Trailer Frame Tube vs C-Chanel

[762X39]

There is a tutorial on the Tiny Trailer and Teardrops site regarding frame construction (lots of good info in general for trailer building). It is worth a visit just to get ideas.
http://tnttt.com/

 

[Capt Eddie]

1/4" luan on two sides with 1" ethafoam in between is cheaper and better r value. Pull the plastic wrap off of the foam before you glue the luan to it. It is unbelievably strong. For $35 dollars you can make up a panel and see how light and strong it is. Cheaper then $265. 2" C channel can come in many different thicknesses.

 

[Capt Eddie]

I'd use tube, a trailer of that size I'd go 2"x3" 3/16". My 30' Jayco uses 2"x6" tube on the frame and the tongue and weighs in at 7500 lbs. Our 44' enclosed race trailer with living quarters is also tubed, including the gooseneck and it has triple 8 lug axles. This is why trucks have evolved from C frames to boxed frames too.

2 x 3 x3/16 would be overkill on something that small. The weight is 3X that of a 2" C. Big production uses coated material for the Tube frames

 

[IGBT]

Have you given any consideration to a relatively light gauge steel frame and aluminum siding? We found this construction method to be quite quick and it seems very strong. It is definitely easy to fabricate using a simple MIG welder. Build the base out of the c-channel as recommended but build the upper structure out of light gauge tube.

Our garage pod is built almost entirely of 0.062 1x1 and 2x1 steel tube, with a few members in key areas (hinge area of ramp door) being 0.125 wall square tube. Aluminum is 0.062 for walls/bottom and 0.040 for roof.

I also like the Nidacore idea but figured I would be constantly reinforcing areas where I wanted to attach heavy items (workbench, shelves, jackstand mounts).

 

[Strider]

Wow! Lots of great points!

I am on the fence between c-channel and tube. I look at the Aussie UEV440 and the frame seems to be tube with holes for venting/cleaning. Of course, it's hot dip galvanized.

Capt Eddie makes a good point about c channel.

For tube I have thought of 2x4 or 2x3 1/8 wall tubing with 2" holes cut at intervals. I would cover the holes, pour in good rust preventative paint, and then slosh around. The holes would then be uncovered to allow for any humidity etc. to escape.

The C channel would of course be easier, but I am worried about how strong it is all around, though maybe this is not really an issue beyond my misunderstanding?

I was thinking of the box frame pretty much like IGBT described.

One thing about the c-channel is will it allow installing the Timbren axles easily.

I will have to look at the links for the tiny teardrops.

 

[Strider]

1/4" luan on two sides with 1" ethafoam in between is cheaper and better r value. Pull the plastic wrap off of the foam before you glue the luan to it. It is unbelievably strong. For $35 dollars you can make up a panel and see how light and strong it is. Cheaper then $265. 2" C channel can come in many different thicknesses.

What do you use for glue? Your idea is to then fiberglass over the luan/foam sandwich? How about aluminum or galvanized steel thin sheet instead of the luan? Maybe on the outside?

 

[Capt Eddie]

I am trying to figure out why you want to go through all of the work for the uses of tubing? You can get a 1/4 thick C channel to do the same thing. The supports that you will hang the spring saddles on need to be 1/4 inch wall thickness. Tubing does great for interior walls that need structural support.


Liquid nail exterior grade for the glue. For a fiberglass exterior I use 1/8 glass steel sheets. 4' x 8'. Yes you can use sheet metal instead of luan. But luan gives a vertical strength that metal sheets can not give. I like the wood look. I would use a clear poly that you would use on gym floors. That is tough as nails. I do not know the look you are going for. Remember that the interior structures will add strength and rigidity to the whole structure. Cabinets, bed frames??????

 

[Strider]

This is how the TImbren axles attach to the frame. Seems pretty straight forward and should work with tube and c, though I think 3" minimum with either is necessary.

Here is how those axles attach-from their website: http://www.etrailer.com/Trailer-Axles/Timbren/ASR3500S06.html

In the last picture is looks like the axle is attached to a c-frame.

 

[Strider]

I am trying to figure out why you want to go through all of the work for the uses of tubing? You can get a 1/4 thick C channel to do the same thing. The supports that you will hang the spring saddles on need to be 1/4 inch wall thickness. Tubing does great for interior walls that need structural support.


Liquid nail exterior grade for the glue. For a fiberglass exterior I use 1/8 glass steel sheets. 4' x 8'. Yes you can use sheet metal instead of luan. But luan gives a vertical strength that metal sheets can not give. I like the wood look. I would use a clear poly that you would use on gym floors. That is tough as nails. I do not know the look you are going for. Remember that the interior structures will add strength and rigidity to the whole structure. Cabinets, bed frames??????

I will probably go with 3" c. Do you think the tongue should be a separate piece or one piece with the frame?

The look I am inspired by us thr UEV440.

