Well, the CPR class after work didn’t happen today.  The class was sponsored by my office, but we’re in the news business, and the stuff up in Boston caused some technical problems with us.  Since most of the people who’d signed up for the class were busy handling that mess, the class was pushed to tomorrow night.  I’ll be honest…I didn’t really want to go work on the ribs tonight.  I think it still seemed like a big tedious task, and it was easier to just procrastinate.

But I didn’t do that.  I went out and got to work anyway, starting with the right wing leading edge ribs.  The process is pretty straightforward: bend the flanges to a nice right angle with the rib face, and flute the ribs to take the bow out of them.  I decided to take extra photos tonight to help document this process.

This is a shiny, new, untouched rib.  Notice how the center of the rib isn’t even touching the table due to the bow caused by the forming process.  This isn’t going to work; the rib needs to be straight.

Some work with the fluting pliers pulls the rib back in line:

The flanges are also frequently not square:

But a little work the hand seamers brings them back into line:

Of course, it gets a little more complex than that in the curved portions of the leading edge ribs.  See, fluting the flanges also tends to bend them relative to the face, and bending them tends to change the fluting job.  In practice, I found that the best procedure for the leading edge ribs was to flute first, then go back and bend the flanges square, then go back and fine-tune the fluting before making one final check of the flanges.

Josie came out and got some photos of me slaving over the ribs.  Bending flanges:

And checking squareness:

So yeah, 90 minutes and I managed to prep exactly six ribs.  The good news is that the leading edge and tank ribs should be the tougher part of this job; their curved profile means lots more distortion.  The main ribs should be comparatively easy.

After that tedious work, I decided it was time for one of those temporary assembly tasks that serves no purpose except to give me hope.  In this case, I clecoed those newly prepped ribs to the leading edge skin.

That’s it for tonight; maybe I can get to work on the right tank ribs later this week…

I’m a little disappointed in myself for not being very productive this weekend.  I did finally start getting my feet wet with prepping the wing ribs, but that seems like kind of a daunting task.

I started out today by riveting the remaining rear spar.  This kind of work I can roll on all day long…it’s straightforward and the results are obvious.  I did, however, manage to mangle my very first rivet, so I had to drill that little bugger out and replace it.  But I got the rest of the rivets shot, and that left me with the decision of where to go next.  I’ve really been putting off this whole rib prep thing, but as of that moment, there wasn’t anything else to do.

So I pulled out all the ribs and set them out on the workbench:

Step A was to deburr the edges.  For the long edges, I fired up the bench grinder and went to town for what seemed like an eternity.  Actually, it really wasn’t that bad, but it was definitely getting tedious already.  Next, I went after the lightening holes with a small scotchbrite wheel in my die grinder.  Side note: Extended use of the die grinder pretty much equals extended running of the air compressor.  It doesn’t take long with that thing to trip the pump, and apparently the pump can just barely outpace the die grinder’s air usage.

Okay…now what?  I still needed to work on the edges in all the little cutouts, like at the corners of the ribs and the tip of the nose ribs.  Problem is, most of those holes are too small for my files to get into effectively.  I think it’s time to invest in some needle files for getting into these tight spaces.  Okay…if not that…I guess I’ll start looking at straightening the flanges.

The intent of this operation is to ensure that all the rib flanges are at right angles to the rib face.  This will help ensure that the wing skins sit nice and flat.  This, along with fluting the ribs to remove any bowing induced by the forming process, seems to be regarded as one of the more dull and time-consuming tasks of the build, and I can see why.  I set one rib out, grabbed a small piece of aluminum angle to use as a square reference, checked the rib…hmm, this seems pretty good actually. I tweaked the flange a bit with the hand seamers to make it even better, but suddenly I felt like I wasn’t sure if I was doing this right.  The angle piece I was using didn’t really sit flush against the rib, and I was skeptical if its usefulness as a reference.  I just felt like I needed to do some reading on this subject before diving in.

