Wing Rib Fluting — Part 2

I found an hour or so to finish up the main wing rib fluting.  Like the last session, I used the table top method on our granite countertop and knocked out the remaining 14-something main wing ribs.  They stack much nicer now that they are all formed straight and with proper flanges.

I was going to start working on the leading edge ribs, but decided to hold off on those guys, because I think I will modify my flange straightener tool to work with these curved edges so I can more easily get the flanges to 90 degrees.  Then I can flute them all.  No photos from tonights work, as it is pretty much the same as the last session.

Hours Worked:1.25

Wing Rib Fluting — Part 1

About a week ago, I decided to bring my wing ribs upstairs and do the fluting up here, since that doesn’t produce any filings or shavings.  HOWEVER….I have had a lot going on family wise that I haven’t been able to spend much time on them.  I’ll also admit that over the last few days I have actually been fiddling with these things to the point of frustration.  I tried a few times to sit down and get the straight using the wood dining room table as my “flat surface”, and always end up frustrated because no matter what I tried, they never would come out straight.

You see, we have to flute  the flanges on the ribs because during the forming process they will get bowed a bit.  Fluting “shrinks” the metal down along the flange, pulling it back straight.  See how they are from the factory:

It seems like a simple process, and it actually is…..if your reference surface is truly flat.  😐  Turns out, our dining room table is not exactly flat, and I was using this bowed/curved surface as my guide and my ribs never came out right.  Once I realized this, thanks to my wife Tammy, I decided to use our granite counter tops, since I knew they’d be nice and flat.  After switching over to the stone counters, I ended up using the “table top” method of rib fluting.  This video shows how to do this method:

The results speak for themselves.  After I did the table top method, with the flanges sticking up I flipped the rib over with the flanges down towards the counter top to double check.  Then I used a metal ruler to measure that the rivet holes were all in alignment.  Some ribs (like the one below) only needed a couple of flutes, while others needed many more.

I ended up getting the process down pat, and was able to knock out 14 ribs using the granite counter to and “table top” fluting method.  I did have to go back and re-do the ribs that I did on the dining room table, since they were not straight.  I’ve got a lot more to go, but I think this method will help me knock them out quickly. Here’s all the photos from tonight’s work:

Google Photos Link:

Hours Worked: 2.75

Rib Flange Straightening — Part 1

Fighting off some sort of cold/sinus infection, I didn’t feel like putting in a whole bunch of work tonight, and I am still studying up for an Ansible exam but I did manage to knock out straightening the flanges on all of the wing ribs. All the ribs are pre-formed by Vans, but due to the punch and forming process, the flanges are not at a perfect 90 degrees to the the rib, so we need to bend them to a perfect 90.  The old way is to use a pair of hand seamers and do it all manually, checking with a square to get your bends perfect, but theres a better way.

A few months ago, while I was waiting on my wing kit to ship, I built a very neat little tool to help with this process.  I had seen several other builders make something similar, and they all raved about it, so I built one for myself.

It’s a pretty simple little tool. It’s made from a 2×4, a 1.5 x 1.5 piece of oak and some metal.  The anvil portion of the 2×4 (clamped down to my work bench) is angled at about 11 degrees, while the press handle is made from the 1.5×1.5 oak.  The 11 degree angle bends the flanges to slightly beyond 90 degrees, because the aluminum will flex back about 10 or so degrees, which leaves the flange at a perfect 90!  You can see how the rib sits in the tool here:

The 2×4 on the left serves as the “anvil” that the flange is formed against, and you can just make out the 11 degree angle on the face of the 2×4 (its tilting toward your right).  Also, notice how the handle portion (the oak 1.5x1x5 handle) also has a angle cut on the bottom.  This is a 22.5 degree cut I made on my mitre saw so that all the bumps and ridges in the rib would not get damaged.  They fit very nicely under this angled portion as you can see in that photo above.  Here is what it looks like without a rib in it:

To do the work, I just put the rib, flange facing upwards in the tool and apply pressure on the handle to bend the rib.  The result is a perfect 90 degree bend on the flanges! I can process an entire rib in about 20 seconds on this tool.  I’ll update this post with a video describing how to make the tool, and how to use it.  I think it cost me about $15 to make.  All in all, I was able to knock out all of the inner ribs for both wings in a little over an hour!

Google Photos Link:

Hours Worked:1.25

Wing Rib Deburring — Part 5 and DONE!

