Ruined trim tabs and first elevator rivets

Well today I tried to bend the tabs on the ends of the trim tabs and things didn’t go well. On my first attempt the wooden blocks I used dented the skin pretty badly on one side and the tape didn’t want to come off very cleanly. Rubbing alcohol and lacquer thinner didn’t work to remove the tape residue, maybe actual adhesive remover would work but I didn’t have any to try. I went ahead and bent the tabs on the other side just to get a little practice before moving on to the other skin.

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For the second skin I tried using a different tape. I saw on VAF somewhere that someone had good results with carpet tape so I decided to give that a try. The stuff I tried wasn’t going to work because when I clamped everything down the tape squished a little and let things slide around. Unfortunately the tape stuck so well that by the time I managed to get the wood blocks off of it, I bent up the skin really badly. So I have two new trim tab skins on the way.

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After that, I still wanted to make some progress today so I started riveting the other parts of the elevator together. With some help from Meggin, I got the counterbalance rib assemblies together and then riveted the reinforcement plates to the front spars.

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Finished Trim Tab Bends

I finished the bends in the trailing edges of the trim tab skins last night. I followed the recommendation in the plans and built a bending brake out of two pieces of 2″x8″ and a couple door hinges. The only issue I had was that the middle of the brake wanted to bend the skins farther than the ends of the brake. I dealt with this by shifting the skins around in the brake to make sure that the entire length of the skin eventually had a chance to get bent by the middle of the brake. I think they turned out fairly well and according to the instruction manual, the trailing edges can be cleaned up later if they need to be.

Also, I didn’t mention this in my last post about priming all of the elevator parts, but I also primed these skins as well. I figured they would be a lot easier to prime before finishing the bend, and seeing how close the sides come together after finishing the bend, I’m definitely glad they are already primed.

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Elevators primed and ready for assembly

Over the last couple months I’ve been working hard on the elevators. At this point all of the elevator parts and primed and ready for final assembly. We had really nice weather over the weekend so it was a good time to prime but ever since then we’ve had snow and below freezing temperatures, so I’m giving the parts some extra time to cure before I start riveting them together.

I had a couple minor issues when getting the elevator parts assembled and drilled. First, the holes on the counter balance ribs and counter balance skins didn’t really want to line up well. It took some work wiggling the clecos but they eventually got where they needed to be. Then final drilling made everything fit a lost better.

Second was when I was attaching the counter balance assemblies to the rest of the elevators. There are two holes that match up with holes in the spar, that were not lining up either. These holes were about halfway out of alignment and forcing them with clecos wasn’t an option. Van’s suggestion was to match drill the holes, and then since those holes turn out oval shaped, to make a doubler for the flange and add two more holes. Here you can see just how badly out of alignment the two holes were, and then the double with four holes that I added to it on the other side when I drilled the 4 holes:

Everything else went pretty well. The skins have tabs that have to be bent on them to close off the inside of the elevators. I was nervous about messing up this part but they turned out pretty well. You clamp the skin between two pieces of wood where you want the bend to be, and then start the bend with your hands and finish it off with the rivet gun set to a low pressure. I still had to finish off the bend with the rivet gun in this picture, but this is what my setup looked like:

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Got to use my unibit for the first time to enlarge a hole in each of the front spars.

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Prepping and priming everything took about 6 hours. Luckily I had Meggin to help me otherwise it would have taken a lot longer

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And just a couple other pictures showing the elevators cleco’d together:

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I tried to use the recommended setup from Van’s for counter sinking the trailing edge wedges using a drill press, hoping it would turn out better than my rudder wedge, but I still had some problems with one of the wedges. The bit still chattered and made quite a few countersinks that are way too deep, so I ordered a replacement and will try again soon.

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Progress Update – HS & VS finished, working on elevators

I have been meaning to do a couple posts to get caught up on my progress but I just keep getting further and further behind on it, so I’m just going to do one post covering everything. The quick summary is that I’m now finished with the horizontal stabilizer, vertical stabilizer, and have started the elevators.

The first issue I ran into with the horizontal stabilizer was when I riveted the attachment brackets onto the front spar. I gave some of the rivets “smiley’s” while setting them and instead of stopping and figuring out what I was doing wrong I just kept going. So in the end about half of the rivets in each bracket had (what I would consider) fairly bad smiley’s. They looked like this:

 

I got some opinions from Van’s and a couple local builders and 2/3 said I should replace them, so I did. Because these rivets go through about half an inch of parts, I followed a tip I found on VAF that suggested drilling almost all the way through them using a drill bit for the next size smaller rivet. Then insert a punch into that hole in the rivet and punch them out. When I did this, I wasn’t perfectly aligned with the drill so some of the holes got enlarged, and misshapen slightly. Since these brackets are pretty important, I had a tech counselor come take a look at the holes to see if I should replace the parts but he thought they didn’t look too bad. I also emailed Van’s about it a bunch and the person I spoke to also felt that they should be ok. So I put some new rivets in them and once I get the plane flying, I’ll be sure to keep a close eye on them to make sure they are holding up well.

We didn’t have any really big issues with the rest of the HS. Meggin helped me with all of the flush rivets in the skin because I don’t trust myself to use the flush set on the rivet gun and the bucking bar at the same time without putting a dent in the skin. I did have to drill out quite a few rivets because working in the tight space of the inside of the HS cause me to slip with the bucking bar and damage some rivets. Two of the gave me so much trouble that I ended up having to replace them with oops rivets. Here are some pictures from the rest of the HS build:

 

Next, we moved on to riveting the skin onto the vertical stabilizer. I hadn’t done it yet because I was considering running wires through the VS to connect a camera that I would install in the tip of the VS. I couldn’t decide how I wanted to do that so I had been holding off on finished the VS. I finally gave up on that idea and decided that if I want a camera there, I can temporarily attach a camera for the flights I actually want to record.

