POD: Custom camper - design stage

[Heifer Boy]

This didn't clearly answer to myself in regards to a path forward for a layup schedule but I have some things I can consider as I look at my design, surface area, weight/cost of each ply.

Nice testing regime :victory:

One thing that is a little worrying is the spur fractures when just using the foam. Admitedly it would be a big hit to make this happen and I can't see this happening outside of an accident but on a finished camper a spur could be hidden under the paint and missed during a repair. The 1/8 ply seemed to stop this. Would using the ply with a lighter thickness of foam achieve the same results? How would that effect cost/weight/insulation? How much extra work would it be for the outside possibility of a small high velocity hit?

I thought about all the same after my tests and coudn't really come up with a scenario when the camper could take a hit like that at speed. Maybe a bump trying to squeeze into a camp spot or a tree branch dropping on you at night but not while driving down the highway.

I think the 'jumping up and down' test is more relavant to test overall rigidity and strength of the panels and joints. Your examples passed with flying colours. Good stuff.

I like your other plans and thoughts too. Big campers like this take a whole lot of planning to get right and there are so many options. I'm watching keenly.

@billhilly - nice examples.

 

[pods8]

So lots to sort and plan huh.
You've seen this lift system - http://hydromechusa.com/ ? Don't know anything about their quality, how the price compares to other options, but it certainly is a pretty clean sort of a deal.

Yes I have and I'm talking to them. That website though is misleading, that isn't the actual product and that website was put up by someone not associated with the company (something about a guy wanting to become a partner or something I was told). The actual company has no control of the content on that site. I've seen a picture of the actual pump assembly they do make but it looks nothing like the one on the page. It does appear to be a nice little package.

The problem so far is the lack of an answer if they would sell me a unit and for how much, they currently only deal with camper OEMs. Still pursuing with them and trying to see about at least getting a pump unit if nothing else from them. I don't need the double action lifts but either they or I could rework them since the main lifting cylinder is a 26" stroke and that is fine of my needs.

So lots to sort and plan huh.
One thing to remember is ordinary polystyrene (white/soft) reacts with electical wire coatings and will eventually 'rot' the insulation off. Not sure how this extruded polystyrene would react but possibly in a similar way so all wiring would need to be ducted.

I was not aware of that, very good to know.

Nice testing regime :victory:

One thing that is a little worrying is the spur fractures when just using the foam. Admitedly it would be a big hit to make this happen and I can't see this happening outside of an accident but on a finished camper a spur could be hidden under the paint and missed during a repair. The 1/8 ply seemed to stop this. Would using the ply with a lighter thickness of foam achieve the same results? How would that effect cost/weight/insulation? How much extra work would it be for the outside possibility of a small high velocity hit?


I like your other plans and thoughts too. Big campers like this take a whole lot of planning to get right and there are so many options. I'm watching keenly.

@billhilly - nice examples.

The spurs are just some resin cracking but are quite sturdy still so not as worrisome as you might thing. I'd say if the cracks carried through into the paint then you'd know you have an issue. Just my unscientific thoughts.

1/8" plywood is about 2-3times as heavy as a ply of glass so a layup that was 1/8" plywood with 2 plys of glass would weight 1.33 to 1.66 times as much as 3 plys of glass. Cost would be about the same. Foam thickness I want to use is more a function of fitting in extra insulation.

Looking at the costs of the panels and time to lay them up I've also decided to check into prefabbed core panels to see where the cost comparison weighs out there. Might end up being worth considering buying flat panels and make better use of my time assembling, glassing up corners, cutting in windows/doors, etc. We will see.

There is definitely a lot of things that need to be ironed out that are taken for granted in a final product. While I'm stewing on other things I think I might do a detailed model of all the tanks, batteries, etc. would be inside the cabinets and such to check that one off the list.

 

[ersatzknarf]

Hi Pods,

That is a very logical consideration.
Are pre-fabbed core panels commonly available ?
With all the interest in the Nida-Core like materials, I am a bit lost on what is out there...
Considering field repairs, etc., the foam core / fiberglass construction seems to make a lot of sense for travelling, compared to the pultruded PP core materials.

(by the way, how about air-powered cylinders or linear electric motors for lifting the roof ?)

<snip>

Looking at the costs of the panels and time to lay them up I've also decided to check into prefabbed core panels to see where the cost comparison weighs out there. Might end up being worth considering buying flat panels and make better use of my time assembling, glassing up corners, cutting in windows/doors, etc. We will see.

<snip>

 

[pods8]

Hi Pods,

That is a very logical consideration.
Are pre-fabbed core panels commonly available ?
With all the interest in the Nida-Core like materials, I am a bit lost on what is out there...
Considering field repairs, etc., the foam core / fiberglass construction seems to make a lot of sense for travelling, compared to the pultruded PP core materials.

