Trailer Frame Feedback Request

[john61ct]

But you can always go closer to 50/50 to balance heavy stuff on the A-frame

Farther back is better for handling.

I've toyed with the idea of a main under chassis where the Axle-less can slide forward or back as the buildout proceeds.

Only put in the wheel-wells once that has been finalized

the shell of the living pod mounting on an outer rail that is above "flatbed height" so unaffected by changes to the lower half.

Lets you put in outside-oriented accessible storage, modular around the sides, and a lowered floor for a basement that does not require lifting the mattress.

Best to use 3D for modeling, lighter spaceframe tubing other than the spine and the Axle-less mounting rails.

 

[CampStewart]

With a long enough straight extension, and a normal angle A-frame, best of both worlds.

I've never even seen a live-in unit with only a straight tube, single point connection to the front-most crossbar?

Not for me. . .

I get it that you don't like a straight tube frame design but why? You seem to have a strong opinion I am trying to learn something from you. Lots of boat , motorcycle, snowmobile, tilt, and others come with a single tube. I don't think the box or load on the trailer really know anything about the framework they are sitting on. There are some myths that take on a life of their own on the internet and designing a frame with an A shape tongue seems to be one of them. It is perfectly suitable for lots of trailers but if you want the utmost in manuverability than a straight tube is best. If you can't design a trailer with a strong enough straight tongue than you should not attempt to design one.

To the OP I would widen the rails from 32 to as wide as you can go and still have enough tire clearance, I am assuming that the tires will be about flush with the box. Put a center spline and have 3 main rails. All that cantilevered tubing is overbuilt at 2 inch, 1.25 inch 14ga would be plenty. You really don't even need it if you build your box as a structural part of the trailer. Plywood is strong. I count 5 pieces of tubing in front of the box, that is beyond any kind of overkill. Look at how the frame and hitch is built on a body on frame truck or suv, it has far more stresses on it than a single axle trailer. Look at how heavy duty factory built trailers are built.

There is an old saying I learned when I was very young, " If you don't know how to tie a knot than tie a lot of them" Its modern uopdate here would be "if you don't know how to design and build a trailer, just keep cutting and welding more pieces on to it until you run out of steel"

 

[john61ct]

Yes I have no real life experience, just talking & reading a lot, so I definitely defer to the rest of you.

I would pay an engineer to sign off on safety, try to reduce weight.

Not USian of course. . .

 

[billiebob]

I'd triangulate the tongue at 30 degrees rather than 45 degrees which will add a bit of length and the steeper angle will let you turn sharper. And that is a massive advantage reversing.

Make sure the tongue is long enough to clear all the tings on the back of the tow vehicle. Doing a mock up in 2x2 wood might save head aches later.

 

[billiebob]

seems like you and user 1000arms suggest doing something like this for the tongue (and rear receiver). Think that is a great idea, thanks for the idea. Do you think having the 2" spine running hte length of the trailer is overkill?

View attachment 593910

Full length with a receiver at the trailer bumper offers a few advantages when stuck.
I do prefer cross members one piece above the main frame.

 

[billiebob]

seems chopping that A frame off is the way to go

NO, keep the A Frame and keep the short 14" extension for the hitch. Just change from 45 degrees to 60 degrees, or steeper.
You want to triangulate the hitch/tongue.

 

[CampStewart]

NO, keep the A Frame and keep the short 14" extension for the hitch. Just change from 45 degrees to 60 degrees, or steeper.
You want to triangulate the hitch/tongue.

Why, what stresses are so great that it needs the A frame. Everyone seems to think you need one but no one seems to know why. Or put it this way, why is a A frame preferable to a straight tongue made out of stronger material? Everyone seems to be recommending receiver tube for the main tongue, that is 2.5 square with 1/4 wall and I have built trailer tongues that carry far more weight than a camper box using it. Can someone please show why this is not strong enough for a trailer this size baring an accident?
How about this, if you are running a piece of receiver tubing and sleeve a piece of 2x2x1/4 inside of it for adjustability and that 2x2 extends past the plane of the front crossmember than I submit that that inner tube will strengthen that area that you want to A frame by at least 50 percent. If someone wants to argue that is still not strong enough than I will just laugh and let you guys believe in your magic A frames to really be expo ready.

OP if you do go with a long piece of 2x2 slipped inside of receiver tubing than I recommend you drill a couple of 5/8 holes on one side of that tubing and weld 1/2 inch nuts over them. Put bolts in to pinch the side of the tube to keep it from rattling around. 2 pinch bolts are better than one if you have more than a couple of feet of inner sleeve.

 

[billiebob]

Triangulation lets you build a lighter more rigid frame. Which is why manufacturers who use engineers do it.
Anything adjustable will be heavier.