I wrapped up all the wing rib deburring tonight.  All that was left were the ribs for the fuel tanks, but like all the other leading edge ribs, they have all those little tiny flanges, and each one needs to be deburred.

I spent a little over an hour knocking the rest of these things out and then decided to do a little work on my flange straightening tool.  I had picked up a “edge rounder” routing bit so I could smooth the handle down a bit a few days ago, so I decided to move on to that for the rest of the evening.  I am not going to count those hours in the build log however, since I was pretty much just polishing up on the tool I made to help me get the rib flanges all at a 90 degree angle.  I’ll do that tomorrow and give details on it.

That (thankfully) wraps up all of the edge deburring for all of these ribs.  It took a lot of time, and wasn’t very fun but it had to be done.  I am just glad its over, so I can move on to some other task for a change! Here’s the stack of ribs I got done tonight.  16 total (I think that was the count):

Google Photos Link:

Hours Worked:1.25

Wing Rib Deburring Part 4

One Hour…thats all I managed to work on the airplane tonight.  I’ve got a lot going on with work and family right now, so I don’t have as much spare time to get down to the airplane factory and build the RV-7.  Spending a lot of time learning up on Ansible and Satellite 6 as well as IdM (Three Red Hat products I deliver for our customers), and with Dad in the hospital recovering from surgery, I don’t find myself with any time left in the days.  But, any step forward is a good step, no matter how small.

Tonight, I simply finished up deburring 14 leading edge ribs, which includes all the little tabs and slots on the flanges.  Man, these things are a pain in the ass to do. It’s not so much difficult work, as it is tedious and boring and repetitive. It’s got to be done though!  I am still using emery cloth folded up to fit into the slots, and it seems to be working good enough.  I have about another 15 or 20 leading edge ribs left to do.

Here’s the aftermath of all that deburring:

I’ll probably just keep at it with the emery cloth.  one strip seems to last a pretty good while and they are cheap.  I’m not going to waste any more time and effort on trying to use a dremel or die grinder. Thats pretty much it for tonight.  These wing rib posts are always pretty boring and simple on just about every builders online log, and I can see why.

Google Photos Link:

Hours Worked:1

Wing Rib Deburring Part 3

After discussing the use of the scotchbrite cones with folks on the forums, I decided to go pick up some emery cloth and sandpaper to deburr the gaps in the rib flanges.  Making the cones, using them and making more was taking too much time. I only have the softer 1″ scotchbrite wheels, and it appears everyone is using the harder, grey looking ones.   After driving all over Chattanooga, I finally found some emery cloth at Tractor Supply.   I decided I would gently clamp the ribs down to my bench and then use strips of emery cloth like dental floss to get into the gaps of the flanges. I cut the emery cloth into about 3/4″ to 1/2″ strips that were just wide tall enough to fully cover the flanges, and that worked out pretty good.

I was able to get about 4 or 5 ribs using a strip of emery cloth and that was being conservative.  I probably could have gotten more, but this stuff is pretty cheap, and I can make about 4 strips or more from a sheet.  I was able to get the remaining 14 inboard and outboard ribs done using this method pretty quickly.  I decided to move on to the fuel tank ribs and knock them out as well.  Using the same method as above, they went pretty easily too, but I took extra caution to make sure the leading edges of these ribs were very smooth.  The plans tells us to make sure we also smooth out the bumps from the reliefs on the leading edge flanges because there are some complex curves here.  I started out using my bastard file to work the edges and bumps on the fuel tank ribs, but soon realized I could use my scotchbrite wheel on the bench grinder to make this easier.

And it did! Using the scotchbrite wheel, I put the grinder on the slowest speed it had, so I didn’t burn through the thin metal to quickly.  This worked out great! I could smooth down the leading edges very smoothly in no time using this method.  They were really smooth, and the skins should lay very nicely around this complex curve with no bumps or roughness.

I decided to carry on and go ahead and knock out all the leading edge smoothing on all the leading edge ribs using my scotchbrite wheel.  I was able to get them all done in about 20 minutes or so.  Now, I still need to smooth down gaps in the flanges for all the leading edge ribs, but I decided I’d leave that for tomorrows session.  I ended the night on a good note, and hopefully put a dent in the rib workload.  I’ll be glad when this part of the wing build is done! HAH!.  Here’s all the photos from tonight:

Google Photos Link:

Hours Worked:2.5

Wing Rib Deburring Part 2

After taking time away from building for a few days to spend some time with my family, I found a little time tonight to work on the ribs.  I am in the process of deburring all the ribs, and at the point of deburring all the little crevices and corners of them now.  In the last session, I cleaned up the lightening holes and edges.