I feel like this is probably some combination of generic do-it-right jitters with my procrastinatory nature.  Faced with a tedious task, I found an excuse to stop, go in, and do some research.  And then I found other things to occupy my time, such that I didn’t go back out in the garage again.

On the one hand, this is particularly annoying to me since my free time is limited in the near future.  I’m doing CPR classes after work three days this week, and the next two weekend are booked up with other activities.  On the other hand, maybe it’s better for me to attack this rib prep in small doses, instead of trying to bang out a ton of them over the course of a Saturday or some such.  At any rate, I’m just going to have to push through…at the end of the tunnel, I’ll have an assembly that looks like a wing skeleton.

Which reminds me, I’m going to have to build my wing racks at some point here too…

Another short evening in the shop due to other stuff going on, but doing something is better than nothing.  I started with bolting the tiedown brackets onto the main spars.  Nothing complicated here, just plain old nuts and bolts.

Tiedown bracket in place:

Torque seal on the nuts.  These will be visible through one of the inspection panels under the wing, so I can make sure nothing is working loose:

Then I went to work riveting the right rear spar.  I had previously taped over rivet holes that needed to wait for other parts; luckily, I double-checked the plans before starting to rivet, because there were some holes I forgot to cover on the small reinforcement plates.  In fact, there were relatively few rivets on those plates that could be set right now.  The reinforcement fork, on the other hand…most of those go in place now.

Reinforcement fork: (the end closest to the camera will eventually bolt into the fuselage)

Inboard aileron hinge reinforcement plate.  Note that most of the holes remain unriveted:

That completed riveting on the right spar.  I guess tomorrow I’ll knock out lefty, and then it’s going to be rib prepping time…

Josie and I had a dinner date for her sister’s birthday, so most of the evening was booked up.  Still, after we got home I decided to go play in the garage for at least a little while, just to keep my hands on the project.  I clecoed all of the rear spar components together so they’d be ready for riveting maybe tomorrow night.  Some of the rivet holes need to stay open for ribs and other such stuff, so I taped over those to keep from riveting them.  Then I got the assembled tiedown brackets and went ahead and tapped them for the tiedown rings.  I had kind of wanted to get them bolted onto the spars, but I decided it was too late and called it a night instead.

No pictures, not much to see really.

I made a point of bailing out of the office right after 5 today so I could get home and finish priming those pesky rear spar channels.  After a quick stop at the farmer’s market for some dinner materials, I was home…except then I spent more time than I expected prepping for dinner.  No worries though, I still made it outside with plenty of daylight left.

I wanted one more coat of 7220 on the side of the spar channels I’d started Sunday, so I went ahead and shot that, then moved inside to work on the tiedown brackets. They were all primed and ready to go, so I clecoed everything together prior to riveting.  Even though I’m careful about marking all the parts, I checked them for proper fit against the spar just to be really sure before I started squeezing rivets.

I only had one hangup here-on one of the nutplate rivets, I got a little sloppy with the squeezer and the flush head ended up sticking up a bit.  Hooray, a drill-out!  As i calmly went to work on it, I thought back with some amusement to the time when drilling out a rivet was sort of sweat-inducing.  Of course, that pretty much guaranteed that something would go wrong.  After popping the head off the offending rivet, I start hitting it with the punch.  About the time I was thinking “I should be careful not to bend this nutplate,” I bent the nutplate.  So now I needed to drill out the other rivet and replace the nutplate…and apparently the other rivet was the most securely-set rivet I’ve ever done.  I went to town on that thing with the hammer and punch, to no avail.  Finally I hit on an idea – I got the rivet gun out with the flush set, and used that to hit the punch.  That got the thing out finally.

With all the rivets set, I walked back over to the spars for one final test fit.  Strangely enough, now the brackets didn’t want to fit between the spar reinforcement bars.  Hm.  I think when I checked before, the presence of the clecos prevented me from getting the assembly fully seated, giving me the false sense that the fit was fine.  Oh well, no big deal…I put each assembly in the bench vise and used the vixen file to shave a bit off the edges of each spacer, checked again, and everything fit fine.  Then I got to shoot primer on them yet again.

