2x3x1/16 rectangular tubing - why don't more people use it?

[jmtk]

I’m working to finalize the specs for my trailer frame so I can get the welder going on it. I’m trying to keep the overall weight down since we’ll be towing with a small car. The welder wants to go with 2x3x1/8 rectangular tubing for the A-frame tongue (I’m happy with that), the same tubing for the 5x8 perimeter of the frame, and 2x2x1/8 square tubing for the cross-members. I want two cross-members, one at 28” center and the other at 77” center from the front. I’m also going with a Dexter Torflex axle which gives me a third structural cross-member and will be around 54” from the front.

I know lots of teardroppers are using 2x2x1/8 tubing and I’m comfortable with its strength for the rectangular frame and cross-members. Then I came across a thread on the forum http://www.tnttt.com/viewtopic.php?t=4918 that discusses 2x3x1/16 rectangular tubing. Powderburn used it on his Predatear, and Andrew later chimed in saying it had the exact same strength as 2x2x1/8 square tubing, but was about a third less weight. That sounded like the ticket to me. If I used it for the 5x8 perimeter and 2 cross-members, it would drop my trailer weight by darn near 60 lbs from what the welder was suggesting! Or by 36 lbs if 2x2x1/8 was used all around!

Has anyone else used this 2x3x1/16 tubing? Andrew’s data tells my geek brain that it is the strength equivalent of 2x2x1/8 square tubing (Andrew - where do you get section modulus info from, do you calculate it yourself or pull it off a chart somewhere?), but my complete lack of experience in this area, its apparent lack of use by the teardropping community, and the paranoid mom part of me who wants to be sure I’m pulling a safe trailer makes me a bit nervous. I’m sure the welder will think I’m nuts and try to talk me out of it, and unless I have some good ammunition, he’ll probably succeed. I only have two data points: section modulus (which I really don’t even know what it is, but is apparently indicative of strength), and Powderburn’s tear.

Now, there was some question in the original thread about if it was actually 0.083 thick (~1/12) rather than 1/16, but that is still stronger and lighter than 2x2x1/8.

Why isn’t this more widely used by teardrop builders? It seems like a great choice for being strong and light weight.

Thanks,

Jeanette

PS - Clearly I'm obsessing over this, but like Dean, I'm Norwegian

[Bill Larson]

thats what i used on our teardrop,light and worked great. so know problem as far as strenght.we us the same tubing for streetrod frames

[Guy]

Dear Jeanette,

The teardrops4vets frame, which is actually a 1983 Coleman popup frame uses 1 1/2" x 3" x 1/16" steel. The cross pieces are even less than 1/16". I just travelled 270 miles in 4 1/2 days at speed limit with about 1800 lbs on it. It never even swayed the slightest, even with small tires.






For more images see my gallery or Todd post of the pics.
http://www.mikenchell.com/forums/album_personal.php?user_id=109

[jplock]

That is what my frame is made from this 1/16 x 2 x3 on the outer perimeter and A frame towbar. I used 1/16 x 1 x2 for the cross members. Before the suspension was added 2 men could handle it easily. You can see it in my album.

JPLOCK

[jmtk]

Thanks for your input, guys! I suspected there were more builds out there than just Powderburn's using this size tubing.

Bill - Your frame appears sparse compared to many on this forum, but then apparently many are overbuilt. Maybe yours is actually about right for a teardrop. How heavy is your trailer when loaded? I must say, you have a very handsome trailer!

Guy - It was interesting to hear that a commercial pop-up used similar steel, and has survived for more than 20 years!

JP - I envision my frame to look much like yours, except I'd have a Dexter Torflex axle replacing the center cross-member.

Thanks again!

Jeanette

[Bill Larson]

weighs about 800 lbs loaded.thanks for the complement ,sure turns a lot of heads.Bill

[Joanne]

Hi Jeanette,

There has been a lot of discussion about overbuilding the trailers. Not too long ago there was a long thread about the feasibility of a framless trailer. Most of us ignore the fact that the cabin itself is a strong box structure that adds an amazing amount of strength and rigidity to the trailer once it's attached. Many of us (myself included) build the trailer frame as if it has to be strong enough to be a flatbed utility trailer, but that's not necessary. Were I to build again, I would go much more lightweight than I did. (I converted a big, heavy boat trailer)

A-frame tongue: 2x3x1/8
Parimeter frame: 2 x 3 x 1/16
Cross members: 1 x 1-1/2 x 1/16

Some might consider even this to be over-built, but it would make me feel safe.