I had read on the Vans Airforce Forums about a trick to help with deburring.  You take a small scothcbrite wheel, cut it into wedges and then use them on a dremel to get in all the small grooves of the ribs.  I tried this tonight, but not sure I am happy with how it worked.  I may have the wrong scotchbrite wheels for this.

I gave it a shot on my dremel, and the wheel just didn’t seem to do a good job of deburring, and took a lot of work it seemed.  I worked for about an hour or so, and only got about 6 ribs done.   The wedge would only last about 1 or 2 ribs before needing to be replaced, which took even more time to cut and shape into a cone.  It kind of sucked. After about an hour, I said screw it, and decided to ask a question on the forums about which wheels they were using for this before I waste any more time on trying this.  I called it quits for tonight.  I think I got about 6 ribs done, oh well.  Here’s the photos:

Google Photos Link:

Hours Worked:1

Deburring Wing Ribs

It’s that time in the build:  Wing rib prep.  This is probably the only part of the build that most people enjoy the least.  There are 56 total ribs, and all of them need to be prepped before you can start building the wing skeleton.  That means the following things need to be done:

  1. Deburr all the flange edges
  2. Deburr all the edges of the lightening holes.
  3. Make sure al the flanges are bent to 90 degrees
  4. Flute all the ribs to make sure they are perfectly straight
  5. Scuff them and clean them
  6. Prime them.

As you can see, multiply those 6 steps times 56 ribs and you can get an idea that a lot of man hours goes into these things, and its repetitive work.  However, I figured this would be a good time to use these repetitive tasks as a sort of relaxation technique; listening to good music and just work away at them.  I do look forward to getting in the shop and doing some work with my hands, because all day long I sit behind a computer automating systems deployments for companies.  So, lets get after it!

First up, I had read from several other builders on Vans Airforce that its easier to deburr all the lightening holes using a small scotchbrite wheel chucked into a die grinder.  I decided to try it a little differently.  I chucked it up in my drill press, and then configured my drill press to run at its max speed of about 3600 RPM.  It’s not as fast as a die grinder, but it worked out pretty nicely.

I carried all the ribs out to the garage, where my drill press is, and then rocked out to some BlackBerry Smoke and deburred all those lightening holes.  These things need to be smooth because you have to reach through them during the build process to rivet skins, and do other work inside the wings.  The small scotchbrite wheels I bought are pretty soft for some reason, so I ended up going through one wheel per about 4 or 5 ribs.  I bought 100 of them so I have plenty and after about a half hour or so I had all the lightening holes deburred.

Then it was time to deburr all the flange edges. This is a process I have done many many times on the scotchbrite wheel on my bench grinder.  I deburred every single rib flange on the bench grinder and stacked them up in a neat pile for the next process.  Unfortunately, the deburring wheel on the grinder can’t get in the small gaps between the flanges, so I am will have to do those using a scotchbrite pad or some other process.  I can see that’s going to take some time, especially on the leading edge ribs where there is a lot of little tabs to debur.  I think I may give this a try, as suggested on the VAF Forums.  Thats it for tonight.  I am covered in deburring dust, I am glad I wore a respirator and safety glasses for this.  Not a lot of photos form tonight, but here’s what I took:

Google Photos Link:

Hours Worked: 2.5

Riveting the Wings Rear Spar

I found a little time to finish up the rear spars for the wings tonight.  I had let the AKZO cure for a few days while Tammy was off so we did family time during those days.  Tammy was back at work tonight, so I pulled the primered parts from the booth and riveted them together. I started out on the left rear spar since it is the one that is specifically shown in the plans.  The right one is not in the plans, and Vans assumes we know how to mirror the left for the right wing.  First thing was to cleco the doublers to the rear spar as well as the reinforcement forks and its doubler plate.

Next, we have to carefully match up which holes need rivets, as some of the holes will be used to hold the spar, doublers ribs and even the gap seals for the aileron and flaps. I used masking tape at first to cover up the holes that don’t get rivets right now and then clecoed everything together.

