Lynn's RV-7 Build

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: https://photos.app.goo.gl/RiI3OipxFfTQ4UKf2

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:  https://photos.app.goo.gl/vnPTL6Qy6oCavrcl1

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: https://photos.app.goo.gl/dp5J5V1LqyJAbrTD2

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: https://goo.gl/photos/2a8y2CEpbsAxcYJ17

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: https://goo.gl/photos/Vz1KBqVCqNzYXekN8

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: https://goo.gl/photos/KaFALHx8tGPwWHn1A