Teardrops n Tiny Travel Trailers

I'm having a bit of difficulty sourcing the aluminum for the outside skin of my TD. I live in a rural area that doesn't leave me many options.

I was able to find a place (not very close, but in the same state) that sells the aluminum for truck trailer roofs. I've seen posts in these forums from people that have suggested using this type of aluminum, possibly they have used it too.

Anyway, the guy on the phone was clueless regarding the grade and temper of the aluminum they sell, only that it was .040" thick, 'shiny', and $9.50 per linear foot.

I am guessing, through some Google research, that it is most likely 3003H16 mill finish aluminum. I had been hoping to find 5052H32. I did more Google research to determine what the difference is in the alloy and temper, but I still have some reservations. I was hoping to take advantage of the collective knowledge/experience of the group to help me sort this out.

Is there any real discernible difference between the 5052H32 and the 3003H16? Is there any reason that I should NOT use the 3003H16 truck trailer roofing? If not, why was I recommended to buy the 5052H32?

That's all Greek to me. I used .040 aluminum on my roof and it worked great. It seems that .040 is the common thickness used here.

Ispent 36 years working aluminum at Boeing.

1st 4 digits indicate composition.

H is for strain hardened; (1) hardened only (2) Hardened and paartially annealed (3) Hardened and stabilized (4) Hardened and laquered/painted

2nd digit indicates level of hardening based on minumum tensile strength

Unles you are planning extreme forming; the H16 would work fine as a skin

And that's about 4$ a running foot less than we are paying on the left coast! Doug

Ageless

Unless you are planning extreme forming; the H16 would work fine as a skin

Indeed. Another thing to consider is that if the stuff is good enough to cover a truck trailer roof, it's gotta be good enough to cover a teardrop.

Perhaps the reason you were recommended a slightly higher grade aluminum sheet is the "gourmet" quality of said sheet. There's always a "perfect" material to use in any given situation, but oft times it may border on overkill.

Now I'm one of the first people you'd talk to that would recommend overkill; I like it... but I can also fine tune something straight into the ground when presented the opportunity.



Think about the real reason for using aluminum, or any covering for the plywood that our teardrops are made with; it is to shield the plywood from direct sun and water, two destroyers of wood. Some early teadrops used "leatherette", or, vinyl as the wood covering.

somebody correct me if im wrong...but 5000 series aluminum is marine grade....not needed for a trailer roof...

laoutdoorsman wrote:somebody correct me if im wrong...but 5000 series aluminum is marine grade....not needed for a trailer roof...

I’d be happy to. The series 1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, and 7xxx, have nothing to do whether or not the alloy is suitable for any given application such as ‘marine’, ‘outdoor’, etc., but rather refers the alloy family. Within that family the various other sub alloys and heat treats vary the properties of strength, workability, corrosion resistance etc. Even among a single family the corrosion resistance, for instance, could vary dramatically.

The 3XXX alloys are not so structural, but form easily (if I remember correctly – they don’t even show up in the Mil-handbook, so we don’t use them for ‘structural’ applications, and by that I mean a primary load carrying member. The 5XXX series has better strength properties, and can generally be bought in one of your larger cities. It is considered a low-grade structural material. It used structurally in home-built cars etc.

Having said that, you aren’t using the aluminum as a structural alloy (the top of the truck isn’t so much either (long story – you don’t want to hear it)). So for a teardrop, it doesn’t really matter much. .04 should be plenty thick for covering a teardrop – they use .04 – 05 inch thick for load carrying panels on race cars etc.

For aircraft apps; 5052 was used for shims/spacers. Structural was 2024, 6061, 7075.

Used other alloys in tooling only

Ageless wrote:For aircraft apps; 5052 was used for shims/spacers. Structural was 2024, 6061, 7075.
Used other alloys in tooling only

True dat, it's also used as expandable core in honeycomb core sandwich construction; so, it has its place. It is however a reasonably priced alloy that a consumer can buy. When I was checking around for another project, 2024 T3 sheet was double the cost of 5052 T-34 which will make a project’s cost go through the roof in a hurry. Still, 5052 H32 or H34 has nearly twice the strength of the 1XXX and 3XXX alloys.

Incidentally, the guys in the shop love the 6061 because it bends easily. Engineers hate it for the very same reason. Also note that due to labor costs we seldom make bent sheet parts anymore – most everything is machined these days (mostly 7050).

kennyrayandersen wrote:

laoutdoorsman wrote:somebody correct me if im wrong...but 5000 series aluminum is marine grade....not needed for a trailer roof...

I’d be happy to. The series 1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, and 7xxx, have nothing to do whether or not the alloy is suitable for any given application such as ‘marine’, ‘outdoor’, etc., but rather refers the alloy family. Within that family the various other sub alloys and heat treats vary the properties of strength, workability, corrosion resistance etc. Even among a single family the corrosion resistance, for instance, could vary dramatically.

The 3XXX alloys are not so structural, but form easily (if I remember correctly – they don’t even show up in the Mil-handbook, so we don’t use them for ‘structural’ applications, and by that I mean a primary load carrying member. The 5XXX series has better strength properties, and can generally be bought in one of your larger cities. It is considered a low-grade structural material. It used structurally in home-built cars etc.

Having said that, you aren’t using the aluminum as a structural alloy (the top of the truck isn’t so much either (long story – you don’t want to hear it)). So for a teardrop, it doesn’t really matter much. .04 should be plenty thick for covering a teardrop – they use .04 – 05 inch thick for load carrying panels on race cars etc.

hmmm...well, then i wonder why all the aluminum boat builders use and insist that 5000 series alum is the only plate/sheet to use....BUT....its irrelevant to this post topic....so....

