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:  https://goo.gl/photos/NX9zek3fvUcWvmSR7

Hours Worked: 1.75

Prepping the Rear Spar

There wasn’t much left to do on the rear spars except finish getting them ready for priming, and then riveting.  The bulk of tonights work was deburring all the holes, so thats where I started off.  I deburred all the holes in the doubler plates (W-707E, and F), reinforcement fork (W-707G) and reinforcement doubler (W707D), and the rear spar main channel web (W-707A). Once I had both sides of all the parts deburred for the left wing, I swapped over to the right wing and did the same there.  There wasn’t much to photograph for this work, since its just deburring all these holes.

I realized I didn’t drill the holes on the flanges of the doubler plates W-707E and W-707F so I clecoe’d them to the rear spar and then match drilled using the holes in the flange as a guide. Once I had the holes drilled, I followed up by deburring them as well.

I read a little bit ahead in the plans and noticed that Vans gives us some warnings of things that we should address now before we rivet the rear spar together.  The first thing is that the outboard doubler (W-707F) needs to be countersunk for a few rivets.  After looking over the plans, I see there are 4 holes on the most outboard of the rear spare that calls for AN426AD4-5 flush head rivets.  Well, instead of machine countersinking this fairly thin metal, I decided to just use my DRDT-2 dimpler, since it would easily handle this thickness.  I dimpled the W-707F doubler and then followed up with dimpling the rear spar channel to match.

The next thing Vans warns about before riveting is that we should probably go ahead and final drill to #40 and then dimple the rear spar top flange because when we rivet on the reinforcement fork and its doubler plate, it would be difficult to dimple them afterwards. So, I broke out the drill with a #40 bit, final drilled the holes, and the used my squeezer to dimple the rear spars top flange holes all the way to the end of where the reinforcement bar would land.

I also decided to go ahead and dimple the rear spar top flange where the doublers (W-707E and F) attach just so they wouldn’t be in the way.  I final drilled to #40, and then used the squeezer to dimple the holes on the rear spar flange, as well as the doubler plate itself and made sure they still would nest together.  The squeezer very slightly bent both pieces to a 90 degree angle, where it normally is a bit more angled, so I used my hand seamers to gently bend both pieces back to their normal position.  It was a very gradual bend.  After completing all the above on both wings, I called it a night.  The parts are ready to be primed, which I will probably do tomorrow. Here’s the photos from tonights work:

Google photos Link: https://goo.gl/photos/vYgtM8yGBy4hzTXNA

Hours Worked: 2.5

Assembling the Rear Spar

Got a little bit of a late start, I had to run out to Harbor Freight after work to pickup a die grinder for the work tonight, and ran a few other errands, but I managed to put 3.5 hours in, and have the rear spar ready for metal finishing and then priming. I am at the start of the “Assembling the Rear Spar” section of the plans, and the main spars are done for a few more steps.  The session started out by deburring all the edges of the rear spar parts: W-707A rear spar channel, W-707E and W-707F doubler plates, W707G reinforcement fork and the W-707D rear spar doubler. I deburred the edges using the scotchbrite wheel, which made quick work of the parts, even the long rear spar channels.

Then, Vans has us trim away a decent chunk of the W707G and W707D doublers since this is an RV-7.  I studied the plans for a bit and then made the careful measurements, and marked the lines.  Stupid me forgot to take photos of my marks before I made my cuts, so I don’t have a good way to show how I did it, but here is the part of the plans that gives the cut dimensions:

I first decided to cut the W-707D Rear Spar Doubler first, since it would be cheap and easy to ship in case I messed it up. Note how the shaded part is angled a bit and there are 4 measurements I had to make and then mark.  Once I had my marks made, I connected the marks with a straight line using a machinists ruler. After confirming everything was right, I decided to cut it using my bandsaw with a metal blade.  This is thick aluminum, so snips was not an option and I figured I would cut with the bandsaw and then grind away any odd cuts or un-eveness from the saw.  It actually turned out really nice, and only needed a very small amount of grinding!

Once I had this piece looking right, I used it as a template for the others.  I have to make this same cut on the W-707D for both sides, as well as the W-707G reinforcement forks for both sides.  I just cleco’d the freshly cut doubler against the other pieces, and marked the edge with a sharpie, and cut them on the bandsaw.  After grinding the edges and deburring them to a smooth edge on the scotchbrite wheel, they were done.

