What kind of steel tube should I use for trailer frame?

[mattiker]

Picked up a decent axle with leaf springs not too long ago, and am starting on the actual frame itself. Building a 4x6 camper that will be under 1000 lbs and was wondering if there is a particular kind of steel tube that would work best for a frame. I've seen some builds with 2x3 tube that is 3/16 in thick, was wondering if there are other options that might work better. End goal is to have a trailer with a fixed floor and removable top. Thank you.

[saywhatthat]

Just got the engineered frame for my next off road trailer 9 by 4.5 wide 5 high with open top .Using trailtop / railtop modular trailer building components for the pod Was surprise most is to use 1,5 '' tube.120 wall 3500 axle 2000 lb. springs

[GTS225]

FWIW, I'm driving around (in good weather), in a '23 T-bucket with a frame of 1.5"x3"x.120" wall tubing, and it's showing no signs of stress.
My tear build is starting out with a self-built frame of 2"x2"x.120" wall tubing, and I'm quite sure I won't have any problems with it.
Take a look at a commercially built foldown's frame. You might get a bit of a shock.

Disclaimer; I'm not an engineer, nor have I ever had any schooling in that discipline.

Roger

[working on it]

from the second week into my build (October 16, 2011)

I had a 50"x60" (220 lb.) frame on 8" wheels with an overall length of 102" to start with. Now, 2 weeks later, I've reinforced all areas, boxed in a 50" x 96" area with 1.5"x 2.5" tube, and lengthened and strengthened the tongue with new 3"x 3" x .188 square tube (to a new total length of 140"). Plus, I've installed new 5 on 4.5" hubs, and gone to 14" wheels. I haven't put the new fenders on yet, but I estimate that the new rolling weight at a frog's hair under 500 lbs. My goal at coming in at under 1000 lbs/100 lbs tongue weight seems very iffy right now.

* Actually, it came in at exactly 400 lbs, with fenders on, wheels & tires, and a 3/4" floor installed and polyurethaned....

• starting point: derelict 50" x 60" frame (w/11 gauge tubular steel perimeter & angle steel cross members)
• replaced single beam tongue with longer, thicker 3"x 3" x 3/16" tube
• 1.5" x 2.5" 11 ga. tubing 24" added... to the rear, with center spine also
• ...12" added to front, with center spine sistered to tongue and three cross members
• completed, but wish that I'd reversed the addition configuration (caused too much rear bias, at first)
• 400 lbs after deck was added

* I left the new end tubes open (instead of being capped/sealed), so I could install/access wiring inside, and let any subsequent moisture have a chance to evacuate, instead of being trapped inside. So far, the added steel tubing hasn't rusted at all, and made the frame easier to work on, and stronger than if I'd used 1/4" angle steel as the extension pieces, as I had intended originally (to be bolted together, not welded on).

* The 1/2" plywood floor was initially bolted to the angle steel cross members with 3/8" carriage bolts, but after layering-on a 1/4" Luan sheet (using TB2), I used Tek screws to permanently secure the completed floor to the perimeter of the frame (thirty-eight screws thru wood into the tubular steel). The resultant rolling trailer was much stronger than needed (exception: the spindly 1.25" square-tube axle, which I replaced in 2014, with a 3500 lb Dexter axle, 3000 lb springs, & massively-strengthened frame rail additions, using 1/4" angle).

* The 11 gauge tubing would've been quite adequate, but an over-tightened spring hanger nut had caused it to rip loose, and the new complete axle/spring/hanger assemblies needed a repaired and/or reinforced frame rail to mount on. Otherwise, 11 gauge was fine. 2" x 3" x .188" is overkill, especially if it is on a 4x6 sub-1000 lb trailer (my 4x8 is over 2000 lbs, so I went big! on the steel).

* Unless you already have the steel tubing, then get (1.5-2)" x (2.5-3)" tubing; 11 gauge (.120") will be plenty strong for your usage.

[tony.latham]

Picked up a decent axle with leaf springs not too long ago, and am starting on the actual frame itself. Building a 4x6 camper that will be under 1000 lbs and was wondering if there is a particular kind of steel tube that would work best for a frame. I've seen some builds with 2x3 tube that is 3/16 in thick, was wondering if there are other options that might work better. End goal is to have a trailer with a fixed floor and removable top. Thank you.

3/16" 2x3" tubing is gross overkill for a teardrop chassis. A properly constructed teardrop cabin is a torsion box ––stiff–– it doesn't need a stiff chassis.

It'll scare you to look at what was used in the chassis of the old Kit teardrops. But it worked. 1/8" 2x2 tubing is fine for a teardrop chassis. .083" 2 1/2" x 1 1/2" is stronger and lighter but more challenging to weld.



I'm talking about the chassis frame here, not the tongue. That's a different issue.

End goal is to have a trailer with a fixed floor and removable top.

I assume you are talking about a removable teardrop cabin (with an attached floor) and a separate floor for the chassis.

I guess what you have to ask yourself, is what you are going to haul on the trailer after the cabin is removed. But keep in mind, if you build a utility trailer that can haul a 3,000-pound load, the springs will bounce the crap out of your little teardrop cabin.



Tony

[KTM_Guy]

I used 2X2X1/8 for my build. It’s over kill. I built going by what others have done. After I had the frame built I was talking with my brother ( Who is a welding engineer) and he ran some numbers on different size tube and Channel. My next build will be 2X3 16 gauge. It is actually stronger than the 2X2X1/8 that I used and 30-40% lighter. He did Caution that joints needed to be tight fitting and in low stress areas. And the welds need to be of high quality. If you are not good welding on thin metal you can go up to 14 gauge which is the size between 16 gauge and 1/8” (11 gauge).

Todd

[Aguyfromohio]

I used 2X2X1/8 for my build. It’s over kill. I built going by what others have done. After I had the frame built I was talking with my brother ( Who is a welding engineer) and he ran some numbers on different size tube and Channel. My next build will be 2X3 16 gauge. It is actually stronger than the 2X2X1/8 that I used and 30-40% lighter. He did Caution that joints needed to be tight fitting and in low stress areas. And the welds need to be of high quality. If you are not good welding on thin metal you can go up to 14 gauge which is the size between 16 gauge and 1/8” (11 gauge).

Todd

We used 14 gauge and it seems OK. 2 x 2 throughout, 2 x 3 for the two the A frame hitch pieces
Our weld shop talked us out of 16 gauge, said it was thin enough it was trouble to weld and so he'd need to charge us more overall for the thinner 16 gauge frame.