This site gives a good explanation of aluminum alloys that is pretty understandable.

http://en.wikipedia.org/wiki/Aluminium_alloy

Hope this helps.

Cheers,

Gus

I used the 102" wide .40 from a Trailer Repair place. About 11.00 a ft if I remember. unwieldy to transport and work with. DO be on hand as its cut off the roll as to safeguard as best you can.

Mike

laoutdoorsman

somebody correct me if im wrong...but 5000 series aluminum is marine grade....not needed for a trailer roof...

kennyrayandersen

I’d be happy to. The series 1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, and 7xxx, have nothing to do whether or not the alloy is suitable for any given application such as ‘marine’, ‘outdoor’, etc., but rather refers the alloy family. Within that family the various other sub alloys and heat treats vary the properties of strength, workability, corrosion resistance etc. Even among a single family the corrosion resistance, for instance, could vary dramatically.

laoutdoorsman

hmmm...well, then i wonder why all the aluminum boat builders use and insist that 5000 series alum is the only plate/sheet to use....BUT....its irrelevant to this post topic....so....

If you don't mind my saying so, it may indeed be relevant, if not loosely associated with the thread starter's orginal questions...



Now I'm not formally trained as a structural engineer nor have I worked professionally with aircraft aluminum structures, but I did stay at a Holiday Inn Express last night.

Kenny's explanation MAY have one or two clues as to why boatbuilders spec the 5000-series alloys, and that is perhaps due to it's level of corrosion resistance... yet it may retain some workability... more workability, than, say, the 7000 series alloys, but with a more-than-satisfactory level of corrosion resistance for a marine environment. It would seem to me that the higher the level of corrosion resistance, the lower the level of workability.

Mike Angeles

I used the 102" wide .40 from a Trailer Repair place. About 11.00 a ft if I remember. unwieldy to transport and work with. DO be on hand as its cut off the roll as to safeguard as best you can.

I'm curious. How does one straighten aluminum at a home shop to lay flat after it's been shipped and stored in a roll?

Thanks...

Let me throw this out there... I'm building a TD that's like the Cubby, the roof will have no plywood underneath it, only the spars and the insulation.

From all I've read so far, I'm getting the impression that the aluminum skin provides much of the rigidity of the trailer with this type of design.

Now we've just established that the 3003H16 aluminum has less structural strength than the 5052H32 aluminum. Does this mean if I use the 3003H16 that I could run into problems in the future with the skin tearing around the screws/trim pieces?

Sorry about the tread wandering:
From http://www.keytometals.com/Article99.htm
Small boats are fabricated from a wide range of aluminum sheet alloys, mainly in the 5xxx and 6xxx series. These have an optimum combination of strength, cost, ease of fabrication, and corrosion resistance. Generally, 5052-H32, 5052-H34, or 6061-T6 is used for small hulls that need no stretch forming. Where stretch forming is employed, 6061-T4 sheet, which may be subsequently artificially aged to the T6 temper, is utilized. Extrusions of 6061 or 6063 are used for structural and decorative sections, such as keels, chines, gunwales, and spray rails.
Rivets of 2117, 6053, or 6061 are recommended. Generally, a rivet should be neither much harder nor appreciably softer than the sheet to be joined, and it should have similar mechanical properties.

5052, as it turns out is one of the few aluminum alloys that can be easily welded (that’s why it is used for expandable aluminum honeycomb core). Also include in this small group of weldable alloys is 6061. It does mention that 5052 does also have very good corrosion properties, which is certainly a bonus for marine applications, but it’s not hugely better than some other alloys. If you read through the rest of the article, you see that where higher strength is requited other non-5052 alloys are used.
The workability and corrosion resistance is not necessarily connected, though it could be said that the higher the strength the less it is formable.

I used the 102" wide .40 from a Trailer Repair place. About 11.00 a ft if I remember. unwieldy to transport and work with. DO be on hand as its cut off the roll as to safeguard as best you can.

Good advice, two people working together will help you keep from damaging either the aluminum sheet or yourself!

I'm curious. How does one straighten aluminum at a home shop to lay flat after it's been shipped and stored in a roll?

It’s not a small tight roll, but kind of a bigger roll, so the deformation shouldn’t be so much that when you undo the roll the material should spring out and lay flat (elastoplastic, not plastic). If you roll it too tight, it won’t unroll ‘right’

alanv73 wrote:Let me throw this out there... I'm building a TD that's like the Cubby, the roof will have no plywood underneath it, only the spars and the insulation.

From all I've read so far, I'm getting the impression that the aluminum skin provides much of the rigidity of the trailer with this type of design.

Now we've just established that the 3003H16 aluminum has less structural strength than the 5052H32 aluminum. Does this mean if I use the 3003H16 that I could run into problems in the future with the skin tearing around the screws/trim pieces?

The stiffness of all aluminums (especially the ones we are talking about here) are all pretty much about the same (Young’s modulus is around 10.4 E6 psi). What is different is the stress level that permanent deformation (yielding) takes place. The stronger the alloy and heat treat, the higher the yield point. Keep in mind that you aren’t going to have enough stress to cause either of these alloys to permanently deform (unless it gets smacked by something). So, in the end, it doesn’t matter which one you pick – get the one that is available. They both will provide the same stiffness! Now if you were building a plane, or a car, that would be a different story.