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I've been studying solid rivets but their only good for about 200 lbs. in shear (1/8" dia., AN 426 AD, 2117-T4).
Solid rivets have to be soft enough to drive but that leaves them somewhat weak. Pull type rivets like the Avdel CCCQ Series are actually stronger at around 300 lbs. with all the safety factors. Flat head #8 H.S. screws will get you over 1000 lbs. in shear, but now your base material strength will control.

Hello Gents.

John and Lonnie-S

For sure. it may take some time to put together but I will cover what easily available to the locost building community. There's no sense going over obsolete or highly specialized fasteners only available to OEM's or MRO's Facilities.




Good points. Keep in mind that rivets are sized and installed in numbers to match material strength in its specific application. For my upper sidepod supports, their structural load is not primary (pressure, ground, or aero). In fact the majority of the aluminum on the car is just to panel it for closeouts while inheriting its benefit of rigidity. Its really not that important for my application. However I did treat it as it were a primary structure in the way it was designed, prepped and installed. Note I could have used -6 MS rivets, they were not available from my suppliers, who have since closed up, and I did not have the proper pulling head, so -5 it was. For my applications, light, rigid, and robust are the objectives.

Other points to note about the benefits of blind vs the other fasteners you mention is the fact that solids expand radially during installation forming a much tighter and more durable install which is more resistant to loosening. Also AD rivets once driven work harden during install and become MUCH harder when they're worked. A and B rivets are much softer and are designed to be used with different alloys. The other solids D, DD, and E are specialized for manufacturing and have there place, they are much stronger. I have no experience with these other than school.

The exception to radially expanding blind rivets is the (wiredraw) Cherrylock and CherrymaxAB, or any other NAS1398/9 rivet. These fill holes and are typically installed in fluid tight applications. they lack the clamp up force of the M7885 (cherrymMax) or NAS1738/9 double action locked spindle rivet. Im going from memory here, I may have these numbers backwards btw. I spent a lot of my time in the shop replacing fasteners in flight controls that had begun to show signs of failing. Ever heard of the term "smoking rivet"?. Basically the rivet is not longer tight, it rattles around in the hole, the base material and the rivet begin to corrode and leave a trail of black/grey oxidized aluminum behind it. Next time look for it when you ride on a plane. You may see no fasteners in the flight controls if they're composite and buried under layers of sealant, filler and paint. But have a look anyways. That's the first sign of the joint failing. The good news is that these things are over built and typically have many more taking the load (than required) and were bonded with a 2K poly-sulfide. The shear strength is not of paramount importance when you consider the vibration loads and other factors that the joint is exposed to. That is the benefit of solid rivets.

Back to the flight controls. Id have the opportunity to replace fasteners when a plane was due in for check over a few days. Without fail, Id find nominal size cherry max rivets in obviously oversize holes. Keep in mind some of these planes were 30+ years old and in excellent shape structurally but someone did not take the time to check hole dimensions with the original repair. Simple process to get them out, and once out, oversize the hole (which was never done after the original rivet failed) and reinstall an oversize cherrymax wet with sealant. This would typically get the joint many more years of mileage until the flight control needed to be re skinned and maybe new ribs. These planes I worked on flew from gravel strips, and rock damage thrown up from tires was prevalent. Ive seen a lot of misuse and poor installation of blind fasteners, just because they're easy to install or have higher shear ratings, does not mean they are better by any stretch. Knowing this, I do my best to make sure the joint is designed as best I can (budget, tooling, and abilities limiting) and give the parts the best chance of survival knowing the weak link is the blind rivet no matter what the loading.

Otherwise That CCCQ rivet is a 120 degree countersunk stainless/stainless rivet, hard to compare to a AN426AD as it application are different. To keep it simple if you were using Stainless for primary structural application, you'd want a compatible fastener, so you'd look for a steel, stainless, monel or inconel fastener for corrosion resistance, or to be correct, the manufacturer would tell you what to replace it with. Typically stainless is not typically primary structural material in aircraft construction, unless there is a high heat application, then it is appropriate. If you chosen Stainless for a primary structure without the need for it (i.e. firewall), then your going to incur an unnecessary weight penalty.