Now that I have all my rear spar parts deburred, trimmed and ready to go, its time to start assembling and drilling both rear spars. I clamped W-707E and W-707F doublers into their locations. W707F was pretty easy, since it mounts flush against the most outboard edge.  The W-707E needed some measuring.  The plans calls out to place the most outboard edge of the doubler 50 and 3/4″ from the outboard edge of the rear spar channel.  Once they were both in place, I clamped them down with side clamps and then match drilled all the holes to a #30 after double checking all the rivet sizes in the plans.

This is the easy one!

Measuring for 50 and 3/4″

Once I had all the rivet holes drilled to size, the next step is to cut out the hole for the aileron pushrod in the doubler plate.  I flipped the rear spar over, and use the pre-punched hole in the spar to mark the location for to transfer the hole to the doubler plate.

Then, I used a unibit to drill out the largest section of this hole, and used a #40 drill bit to drill out the smaller section.  This is to get everything started so I can file, grind and trim it the rest of the way.

Once I had the holes to about close as I could get (notice there is still some black sharpie lines to be trimmed out in the photo above), I removed the double and used a combination of files (round, and flat of different sizes) and then fired up the die grind with a small grinding wheel to grind down what remained of the metal.  I then finsihed up the holes with a scothbrite pad to remove any burrs that may have been left behind. I am pretty happy with how they turned out.  They are slightly larger than the hole in the rear spar, but I think that’s fine.

Next up was to just repeat these same steps on the right wings rear spar.  I did the aileron hole a little different, but drilling even more #40 holes to make the grinding and filing go a little quicker which seemed to have help cut down on the time it took. I still used the unitbit in the larger middle-ish section which removed about 97% of the metal I needed.

I still had a little steam left, and I wanted to get these rear spar parts completed to all that was left was hole deburring and then priming, so I pushed on to the match drilling of the W-707G reinforcement fork and W-707D doubler plate.  I studied over the plans to make sure that all the holes were using a #30 drill, and then clecoed the reinforcement fork and doubler plate to the rear spar channel.  I did both rear spars at the same time since it was easier this way.  Then, lastly, match drilled all the holes to #30 on both rear spars, and marked the parts which was left and right.

Thats it for tonight.  I’ll save the deburring of the holes for tomorrow, and possibly a priming session on Sunday.  Whenever I prime these rear spar parts, I’ll also prime the tie-down brackets so they can go ahead and get mounted up.  Here is all the photos from tonights work:


Google Photos Link: https://goo.gl/photos/Yjaue9L3JMiy9Jgf9

Hours Worked: 3.5

Tiedown Fabrication

I actually fabricated some parts from the plans tonight.  This section of the plans has us fabricate the tiedown brackets that bolt to the main spar and help secure the aileron bell cranks as well.  There was a good bit of fabrication from raw materials so it was pretty much, but just a bit slower than I usually work.  I started off by tapping the holes in the AEX tie down stock for a 3/8 x16 threaded eye bolt. I had to actually run out to Ace hardware and pickup a tap and tap handle to get this done, so I did that while I was grabbing some dinner.  The plans calls for us to go 1″ of depth, so I wrapped some tape around the tap to mark 1″, and clamped the AEX stock to my work bench to start the process.

Almost finished with tapping this one

I have done this process before on other projects, so I lubed up the tap with some Boelube and slowly worked the tap into the AEX stock making sure it was straight.  I gave it a few twists into the metal, and then backed the tap out to clear some of the chips. I kept repeating this advance and retreat process until I had the full 1″ of depth as called for in the plans, and then did the second piece of AEX stock for the other wing.  The reason I did this first was so that if I messed up tapping the metal, I could just flip the piece around and use the other end, since both ends are identical.  Once I was happy with the threads I trimmed the 1/32″ of an inch that Vans calls for in the plans.  I am not sure why we need to take the AEX stock down from 7 and 16/32″ to 7 and 15/32″ using a bandsaw very carefully and then finishing it on the bench grinder.

New threads are kind of hard to see in this photo, but they are there!