In the last photo above, you can see where I just used a sharpie to mark the holes the DO NOT get rivets instead of using masking tape.  After looking over the plans, we are only going to be using three different rivet sizes.  AN470AD4-4 for the thinner doubler plates, AN470AD4-6 for the reinforcement fork to rear spar, and finally AN470AD4-8 for the reinforcement fork, its doubler plate and the rear spar.  To make my work more efficient, I decided to start with the smaller rivets first, setup my squeezer for them and then do all of the 4-4 rivets on both rear spars, and then just adjust the squeezer for the next size and repeat.  So, I went ahead and clecoed the right wing rear spar parts together, making sure to mirror their orientation to the left wing.  Since there are only a few rivets on some of these doubler, I just decided to circle the ones I needed to squeeze instead of using masking tape for the right rear spar.

Then it was time to squeeze.  I started out with the AN470AD4-4 rivets and adjusted my squeezer until the rivet was setting perfectly against the rivet gauge, and the I went and squeezed all of the 4-4 sized rivets on both the left and right rear spars, always checking each one with the rivet gauge (I am picky about this). Once I had them all done, I moved up to the AN470AD4-6 rivets and did the same thing for both sides, and then finally finished up by riveting the handful of the larger AN470AD4-8 rivets. Each rivet was checked with the gauge for precision.

You’ll notice that on the reinforcement fork, I set the rivets with the manufactured head on the thickest metal.  While this isn’t technically correct, I needed to be sure I would have space to squeeze the wing skins in the holes directly above those rivets.  However, on the thick doubler plate to reinforcement fork, you’ll notice that I did indeed set these with the manufactured head towards the thinnest (rear spar channel) metal which is technically how it should be.  While there is debate on how this should be done, this will be fine since even though the rear spar channel is indeed thinner than the reinforcement fork, it is still a thick piece of metal itself.  Had I been riveting the very thin skins to something thicker, I would made sure to put the manufactured head on the skin side. Here’s the required selfie of me and the completed rear spars to help prove I actually did the work for the repairmans certificate.

And that is pretty much it for tonights session.  It was only about 1 hour and 45 minutes of work for tonight, but this actually completed the assembly of the rear spars.  They will go back on the shelf along with the main spars until I have all these ribs deburred, drilled and primed; then I’ll pull them off the shelf and build the wing skeletons. Rib prep will be consuming quite a bit of time for the next couple of weeks, so I am going to have my metal wing stands built during this time frame, hoping they’ll be ready by the time I am done with the ribs. Here’s the photos from tonights work:

Google Photos Link:

Hours Worked: 1.75

Priming the Rear Spar

Another priming day.  I really don’t enjoy priming, its probably the only part of building an airplane that I despise.  It very well could be my process, so I think I will try something different on the ribs.  However, I followed my normal routine for the spar parts:

  1. Scuff all the parts with maroon scotchbrite pads.  My goal was to not take off the alclad, but give the primer a good surface to adhere to.  I figure having alclad AND AKZO primer would give me good protection.
  2. Clean the parts with acetone.  This gets rid of oils, scuffing dust, and other contaminants that would cause the primer to not stick.  I have found I have to clean each part three times with a fresh paper towel before the paper towel comes up clean.
  3. Spray the parts with primer.

Now, this may not seem like a lot of work, but all that scuffing and cleaning is boring and very tiresome (repetitive).  I am seriously considering switching methods to the Alumaprep, Alodine and primer methods as they dont require no where near the scrubbing and scuffing.  I could just dunk the parts in bulk into tubs of the stuff and let it do its magic.

Anyways, I followed my normal procedure for now, and scuffed up all the parts, cleaned them with acetone and then sprayed AKZO.  Here’s the photos of where I had them all scuffed up, cleaned and re-marked ready for priming.

I will admit a mistake:

It’s hard to see but I only mixed up about 3 ounces of AKZO (1.5 of parts A and B). I let it have its 30 minute induction time, while I suited up.  I thought it would be enough but I learned about halfway through my spray session that it was not enough.  I was only able to finish about 90% of the parts, and I needed to go back and touch up some bare spots on the spars.  SO… thats my mistake.  I had to mix up a second batch, this time doing another 2 ounces of mixed primer and let it sit another 30 minutes to induct.  After it was ready, I finished up my priming session, and left the parts in the booth so the offgases would get ventilated outside.  AKZO has a tendency to off-gas as its curing, and its a strong smell, so they can hang out in the booth for a day or two and cure.

Of course, heres the painter selfie for proof that I did the work

Here’s all the photos from tonights work. I’ll add the rest of the photos when the parts cure and I can get them out of the booth and in to good light to snap some photos.

Google Photos link:

Hours Worked: 3.5