 

[1000arms]

Why, what stresses are so great that it needs the A frame. Everyone seems to think you need one but no one seems to know why. Or put it this way, why is a A frame preferable to a straight tongue made out of stronger material? Everyone seems to be recommending receiver tube for the main tongue, that is 2.5 square with 1/4 wall and I have built trailer tongues that carry far more weight than a camper box using it. Can someone please show why this is not strong enough for a trailer this size baring an accident?
How about this, if you are running a piece of receiver tubing and sleeve a piece of 2x2x1/4 inside of it for adjustability and that 2x2 extends past the plane of the front crossmember than I submit that that inner tube will strengthen that area that you want to A frame by at least 50 percent. If someone wants to argue that is still not strong enough than I will just laugh and let you guys believe in your magic A frames to really be expo ready.

OP if you do go with a long piece of 2x2 slipped inside of receiver tubing than I recommend you drill a couple of 5/8 holes on one side of that tubing and weld 1/2 inch nuts over them. Put bolts in to pinch the side of the tube to keep it from rattling around. 2 pinch bolts are better than one if you have more than a couple of feet of inner sleeve.

2" square tubing, .250" wall, for a spine you can weld a receiver hitch tube to the front and the rear ...

... I suggest you use shorter receiver tubes at the front and rear. Just use 2" square-wall tubing (.250" wall) for the spine, and weld the (shorter) receiver tubes to the spine, without needing to integrate the receiver tubes in to the rest of the framing. (The photo you posted has the front receiver tube attached to more than just the spine.) ...

I've been recommending 2" square-wall tubing, .250" wall thickness, for a one piece spine/tongue with a shorter receiver tube welded on front and rear.

And:

And add the receiver at the rear too for carriers

Having a decent spine (not overkill receiver all the way)

allows you to go a bit lighter and still have good lateral strength / integrity

So, no, not everyone.

 

[CampStewart]

Triangulation lets you build a lighter more rigid frame. Which is why manufacturers who use engineers do it.
Anything adjustable will be heavier.

Full length with a receiver at the trailer bumper offers a few advantages when stuck.
I do prefer cross members one piece above the main frame.

So in one post you like building the crossmembers on top even though it is heavier and far weaker and in another you want the triangulation of an A frame because it is lighter. How much weight are you saving with the triangulation? I say the trailer will be lighter by eliminating or at least downsizing the cantilevered parts of the trailer even with the few extra pounds added by the straight adjustable tongue. If this is a thread about lightest and still strong enough we need to start completely over and discuss rectangular tubing.

From the perspective of a guy who sat in classes in my youth studying structure and design and makes his living fabricating things it is frustrating to see so much erroneous info being passed as fact by the most persistent voices in the room. I post to share firsthand knowledge, not to recommend unfounded theories.

20 pounds extra with an adjustable straight tongue means nothing on a 1000lb trailer. Being able to jacknife 90 degrees when turning around can be a godsend off road. If you don't know both of those to be facts you need to get away from the keyboard and take your trailer into some tighter spots.

 

[billiebob]

So in one post you like building the crossmembers on top even though it is heavier and far weaker and in another you want the triangulation of an A frame because it is lighter. How much weight are you saving with the triangulation? I say the trailer will be lighter by eliminating or at least downsizing the cantilevered parts of the trailer even with the few extra pounds added by the straight adjustable tongue. If this is a thread about lightest and still strong enough we need to start completely over and discuss rectangular tubing.

From the perspective of a guy who sat in classes in my youth studying structure and design and makes his living fabricating things it is frustrating to see so much erroneous info being passed as fact by the most persistent voices in the room. I post to share firsthand knowledge, not to recommend unfounded theories.

20 pounds extra with an adjustable straight tongue means nothing on a 1000lb trailer. Being able to jacknife 90 degrees when turning around can be a godsend off road. If you don't know both of those to be facts you need to get away from the keyboard and take your trailer into some tighter spots.

Ever notice some guys just like to argue ?
Go into any manufacturer and ask why they all built with A Frame Hitches and put the Cross Members on top.
You need answers, do your own research. You'll just argue if I tell you.

 

[CampStewart]

Ever notice some guys just like to argue ?
Go into any manufacturer and ask why they all built with A Frame Hitches and put the Cross Members on top.
You need answers, do your own research. You'll just argue if I tell you.

You didn't even address any of the points I made you just deflected by telling me to go talk to manufacturers to disprove my own contentions lol.

Are you saying that all manufactured trailers have A frame tongues and crossmembers on top? I would never dream of making such a statement but I would say that most manufacturers make trailers with different styles of design for different characteristics and applications.

