DIY camper box construction- what sizes/wall thickness steel or alu have you used?

Reworked LMTV

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I am fully aware that this thread started as a metal approach to an RV. I think this video provides valuable perspective. I have seen thousands American and European builds. Forest builds one a year and sells them for about $69k. It is one of the nicest, practical builds that I have seen. It is simple, elegant, and has a lot of windows real estate. You don't feel so boxed in. I met him and toured his rig at the East Overlanding Expo. He uses a composite of wood, foam, and epoxy. He uses the West System I believe. They make large boats with it. I have used it. It is unbelievably strong if you know what you are doing.

 

B-Dog

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Just a couple of my thoughts. I agree composite is likely the best overall however as stated above, might not be the best for your low(er) budget DIY builder. For what it's worth, I'm planning on building a steel tube frame box from primarily 2x2. I'll skin the box with FRP panels.

Aluminum transfers heat very well. If you make the box from aluminum, it will xfer the heat from the outside to the inside during the summer and xfer heat from the inside to the outside during the winter.

Careful how you attach dissimilar materials. Different materials expand and contract at different rates. Someone mentioned earlier something about sikaflex to adhere FRP to metal. I don't know how that will work (no experience) but I do think you could run into troubles if you use rivets or screws to fasten plastic to metal or steel to aluminum. Just be mindful of expansion contraction....
 

Reworked LMTV

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Just a couple of my thoughts. I agree composite is likely the best overall however as stated above, might not be the best for your low(er) budget DIY builder. For what it's worth, I'm planning on building a steel tube frame box from primarily 2x2. I'll skin the box with FRP panels.

Aluminum transfers heat very well. If you make the box from aluminum, it will xfer the heat from the outside to the inside during the summer and xfer heat from the inside to the outside during the winter.

Careful how you attach dissimilar materials. Different materials expand and contract at different rates. Someone mentioned earlier something about sikaflex to adhere FRP to metal. I don't know how that will work (no experience) but I do think you could run into troubles if you use rivets or screws to fasten plastic to metal or steel to aluminum. Just be mindful of expansion contraction....
Styromax of Australia uses rivets and Sikaflex. https://styromax.com.au
 
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Third From Texas

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All the above are valid perspectives, but not relevant to the info I seek (not looking to start a debate over which construction method is best). My objective is to construct an RV which takes advantage of the platform to get my wife and I wherever we want to go with a certain level of hospitality. To put this more in context, we have a 1088 already. I want to do this to it (roughly speaking):

View attachment 785293

The entry may get pushed back up to floor level but it is what I would do if cost and manufacturability were no object. Looking at some of composite places, they are still big bucks once you start adding everything up. I am a DIY type of person, happy to experience the build side of things along with the usage. I can string steel together. I have little experience with composites so my preference would be frame it up.

If there was a place for me to get panels to fit into a skeleton frame based on the above sketch, I'd be all ears. Right now, my known quantity is the steel route.

ReworkedLMTV - I would be interested in knowing what steel components will be used for the skeleton on your concept. Got a camper build thread going yet?

Chris
Nice design.

I don't see why you couldn't do a full-steel skeleton of the entire hab. Then have someone like Total Composites build you the skin. Since the panels would not be under "structural load", I would suspect that a much thinner panel could be used. Sikaflex those buggers on leave secure points as needed.

I'm sure someone, somewhere out there has done it (a hybrid of composite over steel frame). It *could* even be less expensive than 100% composite, no thermal bridging issues (I can attest to what a bugger that is after a few nights in the M1079 at sub-freezing), allows for insulation (the thickness of the frame), and provides a mounting point for internal walls (if I see another seamless, gloss white, sterile RV interior on an overland build I will throw up).

:)
 

Nomadic

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I've been researching this for 3 years. My design has changed a zillion times. Mostly after talking to people that I would consider experts. If you have not attended the Overlanding Expo, please do so. Ask a lot of questions. Tour the Earthroamers, GXV's, the DIY builds, and investigate your assumptions. Film everything. One size does not fit all. Someone nearing retirement will not want the same vehicle as a highly testosterone'd 20 year old looking to not work and live in their RV after they graduate from college. What is right for you, may not be right for others. Drives me crazy when people don't consider a user's needs, abilities, and finances, and blast off comments about the RV that they have never built or have.

Total composites wants $15k for a boring box with no windows nor doors.

PM me if you want more info.
I looked into the Total composits kit. The insulation is attractive. But the pieces are glued together and can't handle the flex that occurs off-road.
 

Reworked LMTV

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I looked into the Total composits kit. The insulation is attractive. But the pieces are glued together and can't handle the flex that occurs off-road.
[/QU
I'm not sure where you are getting your info. from, but once they are glued, they are brutes. Most designs, even some steel ones, have a pivoting frame to prevent excess torsion.
 

Third From Texas

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Anything that you build is going to need a sub-frame that allows for flex. Especially on the scale you are planning.

Even the little 12' box the military uses on the M1079 rides on captured springs on each side in the back to allow for flex.

But yeah, composites especially due to the rigidity. Not so much due to the adhesive process.
 

Reworked LMTV

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Who did you talk to at TC? Why would they have a full line of "expedition" boxes??
 
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ramdough

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From the company itself.
Their boxes require a torsion free subframe.

They are limited by your subframe and what you want to hang off them. For example, they do not work well with large rear overhangs and spare tire weight. They prefer a flat reinforced back wall if you plan to hang the tire on the panels.