Try not to over think it. If you want to build primary structure from aluminum alloys, don't look at general aviation unpressurized aircraft fuselages or flight controls. Look at wheel wheels, gear bays, engine mounts, bulkheads, integral fuel tanks etc. Ive done a lot of walk-rounds on aircraft and had my head in wheel well LOTS and that's were you get an idea of how the engineer's get the most of aluminum in primary structure. Perhaps have a good look through some of the Van's RV kit plane build logs and you'll see hows these things make best use of the material (for the budget). The RV series is the best designed kit plane in IMHO.


Andrew

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build log http://locostusa.com/forums/viewtopic.php?t=2142

Just a quick insert here.

I bought a few hundred rivets: Round head. 1/4 inch long or shorter (can't remember), about 1/8 in diameter. These were to fasten an aluminum skin to some light frames I had made. As it turned out, they went in really easily, filled the space tightly, and held the parts together very well. Use a drill size that leaves a little room for sliding the piece in, and the setting will crimp it tight.

It just took some care in making sure the space was tight when they were inserted; in other words one could make a loose connection if one weren't careful, but it wasn't hard to do. Just use a firm backing board to make sure it is tight. I used a light ball-peen hammer to set them and it worked fine.

I have been converted to a rivet-man overnight! Also the parts are cheap so you have little risk.

Good stuff. Ball peen hammer and a block of steel is about as locost as you can go, the end result is the same, solid and permanent fastening system.

Recent progress included installing nut plates in the lower side pods to secure the lower part of the upper side pods.. Confusing? 3 AN-3 bolts in the bottom that you cant see from the outside and 3 AN-3 bolts you can see. They are bolted in for now to help with some alignment work with the other two body pieces. This is as good as it going to get short of filler and shims which I knew would be required in a few places. I did start to fill some pin holes and laminating screw ups with epoxy fairing compound in the body work pieces. I had some leftover so it was used for a few low spots on the headlight lens form. There is LOTS of filling and sanding to do!! I think I might tackle this when it starts to warm up around here.

Other recent work is the headlight lens thermo-forming project. The female mold will sit on a wooden box that act as a negative pressure chamber. The plastic will be heated in an oven until its sags, then removed and placed on the forming mold. Vacuum pressure will then be applied to a port on the box and the heated plastic will be drawn into the mold via a dozen or so small holes. Somewhat difficult to explain, I intend on making a video during this process.

Regarding the form. It was mounted on the same size MDF board as the vacuum forming box. Once the mold is done, it will be secured right on the box. The dimensions of the tooling surface are the maximum my oven will allow. The oven is the bottle neck for this sub-project.

Anyways, I noted that I used epoxy fairing compound to fill a few low spots on the lens form as I had some mixed up. Well this turn out to be a demonstration of why that is not a good Idea. I know better, just some oversight on my part.. Here's why.

Epoxies and Polyesters get from liquid to solid state in different ways. Polyesters polymerize and epoxies cross link. MEKP is added to polyester resin, this catalyst dissolves another chemical that's keeping it in liquid state. Where as epoxies A and B parts are added together an each contribute to end result, a solid. Epoxies can be derived from many families of chemicals. Specifically in my situation Bisphenol Amines and Cyclo-aliphatics. Amine resins tend to blush leaving a waxing film on the surface when cured, cyclo-aliphatics do not. This fairing compound is Bis phenol Amine.

Knowing this, the guidance is that you should not apply a polyester over an epoxy. The reason is that the un-reacted amines present in the epoxy from improper mixing WILL inhibit the function of MEKP catalyst in the polyesters. The fairing compound hardened like I expected, but at the chemical level, a surplus of Amines exist on the surface. For myself, the end result was uncured polyester surfacing primer on my lens form. I know the theory, this is the first time Ive actually seen it. Moral of the story, know the compatibility of your chemicals.

It was scrapped off and cleaned properly . I'll be ordering more surfacing primer in short time too as I'm out. It seems like whenever I do composite work, I always need a gallon of something really expensive..

