Building teardrop structure out of aluminum with Rivets???

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Re: Building teardrop structure out of aluminum with Rivets?

Postby MeelisV » Wed Aug 21, 2013 1:07 am

alaska teardrop wrote:
    This is a good thread to further the discussion of designing & building with aluminum. :designing:
    Meelis, I followed your build thread from the start and am thoroughly impressed with your plan & execution. I wish there was more discussion on constructing with aluminum.
    Having some past experience with welding aluminum, I can say that your welder must have experience, talent, patience & precise welding equipment to weld all four sides of tubing that is that thin (2mm). Note that in the Livin'/Camp Lite video (min. 2:35) that they do not.
    Can you tell us the thickness of your exterior aluminum?
    :peace: Fred


tubing is 20x20x2 mm (0,79 " x0,79 " x0,079 ")
and "skin" is 1mm (0.039 ") anodized aluminium

i´m not big story telling in english but you can ask and i will answer
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Anything a man says after that is the beginning of a new argument.
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Re: Building teardrop structure out of aluminum with Rivets?

Postby jonesnforcampin » Sun Sep 08, 2013 9:28 pm

RandyG wrote:There are many to choose from, and it's hard for me to say what type to use because they are called different things for people. A pull-through is a pop rivet, not for structural use.
A cherry-max, which was discussed above, is just as strong as a solid rivet but is shot with a special gun, which can be expensive. Think of a super pop rivet.
Jo-bolts are another blind fastener and you can shoot them with a drill and a wrench. They are just as strong as a nut and bolt. For the cost of jo-bolts, I would just use them in critical points.
Those are the two I would consider, cherry max are cheaper, jo bolts stronger. Do a search on both, they may come up as a different name.


Ok, I must have some weak Google-fu because I am having a tough time finding the Jo-Bolts. Is there a different name that I am not finding?

Also, does anyone have the product name or number for that tape that was referred to that is used to tape AL to AL?
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Re: Building teardrop structure out of aluminum with Rivets?

Postby alaska teardrop » Mon Sep 09, 2013 9:22 am

    Image
    Image
    The tape, that at least I referenced, is 3M-VHB4919F.
Northern Lite Traveler design: viewtopic.php?f=27&t=51991
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Re: Building teardrop structure out of aluminum with Rivets?

Postby alaska teardrop » Mon Sep 09, 2013 10:05 am

RandyG wrote:The skin on the bottom of my frame made it very rigid, so skin adds alot of strength to any structure. A steel frame would be easier, less engineering and cheaper because you would use less material to make it strong enough. But it would still be heavier. But, Randy, can you point us to a proven reliable 'engineered' formula & numbers to back up your statements? The weight in the walls and roof could make it top heavy. Then how would you attach aluminum skin to the steel skeleton? Although the discussion in this thread is about building an aluminum cabin, many steel skeleton trailers/rv's have been built over the years without a 'top heavy' condition. I've built five of them using rivets to attach the aluminum skin to the steel tube framing. Fred
Northern Lite Traveler design: viewtopic.php?f=27&t=51991
Minimalist torsion axle frame: viewtopic.php?f=35&t=12220
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Re: Building teardrop structure out of aluminum with Rivets?

Postby RandyG » Mon Sep 09, 2013 11:28 am

Proof to back up my statement? Aluminum has a better strength to weight ratio than steel, thats why planes are made with it. I'm sure you can make a cabin from steel and keep the weight to a minimum but I think Al would be a better choice. What did you do to protect the Al from corr. on your builds? What kind of rivets did you use?
Before I became a metal worker, I always thought of aluminum as an inferior metal. But now, I see other people selling it short but I know it can be used for almost anything steel is used for and some times be the better choice. Thats one reason I built my frame the way I did. It may have been easier to barrow a welder and build the frame in a matter of weeks or days but I liked the challenge of engineering something that hasn't been done (as far as I know).
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Re: Building teardrop structure out of aluminum with Rivets?

Postby doris s. » Mon Sep 09, 2013 11:58 am

JohnSw wrote:In the world of big trailers.. I used to own a 5th wheel.. there are 3 basic types of wall framing. There is wood (not so much anymore) and 2 types of aluminum frames. One is welded aluminum tubing the other is aluminum tubing that is glued and screwed.