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ramdough

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Hi all,

I posted this on ExPo forum as well. I am pondering options for building an expedition camper build and am curious to hear from any home builders who have used steel to build their habitation box. What sizes and thicknesses did you use?

Chassis will be an M1088. Would be interested in knowing the subframe selection and results if you're willing to share that too.

My current thoughts make me think I am seriously over-spec'ing it. If you have built one, would you change what you've done if you were to do it again?

Thanks in advance,
Chris
My plan:

Steel frame. The bottom will be a bit beefy with captive springs holding the box to the truck frame. Wall framing will be max 2” tube. Other places will be angle.

Insulation will be 3” xps foam. So, no exposed steel.

Deciding still on mounting of interior. May run small offset steel tabs or wood battens to reduce conduction. Have not decided yet.

I will combat condensation by having no propane on board. Constant ventilation from outside. Dehumidifier running. And as few thermal bridges as I can.

Plus, it does not get cold often where I live. Most concern would be on trips.


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Reworked LMTV

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My plan:

Steel frame. The bottom will be a bit beefy with captive springs holding the box to the truck frame. Wall framing will be max 2” tube. Other places will be angle.

Insulation will be 3” xps foam. So, no exposed steel.

Deciding still on mounting of interior. May run small offset steel tabs or wood battens to reduce conduction. Have not decided yet.

I will combat condensation by having no propane on board. Constant ventilation from outside. Dehumidifier running. And as few thermal bridges as I can.

Plus, it does not get cold often where I live. Most concern would be on trips.


Sent from my iPhone using Tapatalk
[/QUOT
My plan:

Steel frame. The bottom will be a bit beefy with captive springs holding the box to the truck frame. Wall framing will be max 2” tube. Other places will be angle.

Insulation will be 3” xps foam. So, no exposed steel.

Deciding still on mounting of interior. May run small offset steel tabs or wood battens to reduce conduction. Have not decided yet.

I will combat condensation by having no propane on board. Constant ventilation from outside. Dehumidifier running. And as few thermal bridges as I can.

Plus, it does not get cold often where I live. Most concern would be on trips.


Sent from my iPhone using Tapatalk
I'm not sure that I understand the propane comment. Certainly propane combustion, or pretty much any combustion creates H2O, but this should be vented. Second, just human perspiration and cooking and showering will overwhelm a camper with moisture. Copy the professional builds. You will save yourself a lot of frustration.
 
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Nomadic

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Their boxes require a torsion free subframe.

They are limited by your subframe and what you want to hang off them. For example, they do not work well with large rear overhangs and spare tire weight. They prefer a flat reinforced back wall if you plan to hang the tire on the panels.


Sent from my iPhone using Tapatalk
Right, torsion free is what it needs. But finding a platform that doesn't flex when off-road and crossing a washout might be hard. I am in no way shape or form saying it can't be done. Allowing some flex is what I want to have a margin of error or to have the box itself add rigidity.
 

ramdough

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Right, torsion free is what it needs. But finding a platform that doesn't flex when off-road and crossing a washout might be hard. I am in no way shape or form saying it can't be done. Allowing some flex is what I want to have a margin of error or to have the box itself add rigidity.
The best thing is to allow the vehicle frame and the camper subframe move separately. There are hundreds of pages of that info on expo.

You do not want your camper to stiffen your truck. That is a recipe for breaking something.


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Nomadic

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The best thing is to allow the vehicle frame and the camper subframe move separately. There are hundreds of pages of that info on expo.

You do not want your camper to stiffen your truck. That is a recipe for breaking something.


Sent from my iPhone using Tapatalk
I think your right about the camper stiffening the truck bed. As far as having the truck frame flex in isolation to the camper, do you know of any successful (demonstrated) builds on expo that you could link to?

I had been following that topic there somewhat and saw builds, but no results other than driving off-road on non-technical ground. There was a Fuso build where a guy broke his frame. A FMTV with a commercial box fitted & customized.
I think the most impressive demonstration was with a stock M109 Shop Van. It was articulating massively in a YT video. So far, I haven't seen anyone come close to that level of off-road worthiness having a camper on back. I'm sure they are out there.
 

ramdough

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I think your right about the camper stiffening the truck bed. As far as having the truck frame flex in isolation to the camper, do you know of any successful (demonstrated) builds on expo that you could link to?

I had been following that topic there somewhat and saw builds, but no results other than driving off-road on non-technical ground. There was a Fuso build where a guy broke his frame. A FMTV with a commercial box fitted & customized.
I think the most impressive demonstration was with a stock M109 Shop Van. It was articulating massively in a YT video. So far, I haven't seen anyone come close to that level of off-road worthiness having a camper on back. I'm sure they are out there.
I would buy the book from Ulrich Dolde (spelling?) on diy camper building.

He explains the different types of methods for dealing with subframe isolation.

I am building on an M1083, and plan to use rail on rail with springs for my truck. That was not an easy decision, but I deal good about that choice. I have seen 4 point diamond bushing isolation on my truck as well. The three point designs I usually see on shorter trucks.

If you get on YouTube and look at Unicat’s videos you can see some extreme flexing where the box is twisted independent of the cab.

The isolation designs are pretty well standard, the trick is to not put concentrated loads on your frame in a way that damages your frame. To me, that is the real trick. Rail on rail designs are just easier not to screw up and on my truck the flex is not excessive like a Unimog which requires at least a three point. Hope that helps.


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