We’re at the point in the practice project where we need to do some back riveting, which is, as one might assume, riveting from the back of the work piece instead of the front.
I had initially bought my back rivet set from Aircraft Tool Supply, where I has bought most of my other tools. What I quickly discovered is that their river set had a small flat set surrounded by a fairly thick sleeve.
At first I didn’t think much of it, but when I went to use it I discovered that it couldn’t fit in the small space between the edge of an angle bar and the rivet hole. The rivet set didn’t even touch the rivet!
So off to the Internet I went looking for a “skinny” back rivet set. Since most didn’t have dimensions provided, I’ve had to eyeball any photos provided. I chose the set by Aircraft Spruce, for $34.95.
I lucked out! The walls of the sleeve on the Spruce one are thinner, and the flat set is wider. Next step…back riveting!
I spent this last weekend down at the local airport and hang out with a friend. It was a great! My friend took me around to a couple hangars, and met Denny, who’s also building a Vans aircraft. His is almost done, so it was inspriational! Here’s a picture of his new panel:
One thing I like about the airport is the social aspect. There’s someone there almost all the time, working on their airplanes or just shooting the sh*t. Pretty cool.
So, I decided to see if there are hangars available, but as it turns out… nothing. At least my name’s on the list for now. I can work on the empennage and wings at home, so I’ve got some time, but I can totally see myself down there with the rest of the hangar crowd.
I’ve been buying more tools lately. Now I have SIX air tools, where I once had 1! Not pictured is a small spray gun I plan to use to prime parts. I’ve also picked up some more clecos (now I have about 30% of the total I need), a double-bend rivet set, a better set of 1/8″ dimple dies (Spring Back this time, not the cheap ones I bought with my squeezer pliers). Oh yeah…some squeezer pliers…
I also picked up a couple 1″ polishing wheels. One of the builders on YouTube was using one, and I thought it was a great idea for deburring smaller work pieces. He also had an angle die grinder, upon which he placed a 2″ deburring wheel, which also looked very handy. So, I went out and bought one of those too.
You spend a lot of time deburring things. You can’t have too many deburring devices!
What else? Hmm.. Oh, yes. I picked up a box of 20 magenta Scotch Brite pads for preparing the Alclad surfaces for priming. Remember how I bought 3 rattle cans of primer? I’m going to try that on this small project and see how it turns out. Chances are very good that it’ll work, but it won’t be feasible to use rattle cans to prime an entire plane without spending as much as a gallon of good spray-on primer (the cans are $8/ea, and the AZCO primer is about $200 for a gallon).
To round off the last 2 rounds of shopping:
Cleco clamps (10 1/2″, 10 1″)
Flush rivet assortment pack
Back rivet plate
More cobalt drill bits
I’ve also improved the “workshop” a bit by buying a second 24″ x 48″ x 78″ 5-shelf metal shelving unit, and a set of 3 LED lights that I put under the existing cabinets I have on the wall, just above my 8′ work table.
The Cleco clamps are pretty cool! they use the same cleco pliers to place, and are just mini metal clamps:
Having survived Practice Kit Part #1, we’ve now moved on to Part #2: the Aerfoil Section! The goal for this kit is to further hone your skills by building a small (12″ wide) aerfoil section, which includes 2 skins, 4 ribs, a spar, and 2 caps.
This one is moving along at a nice clip. We’re at the point where we’re ready to start riveting…well, almost. The ribs on this one needed to be trimmed and rounded, and it looks like we didn’t take off enough material at the trailing edge.
Part of the assembly process includes back-riveting the small ribs to the skins. They must be Mini-Ribs, because my back rivet set won’t “fit” over the rivet…the holes are too close to the bend. I may have to make a small “modification” to the back rivet set and shave off a bit of the sleeve…
Notice how thick the tension sleeve is.
I may just grind a flat side into the Delrin tension sleeve so that it can actually get the flat set onto the rivet.
Tonight the 1/8″ dimple die set arrived, and so we jumped right in and finished dimpling the outside edge of part 1 of the practice project. We tried dimpling a couple with the locking die pliers we bought, and then some with the C-frame dimpler.
The first thing I noticed is that the dies that came with the pliers were definitely not as smooth as the 3/32″ spring backs I bought. After we dimpled the edge, I held it up and man…it looked like the surface of the moon, not the surface of a calm sea at night. You can see the difference, and it is very notceable. Oh well…not much you can be done at this point.
Moving on, I broke out the microstop countersink and tried to get it set to what we thought was a good depth. The wonky dimpling didn’t make it easy to see if we had countersunk deep enough to have the metal lay flat against the angle piece. Looking at it, it didn’t seem deep enough so we went a bit deeper and decided we’d better stop.
