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It takes time to deburr the ribs and stiffeners. Partly it's learning techniques, going over the pieces several times until they are consistent. Partly it’s summer. But this marks about a year on the project. Maybe pick up the pace a little?
Before deburring I needed to form some new pieces to replace defectives. Mostly cracks created when pressing the lightening hole flanges. Now I realize I should have deburred/smoothed the lightening holes before pressing the flanges. The fly cutter did leave some roughness. Smoothing before pressing the flanges would have stopped the cracks.
Probably a point in favor of the router method of cutting lightening holes, since the router cuts more smoothly. But the fly-cutter method has certain advantages. At any rate, other builders would be wise to smooth their lightening hole edges before flanging since the metal gets stretched when pressing the flange.
Also, part of the process of prepping these pieces was to check and fine-tune the flanges to 90 degrees and tweaking for maximum flatness/straightness. It occurred to me that if I have to bend things to make them fit upon assembly, then I might be inducing or storing stresses in the structure. Better to minimize that sort of thing by making the pieces as straight as possible to begin with.
Not satisfied with deburring tools. They create a beveled edge on drilled holes if enough pressure is applied to remove the burr. That amount of pressure would also cause the tool to sometimes catch and create a little nick. So I adopted the strategy of going over the pieces lightly, with just enough pressure to remove some of the burr bot not enough to cause a bevel or a nick.
The real deburring was done by Scotchbrite wheel, a few different grades of Scotchbrite pads and 320 grit sandpaper. The Scotchbrite wheel works fast with little effort. Even some of the lightening hole edges are reachable by the wheel. But the bench grinder needs to be respected since it can grab your piece from you and throw it across the shop. Getting close to edges and into tight areas I used a small rotary tool and Dremel wheels, and also cut Scotchbrite pads to fit onto a hand-drilll mandrel.
My EAA Technical Counselor paid a visit and said it was good, though he found a few tiny lips and curls to be smoothed. A fingernail will find the burr where a fingertip will not. The noses of the nose ribs will be removed, and the fore/aft edges of ribs will be cut to length upon assembly, so those edges are not smoothed.
After this, the next steps will be: clean with soap to degrease - etch with Ekoetch - light coat with Ekoprime.
Youtube video to show progress:
https://www.youtube.com/watch?v=uFzPv1zLK2AComment
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Looking good Frank, I think you will have a fine set of wings!!!Comment
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Prepared the ribs and stiffeners for paint by first removing ink and residue with acetone, then washing with dish soap, and then scrubbed with Ekoetch 2:1 using medium Scotchbrite pads.
The paint is Ekoprime diluted 10% with distilled water and applied using a HVLP electric sprayer. Ekoprime settles in the can quickly and needs to be stirred often. A solid sludge will form in the can after just a day or so.
The weight of the paint adds an additional 4.35%. This was calculated by weighing the nose ribs before and after painting. I’ll repeat this on other wing parts to see if this holds true.
Practiced riveting using the bench-mount squeezer from aircraft-tool.com. Made some practice pieces which were riveted, drilled out, then riveted again.
Riveted rib stiffeners to nose ribs. The bench-mount squeezer gives consistent results.
Here are a couple of short videos which highlight the steps:
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This gallery has 20 photos.Last edited by Frank; 11-16-2021, 07:04 PM.Comment
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Finished riveting the rib stiffeners. The ribs are now ready for assembly, except most if not all ribs will be trimmed for length (depending on location) and the nose ribs leading edges will be trimmed after fitting the skin. Also there will be some paint touch-up to do, mainly on cut edges.
Riveting the rib stiffeners is likely the easiest riveting for the entire project; bigger challenges to come. But the bench-mount squeezer makes this step a breeze. I fabricated a bracket mount for the narrow yoke (which came with the squeezer kit), to make it fit inside the smaller lightening holes.
The rivets themselves are pretty consistent. Important to keep the work square to the dies. I have marked just a few to possibly drill out. I will try to get my EAA Technical advisor in soon to check my work and talk about tolerances.
