Trailer construction help

[jamorgan3777]

I know there are pros/cons to each choice, but looking for the consensus on what to build my trailer out of.

2"x2" by 0.120 square tube?
2"x3" by 0.065 rectangle tube?
3"x3" by 0.065 C channel?

Beginner welder here. Thanks in advance for any/all insights.

JAM

[tony.latham]

I went with .120" 2" square tubing since the thinner gauges are a bit more challenging to weld.





Tony

[saltydawg]

I used 2x3 tube 14 gauge for the frame, 2x3 tube 11 gauge for the tongue, deck size 5.5 x 10. Final weight for just the frame and tongue no running gear is a little over 300 lbs.

No issues with welding the 14 gauge ( .084 ) at all, or with the 11 gauge ( .120 ) either with a mig welder running .035 wire and co2 for gas.

[jamorgan3777]

@tony.latham - Loved your build thread. I spent most of last night going through it. You answered a lot of my questions. You convinced me to try the "bedliner over fiberglass" route.

@saltydawg - That trailer is close to what I am trying to build. Wanted step sides around along with the fenders (as yours appears to have). Question, what is the angle iron on the outside for? Wouldnt the expanded or diamond plate go on top of the "shelf"?

Thanks for the quick reply.

[twisted lines]

Someone on this form posted 1.5" X 2"
If I was starting another I would start with that but it would surely be .120 no matter which I chose.
With angle for axle supports.

[saltydawg]

@tony.latham - Loved your build thread. I spent most of last night going through it. You answered a lot of my questions. You convinced me to try the "bedliner over fiberglass" route.

@saltydawg - That trailer is close to what I am trying to build. Wanted step sides around along with the fenders (as yours appears to have). Question, what is the angle iron on the outside for? Wouldnt the expanded or diamond plate go on top of the "shelf"?

Thanks for the quick reply.

The deck goes all the way to the edges, the angle is for the wall panels to sit on and be attached to. My walls will be diy insulated structural panels 1.5 inch of foam and 2 layers of .055 fiber glass.

If you look close the edge is 2 angles, one is "turned" in to support the edge of the floor, the other is lower and "turned" out. This gives me a metal bottom to sit the walls on and 3 inches of vertical surface to bond the walls to. Plus I will have some steel tube built into the walls as a minimal frame

If you search my old posts from like 2012, you will see I was going to do SIP panels bonded to the frame. I also love the sawtoothxl look so I changed my design to mimic his shape. He is now doing the sawtooth unlimited. But he is using the design system I was going to do 8 years ago, but he did the research on it and refined the system. Granted it is also how they do the expo trailers in Australia, he just is posting it in video form. Watch the video below around the 12min mark to see him putting a panel on.

https://www.youtube.com/watch?v=74FtcfB33NM&t=5s

[saltydawg]

double post

[MickinOz]

I know there are pros/cons to each choice, but looking for the consensus on what to build my trailer out of.

2"x2" by 0.120 square tube?
2"x3" by 0.065 rectangle tube?
3"x3" by 0.065 C channel?

Beginner welder here. Thanks in advance for any/all insights.

JAM

My thoughts:
0.065" is only 1.6mm

a 3 x 3 C channel in that thickness is too flimsy in my opinion.

2 x3 RHS (rectangular hollow section is what we call tube in Australia) in 1.6mm I would consider JUST strong enough for an on-road camper, BUT only if you are a very competent welder.
Less than good welds on such thin material are a disaster waiting to happen. The other thing I'd worry about is distortion while welding. Don't want your frame to look like the start of a double helix.

That leaves 2" x 2" X .12 (3mm)square tube. That'll work. Plenty of meat for an amateur welder to bite into.
Easily solid enough to directly weld the spring mounts to the frame. You'd be able to through-bolt anything you wanted, and not lose sleep about crushing the tube.
You say you are a beginner welder, so I highly recommend researching how to weld a frame without the welds pulling it all out of shape.

I can stick stuff together with a stick welder, but I still ask for help from qualified welder friends for really important structural stuff.

P.S. my welding improved out of sight when I bought an auto darkening helmet. When you don't have to use one hand to operate the eye protection, you can put on a welding glove and use that hand to steady the rod to get started, etc.
I'm talking stick welding. If you have a MIG things get better they tell me.

[MickinOz]

Someone on this form posted 1.5" X 2"
If I was starting another I would start with that but it would surely be .120 no matter which I chose.
With angle for axle supports.

That's plenty of meat, especially at .12 (3mm)
You guys sure like to build strong.

Here in Oz, all steel sizes are available to order. Not hard to get at all.
However, the local steel yard commonly stocks 0.065 (1.6mm) and 0.1 (2.5mm) if I want off-the-shelf.
I was in there the other day, and noticed he had a rack of "fence posts"
These are 50 x 50 x 2.5mm square tube, galvanised, pre-cut to 1.8, 2.1 and 2.4 metre lengths. That's the metric equivalent of 6, 7 and 8 feet. 2" x 2" x 0.10"
A quick bit of mental arithmetic as I was standing there told me I could get all the steel for a 8 x5 galvanised steel frame minus hitch axle and springs for less than $200, with minimal off-cuts..
Guess what my next frame will be made from.

[GTS225]

A little tip from me to all of you. I'll use Saltydog"s pic to illustrate, but when you build a frame, plug all open tubing ends. I can readily count ten, possibly twelve, open ends that paper wasps will attempt to build a nest in. I tend to do a 45* angle cut on the tube ends, and weld on a thin end cap, even if it's .060 sheet steel to keep the creepy crawlies from taking up residence in my frame.

I've got a boat trailer right now that I've had to spray this season, because the 2"x3" tongue is open right at the ball coupler, and the damn wasps built in the end of it.

Now, if you don't have wasps and hornets in your neck of the woods, more power too ya, but I'll bet you have other critters that you don't really want hitching a ride.

Roger

[MickinOz]

A little tip from me to all of you. I'll use Saltydog"s pic to illustrate, but when you build a frame, plug all open tubing ends. I can readily count ten, possibly twelve, open ends that paper wasps will attempt to build a nest in. I tend to do a 45* angle cut on the tube ends, and weld on a thin end cap, even if it's .060 sheet steel to keep the creepy crawlies from taking up residence in my frame.

Now, if you don't have wasps and hornets in your neck of the woods, more power too ya, but I'll bet you have other critters that you don't really want hitching a ride.

Roger

Well, no actually
Well, maybe, but nothing I'd worry about much. Maybe the odd taipan or brown snake, but they'd only climb in if they thought there was prey in there.

[saltydawg]

I agree on thickness .084 or 14 gauge which are standards here would be the min I would go, and not for real structural parts. That .1 inch sound about perfect for most stuff on a lighter trailer. I used 11 gauge/.120 for the tongue framing.

As for the pre galvanized posts, you will need to grind of the galvanizing every where you weld or it gets nasty for fumes.

Yes I the open ends are getting sealed.

And Mick you need to try mig welding, it is very easy.

[PCO6]

I've built trailers with 2"2"x11g and 2"x3"x14g and both work fine. The key is the design of the trailer itself.

As an aside, I've built several cars for off road racing and the rules wouldn't allow the use of square or rectangular tubing for any part of the frame. It was round only for strength reasons. I don't think I've ever seen a trailer frame made out of round tubing! ... and I'm not about to try one.

[PCO6]

... P.S. my welding improved out of sight when I bought an auto darkening helmet.

My welding improved when I started using reading glasses under my auto darkening helmet!

[MickinOz]

And Mick you need to try mig welding, it is very easy.

Setup costs mate. I'll stay with my 40 year old stick welder.....