The brackets, after filing:

And with even more primer:

Meanwhile, the spar channels were dry enough that I flipped them and sprayed the other side.  I think these are finally ready to roll…that’s keep me busy one night, riveting the reinforcements into those channels.

Finally, primed spar channels:

In other news, I called Van’s on Monday about my backordered parts.  They’d just gotten in the tank rib, and had one batch of nutplates ready to go.  The tank attach nutplates, on the other hand, they still didn’t have.  Seems they’re having some issues with their supplier, and the expected ship date for those is around the beginning of May.  But they went ahead and shipped the parts they had on hand.  I guess I’m going to have to stop procrastinating and start taking care of ribs, since I’ve got some more time on those nutplates.

Yup, basically all I did today was deal with primer.  The afternoon was pretty busy for us since it was the first race of the MotoGP season; I’m a pretty strong fanatic and I’ve got Josie thoroughly hooked as well.  So some time had to go to that.  In between, though, I was able to take care of most – but not all- my priming issues.

First off, I decided to work on some of the rear spare reinforcement pieces.  While not as widespread as the spar channels, I had a touch of primer flaking on the reinforcement pieces as well.  I wanted to use those pieces as a test for my “fix” before going to town on the spar channels.  I started by sanding down the flaking areas, getting rid of the flaked areas and feathering out enough that I was removing what looked like well-adhered primer.  Then I cleaned the areas well with a tack cloth before shooting another coat of SEM.  This ended up working pretty well, though I didn’t know that until the end of the day.

Meanwhile, I moved on the priming the tiedown bracket pieces.  I’d already cleaned these pieces earlier and set them out in the sunshine to dry.  Since the pollen was starting to appear, I hit these pieces with the tack cloth as well before priming.  I also used NAPA 7220 on these; I decided from comparing in the past that 7220 was what I wanted to use in the future. (I only used the SEM on the spars because I had it and didn’t want it to go to waste)  There was no problem with the 7220 on these pieces at all.

Finally, it was on to fixing the rear spar channels.  I figured I didn’t have enough SEM to recoat these, so I decided to just sand them down thoroughly and reprime with 7220.  Unfortunately, I only had one can of 7220 on hand, and it went empty before I even got one side of the channels fully primed.  And since NAPA keeps bankers hours, there was no way to get any more, so that was pretty much the end of the day.  I’ll plan on picking up some more primer tomorrow and hopefully finishing up the spar channels tomorrow night.  Then I can finally get to riveting some stuff together!

I also want to maybe call Van’s tomorrow and see if I can get an ETA on my backordered parts.  Straightening and fluting the ribs is a pretty big job I could be getting started on, but I kind of would like to have all the ribs on hand before I get going on that; I like to do things in batches.  Though I guess I could just start working on the main ribs and then the leading edges, and leave the tank ribs for last, since that’s what I’m missing…but in any case, it’s been almost four weeks now since I got my wing kit, with no more information on the backordered parts.

I kind of wish I’d kept going on these tiedowns last night, because there was very, very little left to do on them.  Tonight I just clamped the nutplates in placed, drilled the rivet holes for the nutplates, and countersunk the backside of the spacers for the nutplate rivets.  Pretty simple, and not very time-consuming.  After just over half an hour, the tiedown brackets and spacers were ready to be cleaned and primed.

I guess I’ll be doing a lot of priming this weekend; I’ve got these pieces, and I still have to sand down and reshoot the rear spars that I had primer flaking off of a couple weeks ago.

Started the night by getting the drill press and band saw properly bolted down to the table.  It looks like a real workbench now!  Once the admiring part was over, it was time to get to work on the tiedown spacers.  The pieces were already cut to size, they just needed a lightening hole added before they got drilled in assembly with the tiedown brackets and spars.  The plans call for a 1″ diameter lightening hole, but the problem is I don’t really have anything that will make a hole that size.  A fly cutter would be handy for this, but…yep, don’t have one.  I decided instead to just make the hole 3/4″, since that’s the biggest hole my Unibit will make.  I figure the extra weight caused by making the hole smaller is pretty negligible.