Here's a link to a short video which hits the highlights:
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This gallery has 5 photos.Last edited by Frank; 12-12-2021, 06:43 PM.Comment
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Those ribs look like factory Frank, You do great work. When I built my Rv4 wings I used the scotch brite wheel but I used it in my drill press with the horizontal orientation. That also seemed to work well. But as you said if not careful it would snatch it out of your hand and throw it across the shop.Comment
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Milestone achieved with the bending of the spar C-channels and joggling the ribs. I should have followed Dave Clay’s plan (google: dave clay bending brake) more closely in some respects. Immediately discovered two four-foot nickel steel hinges were inadequate. Replaced with one six-foot stainless steel hinge (with two one-foot pieces of the nickel steel cut for the ends). Need that single solid piece across the middle. The straightest of the 3x3 steel angles was used for the bending edge (there was some bowing of all the pieces). Though the apparatus flexes a bit under pressure, it has held up well. The results look good to me. EAA Technical Counselor is on the way to check it out.
The aluminum sheets from Aircraft Spruce had some pretty heavy wrinkles and folds in the plastic film. A couple of edges weren’t covered at all. Rather than deal with the annoyance, I replaced a lot of it with protective film from the art store.
Though the 032 wing parts could fit on two 4x8 sheets, I bought three sheets and glad of it. I had a couple of sad results before establishing a ‘method’.
The joggling was easy after the joggle blocks were made. Paint on the inside of the joggle tended to come loose. Will take care of that and touch up the paint after the ribs are trimmed to length.
A short video covers the highlights:
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Reality check: approximately 20 months into the project and total expenses are close to 4500.00.
Not captured in the pie chart is 262.00 for Stewart Systems. But there are a few non-project household expenses included.
The total does include the 12 foot cap strip material and its expensive shipping.
But still a few hundred dollars yet to spend on wing materials and tools.
Time spent on the project so far is roughly 1440 hours, based on 18 good months (72 weeks) of 20 hours per week.
I'm 68 years old and in good health. Colleen and I live on Social Security and retirement savings.
The expenses so far have been pretty well covered by our monthly budget.
Looks like the entire airframe can be constructed at this slow pace and rate of expense.You do not have permission to view this gallery.
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Ailerons are complete at this stage. Upcoming will be the addition of steel parts, alignment of trailing edge to the wing trailing edge, and fabric covering. And aileron hinge covers.
With more bucking experience and customized bucking bar, I will go back and replace or upsize a few rivets. So far I replaced/upsized maybe four rivets.
Pop rivets feel tight. Dimpling for the flush rivets enlarges the hole. Some of the shop head of solid rivets don't look exactly like the textbook diagrams.
There is a small pile of rejected pieces. Mistakes were made, even though the plans clearly state "Don't screw up".
Here is a five minute video:
https://youtu.be/88XLh21KJmgYou do not have permission to view this gallery.
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Hey Frank. that is a good looking set of ailerons. Keep up the good work and keep the pix coming, im sure Ill be referring back to them when I start my wings.Comment
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The wing spar webs and cap strips are laid out and marked. The lightening hole centers are marked. Aileron bracket holes marked.
The do-not-drill locations are marked.
Time to start cutting and drilling!
But which to do first: drill the cap strips or cut the lightening holes?
References here on the forum and elsewhere show builders mark and drill their cap strips (and spacer bars) first.
Then the lightening holes are cut and flanged (22 out of 35 on the LSA rear spar).
Another idea is to cut/flange lightening holes first. Then deal with any resulting warpage. One builder said this is what he did.
On the other hand, I can see building up the structure first, get it aligned and fixed. Then go in and cut out the excess weight.
Maybe no difference. Maybe just a matter of ease of material handling.
Just another happy puzzle!You do not have permission to view this gallery.
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Regarding the LSA .032 root center ribs (no. 1 position), I talked to Bob and he said it is not necessary to flange the lightening holes.
"You don't need to. You can if you want but it's a lot of work."
My own reading of the plans led me to that conclusion also. But I see that factory kit wings do have those holes flanged. Some LSA builders have flanged theirs, some have not. Having visited another LSA builder a few years ago, I see from the pictures I took that he followed the plans and did not flange those .032 lightening holes. I will do the same.You do not have permission to view this gallery.
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