However I did save a whole bunch of money by not buying that 2K expanding urethane foam kit and making due with what I have. I needed to fill the gaps in the air intake form. I was planning urethane foam, carving it down and applying filler right over top as I did with the body work forms. Nothing wrong with this method but I've realized most of the filler ends up on the floor as dust and it takes many applications to build up shape with filler. Maybe I wasn't using the best filler for the job. Anyways, I mixed my own tar-like consistency of polyester resin, polyethylene fibers, and black pigment to see the shape better. I'm sold on this now. Its highly trowel-able with a much longer work time that filler(bondo). And once cured, its much harder and takes very well to grinding as as opposed to sanding. Filler has its place, but for the initial step, this is the bee's knees!

As far as mold making goes. I'm going to put that off until the weather warms up and there is no longer a 3 foot wall of snow and Ice outside the garage door. This allows better cure times while airing the place out with the garage door open. I will have three molds to do, the headlight lens mold, air intake mold and the radiator duct mold. I haven't talked about the latter much but its a simple part that I can build the mold without making a form.

Anyways, here's some pics

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build log http://locostusa.com/forums/viewtopic.php?t=2142

Continued excellent work, as always, Andrew.

Vacuum forming certainly lives up to the adage of "99% preparation" with the actual forming happening very quickly.

It's been a long time since I've done any but I seem to remember putting a heat lamp on the form to reduce the possibility of thermal stress and increase the odds of the piece fully forming.

Good luck with it, it'll be interesting to see the photos.

Ron

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They say a journey of a thousand miles begins with a single step. By the time you finish the car it'll feel like you've done it on your knees.

Forgot how much I loved following your build, Andrew.
Beautiful work as always, buddy!

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Moti

My R1 powered Locost build log

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just spent the last 2 days reading through your build, and I gotta say wow that is some insane level of workmanship. very impressive. Is doing stressed skin really that simple? just rivet the aluminum paneling into the frame? or did i miss some small detail?

Still alive with good reasons not to post. Thanks for the comments guys.. I walk by my project multiple times a day and think about it more.

Long story short, haven't touched the car since my last post, but November through March next year expect some progress for those following my 10+ year build.

... the story goes like... wife gets herself knocked up again in march followed by a nightmare pregnancy were she was on bedrest for the last 4 months which we were going to the hospital every week checking for a heartbeat.. no fun. My lawn and tree service business grew alot during that period which I worked as much as I could as well as flying full time. Days started at 5am, getting the dog walked gear loaded and getting my daughter to daycare while my wife rested.

Our second girl was born in November of 2015 and perfectly healthy depsite the scares. I managed to sneak in some work on the car prior to the turf season. Business grew again, and I was jammed up for time making sure I was available to parent, fly, and take care of the half million square ft of turf I'm managing... Then I broke my arm in June of this year, not at work, but on a weekend family get away falling backwards from a rock! I'm almost ready to get to my regular job, my wife also goes back to work in November, the kids go to daycare and I will have the house to myself a few days of the week to get some car time!! So life really happened in the last year and half. The good news is that I took a forced break from my business, flying, and had some precious time with the kids that I would not have taken being highly motivated by the mighty dollar!


... On to car related stuff.

I had a member ask me about metal bonding long ago, I decided to post the answer here so everyone could see.

"Being as you are the go to guy for aircrafty questions here goes. You talk about bonding / riveting aluminum to steel but after trolling your posts I haven't found any details about doing it. What alloys are you using? What joint pretreatment is required? What adhesive do you use and where do you get it?

I really enjoy reading your posts but I haven't found this information. If you have posted this stuff please give me a hint as to page.

And thanks for posting."

I think there a few other aircraft people here as well, but to answer this question, I actually have no metal bonding as a sole and primary means of attachment. The rivets serve as the attachment and the 2K polysulfide is a sealant with bonding properties... for metal to metal adhesive bonds,

1)the joint is only as strong as the weakest link. you can have the strongest adhesive, but the weakest link will give first. In my application, the adhesive sealant is bonded to the primers on the metal, in which case the prep was abrasion for steel, followed by wipe dry with acetone, followed by IPA, sprayed with a 2K epoxy industrial coating.

The aluminum was prepped with phosphoric acid and abraded wet with maroon scothcbrite, rinses, and chromic acid converted. this was air dried, cleaned with acetone and IPA, then spray with PPG super koropon primer.. this has a very good bond to metal. So basically the weakest link here is the aluminum's bond to the primer. If you peeled up any of the panels on my chassis, im sure the aluminum primer would peel up with the sealant.