Now we starting preparing for riveting, and it’s here that I caught the first major “oops” that we made. When we tried to set the 1/8″ clecos, they would not “grab” at all! In fact, they fell out! Looks like we sunk too deep. :/
So, we had a conundrum to solve. There was no easy way to clamp the two pieces and still be able to rivet. I decided to rivet the 2 outside edges first, after squaring up the pieces. For this I thought it best to give our back rivet set a try. After setting the set into the gun, I discovered that there was not enough room for the set to sit on the shop end of the rivet! the plastic shroud around the back rivet set took up too much room!
Not being able to use that, I decided to switch to a straight mushroom set instead, since I could get that onto the shop end easily. I went ahead and used our new back plate, and stuck a 4-4 rivet in and proceeded to set it. So far, so good… looked like it set fine and even I managed to keep the rivet set on top of the rivet. Good! On to the opposite end! (this was mistake #3 or 4, at this point).
After setting the rivet on the other end, I noticed there was a bit of sag between the work pieces, and without clecos to hold everything in place, it would only get worse! Oh hell…might as well carry on.
The plans had us use 2 AN460AD4-4’s on each end, then 3 AN740AD4-4’s next to them, and then 2 pop rivets in the middle. I imagine that was just to give us a chance to try using different rivets. It was then that I saw that I should not have dimpled and countersunk for the universal OR pop rivets at all. Damn it! In fact, if I had given it some thought at first, and left them as they were, then at least the clecos would have fit fine and held the pieces together better.
Anyhow, long story short, we managed to get all the rivets in just fine, but that edge sure looks ugly!
Ah well… the whole idea of doing these practice projects is to learn here before you start working on the real thing! What are our takeaways for tonight? Universal rivets don’t need countersinking/dimpling. Neither do the pop rivets (at least those that the kit called for). Secondly, countersinking needs to be done VERY CAREFULLY! I inadvertently enlarged the holes on the bottom of the angle bracket, and because of that, clecos didn’t grab, and we had to over-smoosh some of the rivets to make sure they grabbed.
Regardless, we had a lot of fun tonight finishing up the first part of the practice project! Now to order a pair of 1/8″ Spring Back dimple dies, and maybe another practice kit! The Van’s light box looks pretty cool!
And off we go! Today we started the practice project! The final blocker for us going is now resolved…I finally bought a compressor. I’d been waiting on someone I know to get me the specs on theirs, which they wanted to sell. As it turned out, it was a very small compressor, and I knew from what I had been reading that I needed at least a 20-gallon capacity.
What complicated things was as I went out looking for advice on the intarwebs, most people said what I really need was at least a 30-gallon compressor. Those are a bit expensive, so I looked at what I wanted to do, and compared the requirements of the tools I have (and was planning to buy), and I’m fairly confident I can get by with the 20-gallon one.
So, that being decided, I opted for a 20-gallon McGraw from Harbor Freight:
It’s an oil-lubed compressor, which means it should last a bit longer than the “dry” compressors. I also ended up buying an air drill and a touch-up paint sprayer, which I’ll try to use to prime small pieces:
My first…and only…air tools!
So, with everything in place, and the compressor pumped up, Sheila and I tried our hand at drilling, deburring and dimpling! I decided to “cheat” a bit. We had to place 2 rows of 12 rivets along one of the pieces of 0.016″ aluminum. The pieces were not pre-drilled, like everything else in the airplane kit. Being a perfectionist, I was immediately concerned that I wouldn’t be able to produce a nice, clean, straight and perfectly-spaced rivet row. So, I decided to make a template and cut it on our laser cutter first!
After setting up the template, off to the cutter!
Cutting the template on the Glowforge
Once that was done, we just sandwiched together the template, the aluminum panel and the angle bracket and drilled through the template holes. Perfect! Next was deburring the holes and the edges of the work pieces to make sure they were nice and smooth. Then, after dimpling and putting a couple clecos through some holes to hole the pieces together, we pressed our first rivet!
We tried the hand squeezer at first. Several videos have commented that hand squeezing is easier than bucking with a rivet gun, but I found the opposite to be true. I kinda like the gun better! With the squeezer you almost need a third hand (unless you have a table mount you can attach it to). The tricky part for me is holding pressure against the rivet head so that when you start squeezing, it’ll remain flush. I ended up with a “floating” rivet, where I squeezed and left the flush head almost 1mm above the aluminum (I came back later with the rivet gun and managed to rat-a-tat it back level).
ATS Pro 3X gun
We both practiced drilling, deburring and riveting the first part of the first practice project. I neglected to order 1/8″ dimple dies for the second set of rivet holes in this practice part, so we’re waiting for them to arrive so we can attach the last piece, which will also require countersinking!
I’m really impressed with the result, though. Not bad for our first-ever time doing any of this at all! I think if we’re careful, take our time and folliow the instructions carefully, we will absolutely be able to put together an airplane by ourselves!
I’m planning on building at least the empennage kit in my garage, but am finding that I need to go on a cleaning spree if I ever hope to have the room.