Next up was to fabricate 4 spacers to fit between the tie down bracket and the main spar. These are called W-726 and the plans has a full size drawing of what they are supposed to look like, so they are easy to make from the AB4-187×1.25 stock.  I measured them out for 2″ on my bandsaw and cut them out.  The next process was to mark the center and then drill the lightening hole using the drill press and a 1″ bi-metal hole cutter.

After I had the lightening holes done on all 4 of these parts, I was happy with them and moved on to finishing their edges.  I ran them on the bench grinder to round the corners, and then deburred the edges nice and smooth on the scotchbrite wheel.  Then I deburred the lightening hole to make it smooth. They were ready to be match drilled with the tiedown bracket and main spar.

This next part required a bit of measuring, squaring up and clamping to make sure everything was perfect.  We first start out by drilling an index hole in the AEX tie down stock to be used to help guide it onto the main spar for easier back drilling.  The plans calls out the dimensions, I marked it up and drilled it on the drill press to make sure it was perfectly square, and then repeated the process for the other tiedown.

Then I used masking tape to hold the spacers on the main spars while I positioned the tiedown bracket and squared it up with the spar web using a square, using the index bolt to help with alignment.  Then I clamped it all down and back drilled everything using a #12 drill bit.

Once I was happy with the left side, I repeated this same process for the right. As I drilled a hole, I would stick a AN3-7 bolt into the holes to make sure nothing moved during drilling.  There is some tight tolerances here, and it holes the aileron bell crank, so its pretty vital this is done right. The next step is to drill for the 4 nutplates that secure the W-726 spacer blocks to the AEX tie down bracket.  This is pretty clever, as Vans has us put the nutplates on the tiedown bracket and then rivet the spacers to the bracket, that way if you never need to replace the nutplate for any reason, its as simple as just removing the entire bracket and replacing it on the bench instead of having to drill the main spar!  See below:

So, theres a couple ways of drilling these nutplates.  The route I chose was simple, and didn’t require any special tools.  I simply took a couple of AN3-6A bolts and ran them into the tiedown bracket and spacers and threaded on a nutplate to use as a jig for my drill holes.  This nutplate would be sacrificial, since its going to drill all 8 of them, but there are extras. Once I drilled the first hole, I clecoed the nutplate and used the bolt and drilled the second hole.

Yes, this nutplate is on backwards, but it doest matter since I am just using it as as drilling jig!!!


Once all the mounting holes were drilled for the nutplates, it was time to countersink the backs if the W-726 spacers for the flush rivets.  We use flush rivets here because these spacers need to sit flat against the main spar with no interference on this side.  I chucked up my microstop with a #30 pilot countersink and then countersunk all the holes in the spacers.

Notice my “CS” marking so I know which side to countersink 🙂

After I had all the holes drilled, it was time to go back and deburr every hole (except for the ones we countersunk, duh!).  I deburred the holes in the tiedown bracket, the spacers and the spars.  I also deburred the edges of the AEX tiedown stock as well and rounded the corners to prevent cuts and scrapes in the future, using the bench grinder and scotchbrite wheel.

In the plans, Vans tells us to go ahead and rivet these spacers onto the Tiedown brackets but doesn’t mention priming until the very end of this section, where it appears they are talking about priming the entire tiedown assembly (with attached spacers).  I figured these bits of aluminum are both very thick, and will be away from moisture, so I didn’t prime them before riveting them together.  I will, however, prime the entire assembly before I mount it permanently, just to be safe. That will only leave the two surfaces of aluminum that are riveted together (facing each other) not primed.  I think it will be alright.

Riveting these together is your standard procedure for nutplates.  Cleco one side, rivet the other and repeat across all the other nutplates.  I used a squeezer because why not?  They turned out great!

Completing both of these tiedown assemblies to this point was about 4 hours or more of work, so I called it a night.  I’ll drill the hole for the stall warner tomorrow, and may even go ahead and prime these.  I am going to go with a Dynon panel, so I will need to order the servo mounting kit because in one wing, the servo attaches to the aileron bellcrank, which then bolts to this tiedown bracket. I’ll get that on its way this week, and a few other odds and ends as well. Here’s all the photos from tonight:

Google Photos Link: https://goo.gl/photos/sPF5MJKnv1kmqRoZ6

Hours Worked: 4.25

Countersinking Nutplate Screw Holes

I was able to wrap up all of the fuel tank attachment nutplates and the inspection cover nutplates tonight.  In the last session, I installed all of the nutplates, and tonight I finished them up by machine countersinking all the screw holes to accept the dimples in their mating metal.  The work started out by first setting up my microstop countersink with a #30 pilot in the #8 nutplate screw holes.  Van’s has a pretty good tip on getting this depth correct:  Cut the head off a #8 screw and use it as a guide.  Once the screw head sits flush with the surface, go a few “clicks” deeper with your microstop so there will be enough depth for the dimpled metal.  Here is my homemade “gauge”:

It worked really well.  A lot of builders go out and do some weird things using dial calipers, and other extremes, but the main spar has a lot of metal and so long as you go just slightly deeper than the screw head, it’ll be perfect.  Here’s a good shot showing how it looks with my “gauge”

You can just barely see the fresh aluminum around the head of the screw. To give it a really good test, I used some scrap sheet aluminum the same thickness as the tank, drilled and dimpled a #8 screw hole in it and made sure it would nest into the countersunk hole flush.  It did, so I locked my microstop down at that setting and countersunk all the other fuel tank attach screw holes on both spars.

The next bit of work was to countersink the screw holes for the inspection cover nutplates.  Theres three inspection covers on each of the underside of the wings, and the forward 4 holes are all attached to the main spar with #6 screws and nutplates. I did these pretty much the same way as the #8’s above.  I cut the head off a #6 screw and used it for my gauge, then set my microstop a few clicks deeper and countersunk a test hole.  Then I grabbed one of the inspection covers, drilled it to size, dimpled it and laid it across the spar to make sure it seated flush against the spar.  I had to tweak the counterisnk a few more clicks deeper, but finally ended up with a nice flush fit, and then locked it down to do the remainder of the holes in both spars. Heres how the inspection cover looked against the spar:

Finally, the last thing to do was to prime these new countersunk holes.  The spar ships anodized, and drilling the countersinks leaves the metal in those spots open to corrosion. Vans recommend that we prime these spots to prevent corrosion.  So, I mixed up 10 mL of AKZO (5 mL of each of the two parts) and let it sit the required 30 minutes for induction.  In hindsight, 10 mL was a bit too much, I probably would have been just fine by mixing about 5 mL total.

Yep, thats a high tech paint applicator and mixing cup…courtesy of Q-tip and Gerber baby food. I used about 5 Q-tips to apply the primer after it had inducted, and the worked well enough.  I got a little messy with the application on purpose, as I wanted to fay the primer out from the holes to ensure there was no edges that moisture could penetrate.

I made sure to get decent coverage on all the countersunk holes, and then called it a night.  I’ll let this stuff cure until tomorrow and then start another session.  It looks like I’ll be building the tie-down brackets!  Here’s all the photos from tonight:

Google Photos Link: https://goo.gl/photos/4s2RkHuLaTHUK2Wt7

Hours Worked: 4.25

Attaching the Main Spar Nutplates

Nut Plates….tons of nutplates.  I worked a good 3 hours tonight on nothing else but riveting the nutplates to the top and bottom of the main spars.  I think there is something like 150-ish total of these little things that need to go on.  I need to get these guys riveted on so that I can use the nutplate hole as a guide for the pilot on my countersink.  Then I’ll be able to countersink the last of the holes for the tank skin dimples and attaching screws.   I did have a helper tonight though:

The work started off by clecoing the K1100-08 nutplates to the main spars, taking careful note of which pre-drilled holes the go into.  There are a few other pre-drilled nutplate holes for a K1000-06 nutplate to attach the inspection cover, but we will get them after these fuel tank attachment nutplates.  This is a pretty straightfoward process of just lining up the holes of the nutplate and inserting a cleco into one side to hold it.  Once I had them all cleco’d into place, I came back and dropped in a AN426AD3-4 rivet in the other hole.