Now, I know some people will want to do experiments and demonstrate that mechanical abrasion followed by and advanced adhesive bond when cured will be the strong suit in a joint... immediately after the cure ONLY. The invisible corrosion that happens underneath primers and coatings is what will degrade the bond in a aluminum metal to metal bond and hence I do not recommend anyone here relies on it for primary structure. How long will it last, I do not know, 1, 2 3 years... its a guess at best.

So how is it reliably achieved? It is achievable under the right conditions and chemistries. Metal bonding in aerospace is achieve by PAA, phosphoric acid anodize. Raw materials are anodized, which deposits a hard layer of aluminum oxide on the surface, this is porous. Within a window, a primer is applied and adhesive film bond can then take place. this process is done at the manuacturing level is tightly controlled. They build it to 150%, so you can repair it to 100%. repair materials are available on the market, sol-gel, AC-130 come to mind and details are laid out in SRMs, Structural repair manuals.

knowing all this, I know that I wouldn't attempt it, as rivets and sealant is common, easy, and locost.

here's a reference for review.
http://www.pfonline.com/articles/anodiz ... -aerospace

Cheers
Andrew

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build log http://locostusa.com/forums/viewtopic.php?t=2142

Much congratulations on being so successful with life getting in the way! "life is what happens while you're making plans", it's the best.

Also thanks for your writeups, I just now read the material above about rivets etc., it is very useful.

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
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Glad to hear you posting again! I was a little concerned about losing a prime source for air frame construction. That stuff can be a little opaque to the average car guy.

I know what you mean about life. Congratulation on the successful offspring. For myself things have taken an unhappy turn. While doing a little yard work I managed a 15' fall from a tree (really dumb) and concussed myself and screwed up my good knee. Things are mending and I am eager to do a little aluminum to steel bonding.

I don't know about the rest of y'all, but if Airframe wouldn't attempt it, I ain't even gonna think about it in front of witnesses...

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

Agreed. I've worked in the business for almost 20 years, metal bonding is a nightmare. Even with all of the correct chemicals, equipment, and stringent processes, relying on a metal (aluminum, steel, stainless, titanium, etc.) bonded joint without chicken rivets is just asking for trouble. Now if you'd like to attempt it there are lots of good processes that can be utilized the "garage environment" to make a robust bond. Another important thing is make sure you also read up on the actual bonded joint design...........shear is your friend, tension/peel are your enemies. Good luck.

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My build http://www.locostusa.com/forums/viewtopic.php?f=35&t=7370

Andrew, glad to see your update and I'm glad to hear your second child was born healthy. Nice to hear that your side business has turned out so successfully.

I know you're normally a busy guy but I was starting to wonder how things were going. 10+ years, amazing, how time flies.

Hope you get the anticipated time to work on the car.

Ron

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They say a journey of a thousand miles begins with a single step. By the time you finish the car it'll feel like you've done it on your knees.

Andrew- As a follow up to my smart-a$$ post upstream, let me say first of all that I'm glad the new baby was born healthy. That's a very good bit of news. Sorry your wife and you had to go through so much to get her here, but I'm bettin' you think it was all worth it now. Good on you and her for doing all the right things. Got pictures? Does she have an Uncle Bubba? I can arrange one for her, if you'd like...

Then there's the arm. Geeze, talk about bad luck! Hope that is all healed up now, 'cause you gotta have a steady hand on the yoke, Bro... Again, I'm bettin' you do...

Thanks for the update. I hope we get to share more of your build soon.

JDK

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

lolz, I've done metal-to-metal bonding successfully, on body mounts...

...for scratch-built slot cars, brass-to-brass, using JB weld.



works pretty mint for that. don't think I'd care to try that on something I'd be sitting in and driving though.

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The B-3 build log: http://www.locostusa.com/forums/viewtopic.php?f=36&t=13941 unfortunately, all the pictures were lost in the massive server crash

The beginnings of the Jag Special,
https://www.locostusa.com/forums/viewtopic.php?f=36&t=19012
Again, all pictures were lost.