 

[tgreening]

This is how the TImbren axles attach to the frame. Seems pretty straight forward and should work with tube and c, though I think 3" minimum with either is necessary.

Here is how those axles attach-from their website: http://www.etrailer.com/Trailer-Axles/Timbren/ASR3500S06.html

In the last picture is looks like the axle is attached to a c-frame.

View attachment 272337View attachment 272338View attachment 272339
View attachment 272340

Notice in the second picture the angle extension on the side of the box tubing has gussets. Why do you suppose that is? Would your C-channel have that? No, it wouldn't.

How many trailer builds have you seen in here done with structural C? C-channel is really meant to be backed up against something and not free standing support on it's own. Two channels back to back would make what amounts to an I-beam, stronger together than they would be individually.

I'd take a .120 wall 2x3 piece of box any day over 3" C with a 1/4" web. If it's been properly welded you will destroy the tube before you break the weld and in that case you'll have much bigger things to worry about.

I think you might be over-thinking this a bit and making it more complicated for yourself than you need to.

 

[brushogger]

Different parts of the trailer should be made of different material based on the structural strength needed in each application. The tongue itself should be C channel. Structural areas may be angle or square. As a whole you would not want any more closed area then necessary. These are areas that can hold water and vermin. Look at some commercially made trailers. They are built the way they are for a reason. I do not think you will find much square tubing on high production builds. There is to much liability for tubing failure.

Please don't take this a any kind of criticism because I have no experience in this area. I'm also wanting information as we are looking at off road teardrops. The Moby XTR and Adventure Trailers use what looks like a 2" heavy wall tubing. Why would they use that instead of C channel? When i ask this, I'm not saying they have anymore expertise than you since this is your trade. I'm just curious. I have also read about the condensation issue you mentioned. Is this just inherent to the design, or is there some other way of putting the trailer together to prevent this? Thanks for any info you can provide.

 

[spressomon]

Not an SE...but put my then Kimberely Kamper Sports RV trailer through 10's of thousands of miles of tough use without issue. KK uses 2"x5" rectangular tubing for their frame/chassis.

 

[Capt Eddie]

Please don't take this a any kind of criticism because I have no experience in this area. I'm also wanting information as we are looking at off road teardrops. The Moby XTR and Adventure Trailers use what looks like a 2" heavy wall tubing. Why would they use that instead of C channel? When i ask this, I'm not saying they have anymore expertise than you since this is your trade. I'm just curious. I have also read about the condensation issue you mentioned. Is this just inherent to the design, or is there some other way of putting the trailer together to prevent this? Thanks for any info you can provide.

If you were manufacturing these every day. You would be able to have the metal hot dipped galvanized and not worry about all the rust. There frames are probably totally welded up before going to the dipper. I will say that working with tubing is a lot easier then working with the channel. You only have one full size workable surface in a channel. Where tubing gives use 4 workable surfaces. There are major differences in full scale manufacturing and shade tree building. I do a combination of all. In the perfect world and a half Million dollar shop tubing is easier for robotics to work with. Then send it all out to be coated. Galvanizing adds about $500 to the cost. Powder coating $350. Hand priming and painting $100.

yes you would build a double beam for the axle saddles.

I would have the tongue come out of the frame. This will give you 4 inches more clearance. When you have to go in reverse you do not have to worry about the frame catching on anything. Make a drop adjustable tongue with it built in the highest position. This will allow it to be used with SUV as well as trucks

I just reviewed your drawing. With the tongue set up as you have it, I would use whatever means to have the trailer frame level with the tallest vehicle that you could use. Then have the collar adjustable downward to be used with shorter SUVs. That might mean using 6 inch tall metal as spacers for the right height

 

[Strider]

I would have the tongue come out of the frame. This will give you 4 inches more clearance. When you have to go in reverse you do not have to worry about the frame catching on anything. Make a drop adjustable tongue with it built in the highest position. This will allow it to be used with SUV as well as trucks

I just reviewed your drawing. With the tongue set up as you have it, I would use whatever means to have the trailer frame level with the tallest vehicle that you could use. Then have the collar adjustable downward to be used with shorter SUVs. That might mean using 6 inch tall metal as spacers for the right height

Not sure what you mean. I am a visual person, so sometimes descriptions don't work well in my brain.
Do you mean that I should have the tongue as I designed it-as a separate unit-coming out from under the frame, or do you mean the tongue should come out of the frame as part of it?

 

[Strider]

OK
Lets say I go with 2x3 or 2x4 1/8 tubing for the frame (I think c channel may be better for the tongue, or the same tubing but in 3/16 as per Capt Eddie's advice). Regardless of what I use I will use gussets at the corners.

Will cutting 2" holes at regular intervals, staggered, weaken the structure? I am thinking that the holes will lighten the weight a bit, but more importantly allow for any humidity to evaporate easily and I can give the inside as well as the outside several coats of good paint-maybe POR 15 or something.

I have attached a drawing of what I mean.


And thank you to all of you for taking the time to give your opinion and advice!