Go ask any engineer and they will tell you that welding a tube on all four planes is far stronger than putting it on top with welds on one plane of the tubing. Ill give you a hint its called torsional rigidity. That is unless they design flex into the trailer which the crossmember on top will give them. Do you put the crossmember on top of your frame to give the frame flex,? As a fabricator and not an engineer I know my limitations and would not consider designing a structure of any kind to flex, way too many variables that are over my head.

Some trailers have crossmembers within the frame for structural rigidity and pieces on top called stringers that the decking or floor and/or walls are attached to.

Every manufacturer will tell you that an A frame is cheaper to build but they can and will build you a custom trailer with the same gvw with a straight tongue.

They will also tell you that a closed tube is prone to rust and fail without warning but that is not really germane to the discussion thus far. That is why C channel and angle iron is used a lot more. in commercial trailers Those materials are also far cheaper than tubing. From a structural standpoint most of the time a closed four sided tubing is not necessary.

Whatever a mass produced trailer manufacturer decides to do to build a trailer as quickly and cheaply as possible has very little to do with the fabrication and use of a one off custom trailer designed and built by an inexperienced untrained fabricator.

I am not arguing opinions but sharing book learned knowledge, if you want to challenge it than maybe you should show your evidence, that will not be an argument it will be proof. and many of us can learn something. I think that the guy who wants me to contact a trailer manufacturer and do research in the hope that it will prove his point and ignored the points I made in a previous post is the one arguing.

My ultimate goal is to give the OP some information to improve the design, versatility, and practicality of his trailer.

 

[Buffalobwana]

.250 wall 2x2 is about 5 1/2 lbs per foot, if I remember correctly. In this application I can’t see how it significantly strengthens anything.

Your trailer weight rests on the side of the frame where your springs attach and at the hitch. Your weak spot is the point where the box meets the tongue (in this case)

An A-frame tongue with 2x3 3/16 angle is heavy enough for most light trailer applications. Just build the A-frame like commercial trailers. Don’t go reinventing the wheel, so to speak. There is a reason trailers are built this way. Because it works

The strength of welding your A-frame under the frame of your trailer can not be overstated. This design eliminates the stress you would put on the “tongue to frame” angle. That is your weak point.

I get the desire to build one “uni-frame” so to speak, like the picture you posted on page one. It looks cool, but, it’s seriously weak at the front of the box

I get the long tongue desire. (That didn’t come out right). I made a receiver hitch on two of my trailers with an extendable tongue. It’s a piece of 2x2 .250 that slides out of a receiver hitch to extend the tongue out a few feet. Drill two holes in it. Shorten it for travel, (if you like), then extend it for camping, backing etc.

Personally I like a longer tongue all the time. Makes backing up a lot easier.

Good luck!

 

[Buffalobwana]

As for a handle, if you have a torch, get a piece of 1” ID pipe, put it in a vice and heat up a 12” piece of 3/8 cold rolled rod at the 3” mark. Stick it in the pipe and bend it to 90 degrees. (Let it cool) then do the other side at 3”. There is a handle. Weld it to the side of your frame. Simple, light and easy.

 

[1000arms]

.250 wall 2x2 is about 5 1/2 lbs per foot, if I remember correctly. In this application I can’t see how it significantly strengthens anything.

Your trailer weight rests on the side of the frame where your springs attach. Not on a spine. So, unless you plan on pulling a 16’ trailer behind this trailer, ditch the full spine. Wasted money, wasted weight.

2x3 3/16 angle is heavy enough for most light trailer applications. Just build the A-frame like commercial trailers. Don’t go reinventing the wheel, so to speak. There is a reason trailers are built this way. Because it works.

I get the long tongue desire. (That didn’t come out right). I made a receiver hitch on two of my trailers with an extendable tongue. It’s a piece of 2x2 .250 that slides out of a receiver hitch to extend the tongue out a few feet. Drill two holes in it. Shorten it for travel, (if you like), then extend it for camping, backing etc.

Personally I like a longer tongue all the time. Makes backing up a lot easier.

Good luck!

Yes, approximately 5.5 lbs/foot, you do remember correctly.

The spine allows for recovery, from the rear, of both trailer and light tow vehicle, to a certain point. If more than a bit of assistance is needed, then separate the two, recover the trailer, and then the tow vehicle.

The spine also, when "hung" from the frame, reduces the amount of cutting, aligning, tacking, and welding needed to fabricate the frame. Having the thicker wall helps with the strength of the spine/rest-of-frame connection and eliminates the need to use a thicker-walled separate piece for the tongue, for a trailer of this weight/size.

2" square-wall tubing, .120" wall thickness, is about 3 lbs/foot. As we both have mentioned, the .250" wall is about 5.5 lbs/foot. A 12 foot piece is about 66 pounds, and replaces some .120" wall thickness tubing, so it will add less than 66 pounds to the total weight, but offers the benefits mentioned above.