The glued and screwed construction uses aluminum tubing with aluminum angle pieces at the joints. These angle pieces are held in place with glue (probably epoxy) and a screw through each leg. Sunnybrook and Cedar Creek are two manufacturers that uses this method of construction. I looked for a picture to illustrate but didn't see a good one in their literature.

At the time, the idea of a steel screw holding aluminum parts together did not appeal to me due to the potential for galvanic corrosion so I bought a Cardinal with a welded aluminum wall construction. After owning it for a number of years, reading forums and talking to other owners, I decided that it really didn't matter what type of wall construction a unit had. They were all cheap but they also all went down the road without the walls falling apart.

You already possess the skill and tools to build a glued and screwed frame....

My husband and I just bought an aluminum truck cap and we were thinking that a tear made with that kind of construction would be fantastic, however we don't have welding experience. John, do you think an aluminum frame that is all glued and screwed would be strong enough? We want to build a large tear drop standy. This would be a great way to frame if it is strong enough.

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Re: Building teardrop structure out of aluminum with Rivets?

Postby doris s. » Mon Sep 09, 2013 12:01 pm

My husband and I just bought an aluminum truck cap and we were thinking that a tear made with that kind of construction would be fantastic, however we don't have welding experience. John, do you think an aluminum frame that is all glued and screwed would be strong enough? We want to build a large tear drop standy. This would be a great way to frame if it is strong enough.

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Re: Building teardrop structure out of aluminum with Rivets?

Postby alaska teardrop » Mon Sep 09, 2013 4:50 pm

RandyG wrote:Proof to back up my statement? Randy, I don't mean to get in an argument. This forum is about exchanging knowledge as we see it. Because you are an experienced aluminum fabricator & mentioned your aluminum chassis I asked in all sincerity, for the benefits of Jonathan, myself and others who might be considering an aluminum chassis. Primarily a tongue/chassis design made with aluminum that lives up to a recognised standard. i.e. a trailer chassis design made with aluminum that would go down all different kinds of roads for let's say 100,000 miles without stress fatigue. Aluminum has a better strength to weight ratio than steel, thats why planes are made with it.. I agree. When comparing the vertical section modulas for steel vs. aluminum tubing, they are relitively the same, yet the aluminum is about 1/3rd the weight. But what do you do about the fact that aluminum fails after fewer cycles (driving down the road) then steel? Triple the depth? I've poked around for a formula without luck & was hoping that you could supply it. I'm sure you can make a cabin from steel and keep the weight to a minimum but I think Al would be a better choice. . Well, that may depend on the intended use of the trailer, but off topic, since Jonathan has already decided on an all aluminum cabin. viewtopic.php?f=2&t=57200 BTW, the trailer pictured below right does have an all aluminum cabin on a steel chassis. What did you do to protect the Al from corr. on your builds? What kind of rivets did you use?. To answer that question, I'll quote myself from another thread:
Thanks. Good question. No, I don't expect galvanic corrosion in this trailer to be an issue at all. Strength & durability are two of the reasons to build this way.Here is a Anodic index: http://www.engineersedge.com/galvanic_capatability.htm Steel has a value of .85v. The aluminum used in this trailer has a value of either .90v or .95v for a total difference of .10v. That's below the acceptable difference of .15v for outdoor use.To prevent moisture intrusion the steel tubes for the cabin floor are welded closed. The entire steel chassis is sand blasted, acid dipped & powder coated. The VHB tape not only acts as an adhesive & seal but separates the aluminum from the powder coated steel. The only direct contact between the metals are the rivets. The rivets are 3/16" closed end aluminum structural rivets. Closed end rivets won't leak through the center. They make an exceptionally strong seal to close off the rivet hole. 840# tensile strength. About the same as a #10 plated machine screw & more than a stainless steel screw. In addition, the interior cabin has a complete vapor barrier to prevent interior moisture from entering the wall, ceiling & floor.
Sometimes I think people make an issue about galvanic corrosion because they're relating to metal boats on salt water, which are a sort of floating battery. The other would be continuous driving on salted winter roads without a regular washing. Either of which is managable by not towing on salt water and/or washing. And, think of all the examples on cars & trucks where steel & aluminum meet without galvanic corrosion issues for years. The eight year old aluminum over steel trailer below left has seen a variety of weather & has no signs of galvanic corrosion & I don't expect it will untill we're long gone. :)
Before I became a metal worker, I always thought of aluminum as an inferior metal. But now, I see other people selling it short but I know it can be used for almost anything steel is used for and some times be the better choice. There ya go. I have visions of an all aluminum formed sheet & riveted monocoque including the tongue. No extruded skeleton structure at all. Like the tub of a race car. Thats one reason I built my frame the way I did. It may have been easier to barrow a welder and build the frame in a matter of weeks or days but I liked the challenge of engineering something that hasn't been done (as far as I know).
    :peace: Fred
Northern Lite Traveler design: viewtopic.php?f=27&t=51991
Minimalist torsion axle frame: viewtopic.php?f=35&t=12220
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Re: Building teardrop structure out of aluminum with Rivets?