The drill press worked like a charm for this stuff.  First, I marked diagonal lines between the corner of each piece to find the center.  Then I put a 1/4″ pilot hole in each piece, and followed with the Unibit.  The spacer material is a bit thicker than the depth of a step on the Unibit, so I had to actually drill from both sides to get the hole even.  Once that was done, I used a sanding drum on the Dremel followed by emery cloth to smooth out the interior of the holes.  A pass with the deburring tool on the edge of the tool and they were ready for drilling!

I made a lot of aluminum chips during this process:

The completed spacers:

The tiedown brackets are match drilled to prepunched holes in the spar itself.  The plans give dimensions for making a single locating hole in each bracket; these I drilled using the drill press.  Next, a bolt is dropped through that hole and the spar to locate the bracket, and a square is used to position the bracket in place and clamp it down.  The spacers I made before go between the brackets and the spar; I used some blue masking tape to hold them to the spar while I was lining up and clamping each bracket.  Then the spar gets flipped over and it’s drilling time!

That done, I laid out the parts on the bench (labeled so I know where everything goes) and looked back at the directions.  Next step is to drill the spacers to the brackets for the nutplates that will be used to attach the aileron bellcrank.  The spacers will be riveted to the brackets and nutplates, that assembly will bolt to the spar, and the the bellcrank will blot to that assembly. (whew!)  I kind of wanted to keep rolling, but it was past 10:00 and the air drill and compressor aren’t exactly the quietest things on the planet.

I settled for clamping one bracket/spacer assembly together before calling it a night:

Well, I tried to get some good work done on the tiedowns today, but it didn’t really work out.  First, I had to fabricate four spacers; the tiedown hardpoints themselves sit against the spar reinforcement bars and attach there with bolts.  However, the aileron bellcranks mount at the same location on the other side of the spar, and bolt into nutplates that will be riveted onto the hardpoints.  Since these mount points are inside the spar bars, the spacers go in there.  They’re pretty simple, just 2″ lengths cut from bar stock, with a 1″ lightening hole cut in the center.  They get drilled in assembly with the spar and hardpoint.

I made the first cut using the bandsaw…but apparently I need to replace the blade on that, because it really doesn’t want to cut straight, and wanders pretty badly.  I tried playing with the blade tension to no avail.  As such, my first cut produced a piece that was worthless.  So I made the rest of the cuts using the good old hacksaw, and then cleaned the cut edges up on the grinder.

At this point I had an odd sort of internal debate; the plans call for 3/16″ holes for the AN3 bolts, so I grabbed a 3/16″ bit from the drawer.  I went to check it against the predrilled holes in the spar and was kind of surprised when it didn’t fit.  Hmm, are the holes drilled undersize?  I wanted to be sure, so I got an AN3 bolt…huh, it drops right into the hole.  Even more odd.  Then I got the 3/16″ bit from my El Cheapo bit set…it drops into the spar holes OK.

I decided to drill a hole in my scrap piece using the apparently slightly oversize bit to see how the bolt fit in the hole.  The results sent me in a very different direction; while the bolt fit OK without a ton of apparent slop, the hole I drilled was kind of ugly.  Seems like it’s tough to keep the drill straight while going through thick pieces like this.  So I decided it was time for a drill press before I went to drilling these pieces.  After a little research, I settled on a model sold at Lowes.  

When I got there, though, the parking lot was oddly empty, despite it being about 6:30 and the door stating that they were open until 8 on Sunday.  An employee in the parking lot explained it to me…they closed at 6 due to it being Easter.  Ohhhh…well, so much for getting my drill press today.  Guess I’ll stop by again after work tomorrow.

So I just went ahead and knocked off for the day.  More to come tomorrow…