Keep one thing in mind though. The trailer will not be very ridgid once it's completed. I think that's what bothers people. Once the cabin is built on the frame it will become a very ridgid unit.

Once the frame is built, don't just sit in on it's wheels and start building the cabin. Be sure to support it on all 4 corners (automotive jack stands or something) and verify that it's level down its length and across its width. This will make your build much easier and less likely to be out of square.

Just my .02 worth,
Joanne

[jmtk]

Joanne,

Yup, I've read many "overbuilt" threads, which is why I'm trying to go lighter. But of course I want it to be safe. There are two places I'm paranoid about this build - the trailer chassis and the electrical. As I learn more about the electrical side, I'm less worried about it. With no steel/welding experience, however, I'm less comfortable with knowing how far (ie, light) I can go with the chassis and still be safe cruising at highway speeds or rattling down some washboard roads. Thanks for your input.

Hey, I hope to see you and the Desert Dawg sometime! We head for Zion at least once a year, and that's just over the border for you.

Jeanette

[alaska teardrop]

Jeanette, Here is the link to Andrews site & chart on steel. It shows 2x3x14 gage (2x3x1/16).

http://www.angib.pwp.blueyonder.co.uk/t ... tear84.htm

1/16" is somewhat more difficult to get a good weld. Both to itself and to a thicker material. Also, more susceptible to cracking at the weld due to flexing (rough roads). IMO.

Fred

[jmtk]

Hi Fred,

I'm quite familiar with that link Thanks for making sure I knew about it, though. The points about the thinner stuff being harder to weld and more susceptible to cracking is interesting. The vast majority of roads we'll travel with our trailer will be pavement, but we like to play in the desert southwest, and a lot of really good places are down washboard roads. We'd be taking our time down them, but it'll still rattle around. It'd be nice to know how Powderburn's is holding up since he made a real off-road tear.

Thanks for you input!

Jeanette

[alaska teardrop]

Jeanette,

Glad to hear that you're way ahead of me. You're obviously a thoughtful pioneer in strong lightweight steel frames! Please don't take my comments as discouragement.

To rephrase: Instead of 'difficult'. 'skill & patience'. Tight fits, readjustment of the feed & amps for each type & thickness of weld, ect. becomes more precise with thiner material.

As to flexing. Good use & placement of lightweight dual purpose gussets & maybe diagonal trusses?

I'm very interested to see what you're design might be. pics.

Fred

:

[jmtk]

You're obviously a thoughtful pioneer in strong lightweight steel frames!

Fred, I'm not so sure I want to be a pioneer, aren't they the ones that wind up with arrows in their backs? I was hoping to find out if I could follow safely in others' footsteps

Jeanette

[Joanne]

Hey Jeanette,

Getting together in Zion sounds like fun! It might even be a good place for a few of us southwest folks to rendezvous and camp for the weekend.

Joanne

Joanne,

Yup, I've read many "overbuilt" threads, which is why I'm trying to go lighter. But of course I want it to be safe. There are two places I'm paranoid about this build - the trailer chassis and the electrical. As I learn more about the electrical side, I'm less worried about it. With no steel/welding experience, however, I'm less comfortable with knowing how far (ie, light) I can go with the chassis and still be safe cruising at highway speeds or rattling down some washboard roads. Thanks for your input.

Hey, I hope to see you and the Desert Dawg sometime! We head for Zion at least once a year, and that's just over the border for you.

Jeanette

[alaska teardrop]

I was hoping to find out if I could follow safely in others' footsteps

Nope, You're lead dog on this one.

'If you ain't lead dog, the scenery never changes!';)

Fred

[jplock]

Here is my lightweight 2x3 steel frame Rig. The wooden framework adds more strenght to the frame. The tounge weight at this point is about 40 pounds. I took it for a test tow and bounced the rig over a good Oklahoma pot hole. It survved!