Postby RandyG » Mon Sep 09, 2013 7:17 pm

Sorry Fred, I read that as an argument (lost in textlation?). No hard feeling. I'm not used to people actually wanting to get into the molecular structure of metal. Al vs steel, al has a very harsh grain to it, much like wood. Steel's grain is almost not there, but it does have some, too hard to see. Al will most likely crack with the grain so you have to bend against the grain, opposite of wood. So with square tubing, the grain is running length wise so the corners are going with the grain, there's fault. If I were to make an al cabin, I would do it with hat-channel or angle bent against the grain.
Corrosion is going to happen no matter what you do, all you can do is slow it down. I think you're right, that shouldn't corrode for years and years.
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Re: Building teardrop structure out of aluminum with Rivets?

Postby JohnSw » Wed Sep 11, 2013 9:59 pm

doris s. wrote:My husband and I just bought an aluminum truck cap and we were thinking that a tear made with that kind of construction would be fantastic, however we don't have welding experience. John, do you think an aluminum frame that is all glued and screwed would be strong enough? We want to build a large tear drop standy. This would be a great way to frame if it is strong enough.

Doris


Yes, I think you could build a glued and screwed frame that was strong enough. Obviously it would have to have an adequate number of framing members. ( we are talking about the body of the trailer and not the actual trailer frame )

Just because something is possible doesn't necessarily mean that one ought to do it. If I remember correctly when we were buying our 5th wheel, wood construction was heavier than aluminum but by under a 1000# on a 12000# trailer. I looked online and 6061-T6 1" X 1" tubing with a .065" wall weighs 0.28#/ft. Poplar has an average density of 29#/cubic foot. Therefore, a 12" long poplar 1x2 weighs 0.227#/ft .

I know this isn't a definitive argument for wood over aluminum but cost and the ease of working with wood have to be considered.
John
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Re: Building teardrop structure out of aluminum with Rivets?

Postby Ron Dickey » Thu Sep 12, 2013 12:54 am

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Re: Building teardrop structure out of aluminum with Rivets?

Postby Jiminsav » Wed Sep 09, 2015 9:53 pm

anyone know where to get a HS310 rivet shaver cheap?..used?..all i see is $250 bucks new..and can't afford that for one weeks use. :worship:
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Re: Building teardrop structure out of aluminum with Rivets?

Postby elcam84 » Sat Apr 14, 2018 8:07 pm

Jiminsav wrote:anyone know where to get a HS310 rivet shaver cheap?..used?..all i see is $250 bucks new..and can't afford that for one weeks use. :worship:
I know old post but been digging around at the aluminum builds. Working at designing a riveted teardrop in my head before committing it to paper...

Anyway if you need a rivet shaver you can do the poor folk way and use a countersink with a rivet shaver cutter. The cutters run around $30 or so. It's the only rivet shaver I have until I find one at an estate sale. Lots of old GD,Lockheed and contain tools and materials at estate sales from time to time but it's getting harder to find.

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