated on exactness that is often overkill. This can lead to undue frustration, slow progress and at worst abandoned projects. I strongly suggest finding a building mentor in your area that has build an RV or other aluminum airplanes that can share his/her experience. Just having someone who can say you are doing a good job and not to sweat the small stuff will boost your confidence and accelerate your progress.

Good luck
 
Frank Smidler said:
.....I think it is important to point out that it is not uncommon for a new builder, in an abundance of caution, to be too precise or fixated on exactness that is often overkill.......
Click to expand...
Frank,

Your comments are 100% absolutely dead-on true. Some builders seem to obsess about fluting as much as others do about deburring. As this demonstration illustrates, if it takes longer than 60 seconds to flute one rib, you are wasting time:

http://www.vansairforce.com/community/showthread.php?t=28076
 
Fluting Thread Thread

The String method is definitely not "fixating on exactness" the way I use it. I haven't timed my ribs, but I would guess about a minute is about right. The EAA video referenced above, while showing several valuable tips, uses a Sonex rib which doesn't have holes pre-punched so you couldn't use a string on Sonex ribs.

The whole point of using a string is that you can see if the holes are in alignment or close to it. I'm not saying one method is better than the other, but I like using a string since the rib holes (not the rib edge) must align with the holes in the skin. As long as the string passes over the hole, it's close enough for me. Afterward I lay the rib on the table, and it lays flat. So the method must work!

Don

P.S. I will admit that for the more highly curved top of the leading edge ribs, the string method is not as easy, so am fluting those parts by laying them on the table as Rick and others have described.
 
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EAA video hint for fluting ribs

Having just completed my first "concert" of flutes on my RV 8 HS ribs, I wanted to add that I too used that video to help understand the process, and I too became unsure about the number of flutes that should be applied (between every hole, or only some of them, etc.)

So I really appreciate the comment about not needing to flute EVERY gap between flange holes, because I did not find that to be necesssary on every rib. For example, my end ribs on the HS only required 2 flutes each on the top and the bottom , near the center, to get everything lined up pretty good.

While the rib used in the video was not prepunched, I believe that he also draws a rough center line with a sharpie down the center of the rib prior to fluting (another technique that I practiced performing which worked out fairly well). Maybe this was on one of the other videos in the series all about ribs, but I think it was the same one. If so, there is a reference line of sorts to work with even though the rib is not prepunched or drilled. I can't wait to apply the string or flex ruler method on my VS and tail feather ribs to see if I too can reduce the amount of time it takes to do this. Thanks all for the great info!
 
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