I’ve already started cleaning off the 8’ block-top work table I have in the back portion of the garage where I plan to do most the assembly, however I will also need another flat surface that I can easily move all the way around.
At first I considered building one or two of the work tables that EAA 1000 published plans for, but they’d be bulky and heavy.
So instead I decided to buy a Bora Centipede, which has an expandable 2’x4’ frame. I also bought a 2’x4’ pressboard sheet that I should just be able to pop atop the frame. This’d make for an easily stored work space.
The Centipede arrived a couple days ago and it looks like it’ll work great, especially since it has a 2500 pound capacity.
Okay, so now that I received the bulk of the tools I need to start the practice project, I need to decide on what kind of air compressor to buy! The air compressor is really only going to be used for setting rivets, since the rivet gun is pneumatic. I could go buy a bunch of other air tools as well, but then I need to make sure the compressor I buy would support them all.
There are 2 standard types of air compressors: oiled and oil-free. This refers to the way that the engine’s piston is lubricated. In oil-free pumps, there is a Teflon (or similar) coating on the cylinder walls that serves as lubrication for the piston. In oil rigs, you add oil, which is the primary lubrication.
From what I’ve discerned, the oil-free compressors are cheaper, but maybe a bit louder. They also don’t last as long. I mean, we all have that one non-stick Teflon pan in the kitchen that has slowly been losing it’s nice slippery surface. After a while everything sticks to it. Since you can’t renew that lining, at some point the pump is going to fail.
The oil-based compressors are the opposite. They’re more expensive, a little less noisy, and last longer. The downside is that you have to change the oil every once in a while. This isn’t really a downside to me…maybe it is to people who can’t be troubled with a little extra work.
I found a couple compressors, 2 at Harbor Freight and 2 at Home Depot, that look interesting. They’re both 20-gallon compressors, and a mix of oil and oil-free. Prices range from $149 to $300 for the one’s I’m checking out.
As a sanity check I posited on the Facebook RV-7 Builder’s page whether people thought my leading choice (a 20-gallon, 1.6HP, 135PSI oil model) would be sufficient. The response was that for riveting and squeezing it’d work, but don’t even think about drilling or grinding! That’d require at least a SIXTY gallon tank and 3HP! After a quick check, the price for that could be up to $1,200!
I think I’ll stick with my trusty electric tools for drilling and grinding.
After an unexpected break from the project, I’ve returned home and found all the tools I’ve ordered have been delivered! Exciting!
Since I went over them in previous posts, I won’t expound too much on what I got. EVerything arrived, so I’m all set for the practice project….with the exception of one thing…an air compressor.
I have a small compressor I’ve used for setting brads into the fenceline, but I need something bigger to run the rivet gun, and any other air tools I plan on using. I’ve had my eye on a couple 21-gallon compressors…one from Harbor Freight and one from Home Depot. Neither place had the one I wanted in stock, so looks like I’m going to just order online. I saw an 8-gallon Macgraw compressor at HF, but it’s only $10 cheaper than the 21-gallon. So, if I can still get the price for the 21-gallon ($149), that’ll be the one.
There are a bunch of decisions that have to be made when you start an airplane-building project, other than what it is you’re going to build. Things like where to build it? What timeline do you want to try to follow? how to get or buy tools? These are some of them.
Another one, which evidently plays on the minds of many builders, is whether or not to primer the metal on the inside of the airplane. It seems like it’s quite a contentious issue! Some builders insist that it’s not required. The Alclad aluminum used in the plane should keep corrosion out. Still, others insist that without internal priming, the plane won’t last 5 years. It’s difficult to figure out just which side of the fence to land on.
Beyond the initial question lies a series of equally important ones. If I do decide to prime the metal, what should I use? Which brand? Should I use a time-honored zinc chromate primer, with all it’s health issues, or instead use the virtually harmless zinc phosphate primers instead, while possibly sacrificing some of the protective properties? How much weight will this add? How much time?
Once that’s sorted, yet others remain! How am I going to apply the primer? Depending on who you ask, you’ll be told that you must use a high-quality spray gun from Devilbliss, or, you’ll do fine with a cheap $60 gun from Harbor Freight. Should I get a spray gun with a 1.3mm or 1.4mm nozzle? Do I need a new compressor? Can’t I just use a rattle can primer? Craziness!
Well, you can’t let this hold you back, so we talked about it and made a decision. I found that there are rattle cans of zinc phosphate primer, and there is some good feedback on them. So we’re going to order 3 cans and use it on the learning project to see how it turns out. This way I don’t have to invest in a spray gun at all (although I do have to buy a bigger compressor than the one I have now). The way I see it, not using the gun is fine on the internal parts. As long as we can get good coverage, I’m happy. I don’t care if it’s messy on the inside.
This’ll change if decide…to paint the plane ourselves… Just kidding!
I got three cans from Skygeek, for $8.03 each. And it’s green, of course!