Some of the rivets on the skin of the VS were hard to do simply because I had to reach my arm all the way into the VS to get to the middle ribs and that made it difficult to see what I was doing. Another section has you peeling part of the skin up so that you can reach the rivets in the front spar. I really didn’t like this part because I couldn’t see what I was doing with the bucking bar at all. I know some people mange to do all of this work by themselves, but I’m glad I had Meggin to help me. Even with help though I managed to slip off of a rivet on the front spar and added a small bucking bar shaped dent to the skin. It’s not too bad so I’m hoping that after it’s painted it won’t even be noticeable at all.

 

So one weekend we got the HS finished and the next weekend we finished the VS. It was a very satisfying week 🙂

Now, I’m working on the elevators. Luckily I already had most of the parts deburred, but it still took me several hours to debur the spars and skins. So far, I have bent the close out tabs on the skins, I have drilled the trim cable routing holes, which was my first time using a unibit, and I have begun clecoing everything together.

 

 

Started riveting horizontal stabilizer

Last night I got started riveting the first parts of the horizontal stabilizer together. I used the pneumatic squeezer for most of it but had to use the rivet gun for some of the rivets. The rivets I did with the gun are not perfect, but I think they turned out fairly good. At the end of the night I had an assembly that looked like this:

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In the weeks before this I spent a lot of time countersinking all of the holes in the spars and stringers and then priming everything. The single flute cutter I ordered worked really well right up until it broke so I switched back to the 3-flute cutter I had been using. A common issue people have with the 3-flute cutter is that it chatters in the hole and creates a bunch of small ridges in the countersink. I found that using my electric drill on the slow speed setting seemed to prevent this from happening, and also helped me avoid having the bit cut sideways through the hole.

I broke up the priming into two sessions. I primed the skins during the first session and everything else on second.  The second session turned out do be my longest priming session to date. Even with Meggin’s help prepping the parts for primer it was close to a 6 hour session. I wasn’t sure we removed all of the residue from etching the parts so we decided to go back and clean everything again so that added a lot of time, plus I was using a new spray gun that I had to learn how to use first.

 

Horizontal Stabilizer ribs dimpled and countersinking trouble

I’ve finished dimpling all of the HS ribs. I started using the 1-inch Scotch-Brite light deburring wheel in a cordless drill to finish off the deburring of the holes in the ribs. Compared to the tools I have been using to debur holes I like this method a lot better. Unless someone tells me this is a terrible idea I think I”ll stick with it.

I also started to countersink the stringers and ran into a couple issues. Some of the holes got countersunk way too far because the countersink cage adjustment came loose without me realizing it. I’ll make sure I tighten it better from now on and will also recheck it regularly while I use it.

The other problem I encountered was the countersink bit cutting it’s way through the part, starting to turn the hole into a line. I think this happened because the part is thin enough that the ends of the cutting parts of the countersink bit extend just far enough down the pilot of the bit to cut into the side of the hole. Here is a picture of the back side of one of the holes I messed up when I was countersinking it.

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I decided to spend some time practicing on scrap parts of the same thickness and found that I’m not very good at stopping the bit from moving sideways through the part. Typically I use a 3-flute countersink bit but I do have one single flute bit from the tools I am borrowing from a friend. I decided to give this one a try to see if I had the same trouble with it, and I was happy to find out that it didn’t seem to want to start cutting sideways at all. Even pushing directly on the side of the tool while it was cutting didn’t cause it to cut sideways through the hole so I ordered one of these in the size I need.

I can still use the 3-flute bits that I have but I’ll need to back up the part with a block of wood or something with a hole for the pilot bit to extend into and clamp it in place so that the bit can’t move sideways at all. Or I could just put it in my drill press.

Horizontal Stabilizer Deburring

I’ve been slowly deburring the holes I final drilled in all of the horizontal stabilizer parts over the last week and a half or so. I haven’t spent too much time working on it because my weekends have been pretty busy and deburring holes is one of my least favorite things to do so it’s been tough to get motivated to do it. Also, I never feel like the tools I have for deburring the holes are very effective. It’s probably user error but for the most part it just seems like the tools push the burrs around without actually removing them. I’ve tried not to worry about it too much since scuffing all of the parts with the Scotch-Brite pad while prepping for priming helps to clean up the holes, but I want to make sure they are deburred properly before I dimple everything. I did some reading on the VAF forums and have decided to dry using some 3M roloc discs in an angle grinder. The blue discs, which are listed as having a fine texture, are what people use and I think they are even less aggressive than the maroon pads I use before priming. If this works the way I’m hoping it will then it should really speed up the deburring process. I’ve got some ordered and will have them later this week so I’ll be able to try them out soon.

I’m also considering using the “light deburring” Scotch-Brite wheels that I recently bought as well. I’ve got a 6-inch wheel in my bench top buffer, and a couple 1-inch wheels for use in my hand held grinder. They are MUCH less aggressive than the other wheels I have been using and do a great job of removing burs without changing the shape of the part. Of course, if I hold the part on the wheel in one spot long enough it will remove a lot of material, but it’s much slower than the “cut & polish” wheel that originally came with my tool kit.