I did this one spar at a time so I could keep up with which part goes where on these spendy main spars. Once I had one side of nutplates all clecoed, I followed it up by squeezing the rivet with my squeezer.  This is quick work, but patience was used just because I didn’t want to mess the spar up.  Once I had the first rivet set, I went back, removed the cleco and set the second rivet spot checking the all rivets with a rivet gauge.  Once I was happy with one side, I flipped the spar over and did the same on the opposite side (top/bottom). Then I repeated this same procedure exactly on the other main spar.  The rivets look really great when set:




After I had done all the tank attach nutplates, i moved on to the inspection plate attachment nutplates which are located on the bottom of the main spar flange, at 4 stations.  These guys use K1000-06, which are slightly smaller for a #6 screw (the tank attach nutplates are for a #8 screw), so I saved these for last so as not to confuse them with the wrong nutplate. The procedure was exactly the same as for the tank attachments, even down to using the same size rivets, and I completed it for both main spars.

Once I was happy with those few little nutplates, I decided to go ahead and attach the last 4 for the main spars (well until we do the fuel tanks down the road).  These are for the center section attachments points and they are facing in a different direction so as to allow the doubler plate to fit flat against the reinforcement bars of the center section.  I read the plans very carefully to make sure I had them in the right orientation.  Attaching these is the same process as all the others, except that they use an AN426AD3-6 rivet, a bit longer to go all the way through the thick doublers on the main spar.  I also had to swap out the yoke on my squeezer to the 4″ so I could reach them without any problems.  They turned out great:


Heres a neat shot of all the nutplates fully attached to both main spars, and even a selfie to prove that I am the guy actually doing the work 🙂

That wrapped up the session for tonight.  That was a solid packed 3-ish hours of nutplate attachin’ work.  It feels good to be back to building after the 8 week hiatus waiting on the wings to get here.  Heres the photos from tonights work:

Google Photos Link:  https://goo.gl/photos/GhzP7Qx9gVTzQsoW6

Hours Worked: 3

Started the Wings! Countersinking for the Nutplates

Today marks the official start day for the wings! I have been studying and reading over the plans since the wing kit came in last week. After getting the shop organized and setup for the wings, I decided tonight was as good a night as any to get started.  Of course, the first thing Vans has you do is go drilling and countersinking hundreds of holes on these gorgeously expensive Main Spars.

The plans has us first attaching the nutplates for the wing tanks.  The wing kit instructions are very…..spartan.  We are told that at this point, Vans expects us to know how to do things so instructions are basic workflow guides.  Luckily, the empennage kit prepares us really well for the work and I am now pretty comfortable at reading the plans to find out what rivets, nutplates and orientation they need to go.  The first step is to tape up the gap between the spar flange and the spar bar / doublers to keep drill shavings from going in and causing damage.

There is A LOT of holes for these things.  I think its somewhere around 150 holes that need to be drilled and countersunk.  I started off match drilling all the mounting holes for the K1100-08 nutplates.  They use AN426AD3-4 rivets, so I drilled them all to #40.  Reading ahead in the plans, I also noticed that I need to also drill #40 holes for the K1000-06  nutplates that attach the W-822 access plates to the main spars, so I got those holes done as well. I started on the left main spar, then moved over to the right main spar to do the same.

Next up was the countersinking.  I chucked up my microstop countersink and put in a #40 bit.  I backed the countersink all the way out and worked my way up on a test hole until I had the correct depth, then countersunk the first hole in this expensive piece of aluminum.  I dropped in an AN426AD3 rivet to see how it fit, and a few more clicks of the microstop had it at the perfect depth.  Then I done the rest of the bazillion mounting holes for the nutplates on both spars.

Test rivet fits so snug and flush!

You really have to be careful doing this as there are tons of holes, and the diagonally mounted nutplates in the wing walk area can make you scratch your head a bit.  Having done all those, I decided to do the next sets of nutplates which is on the front of the main spar, where it mounts to the center section.  I gave the plans a good study to make sure I was correct on their orientation (the K1000-4  nutplate itself  gets mounted on the forward side of the main spar), I match drilled #40 and countersunk the AFT side of the both main spars.

After 2.5 hours of drilling and countersinking all these holes, I decided to call it quits for the night.  I still need to countersink the actual screw hole for the nutpates, but can’t do that until I have the actual nutplates riveted on to the spars.  That will be a good place to start for the next work session. I noticed there are three more holes for nutplates in the spar doubler, but I am not sure what they go to.  I will look the plans over tonight and get them tomorrow.

Here’s all the photos from tonight:

Google Photos Link: https://goo.gl/photos/VUijFaG5YJes4sqi6

Hours Worked: 2.5