(by the way, how about air-powered cylinders or linear electric motors for lifting the roof ?)

The thought just crossed my mind a few days ago so I really don't know much at this point. Nothing really appears commonly available but if you're building a whole camper I think you can scrounge up an order, I just don't know how much a premium you pay for a smaller order. Biggest thing to likely figure out is what sizes/style are more of a common run for the companies and see if you can work around that to keep the cost down.

If I went with a prefabbed panel I'd be looking for something that was compatible with epoxy and fiberglass. If so you could do repairs with scraps from the build or still be able to use foam & thickened epoxy to repair core pieces. Then used fiberglass to repair the skin. I've got more research/looking to do to figure out what options there are.

Here are the lift thoughts that have crossed my mind or been brought up so far:
Hydraulic - most preferable in my mind if I can get a synchronized system for a reasonable cost. You only have to deal with vertical lifting, the cylinder bores are smaller since they work at higher pressures, incompressible fluid so as long as they are fed the same amount there isn't any issues with different lift rates.

Pneumatics - Larger cylinders than hydraulics and then since gas is compressible you have issues trying to get a balanced lift.

Linear actuators - different loads affect their rate of lift as well, you can operated them off one master switch and then have individual correction switches for each one so you can jog them back into sync as needed. However that seems like a lot of hassle to have to do over and over again, and the potential to bind things up when you're tired/rushed.

Screw jacks - simple & reliable, still has a vertical lift, but would take gear boxes and drive shafts to couple everything together to get a sycn lift.

Scissor lifts - Have to deal with out of plane (ie not vertical) forces, have to accommodate for the linkage and movement of the linkage in the camper area.

Traditional pop-up telescoping cable lifts - I can't really find any of these for sale as a stand alone item to see where the price point is on them. Downside is you need to route the cables and rely on them not to snap over the long haul.

Gas springs - Would be hard to get a sycn lift out of them, I wouldn't trust them to support a snow load or something of that nature but supports could be snapped into place once the roof is up to support stuff like that. However you need to get the load rating right and there isn't leeway for adapting to load changes (ie snow of the roof). Again hard to sycn.

sarconcepts cable method could sycn up most lift systems but I'm not too keen on routing all the cabling. Ideally synchronized hydraulics just take a single tube routed to each cylinder, much more appealing if the cost point is there.

 

[ersatzknarf]

Hi Pods,
Thank you for the detailed response.
I think the foam cored FRP panels of interest are used for refrigerated trucks in Europe, but I have not found anything here, yet. . . (just recalled hearing about something called, Kemlite (sp?), but nothing more on details)
As for the lifting mechanism, I see your point. The thought of a fluid leak is the only thing that is off-putting...

 

[pods8]

Hi Pods,
The thought of a fluid leak is the only thing that is off-putting...

Leaks are only going to occur at fittings or orings within the cylinders in most cases. Fluid quantities are low as well so shouldn't be too much concern. So while designing make sure to leave access to the fittings and the ability to yank a cylinder if needed for service. Also a little containment perimeter around the cylinder and pump would be cheap insurance to catch any leaks that did arise and limit the cleanup.

Most of the complaints I've seen on hydraulic lifts are old alaskan campers and such. In reality they just need an oring swap and there would be no issue. If they were easily done then you wouldn't see people letting things like that go and making a mess.

 

[ersatzknarf]

It looks like you have considered using hydraulics well and so it should work out for you.


By the way, here is that Kemlite link : http://www.cranecomposites.com/

I have looked at their site a few times, now that I recall it, but haven't really made heads or tails of their offerings, but perhaps the site is more geared to attract inquiries from manufacturers to use their products. I will have to look into it further. If they offer a foam core / FRP board in large sizes, they might be a consideration...

 

[Greg]

Pods8,

Have not contacted these people about their panels. The photo with the two people standing on a fiberglass skinned panel looked interesting. Looks like they use an internal grid connecting the inner and outer skins.

http://www.superhoneycomb.com/product_fiberglass.html

 

[pods8]

Thanks for the links guys, I'll dig into them. The super honey comb place is only located 2 hrs from me so depending on their offerings it would allow some face to face on the product and avoid shipping. We'll see what I dig up and pricing (which could be painful)...

 

[pods8]

Just a little follow up note on the testing. It dawned on me in my enthusiasm to beat up those samples I probably didn't let them cure long enough (epoxy develops a good chunk of strength early but it takes a while longer to build the rest and it is also a little more brittle early on). Anyways now that its been over a week I smacked the #2 test part (with 3 plys) again in the areas that hadn't already had a punch through failure and didn't have any hits bust through. There was some cracking but no complete failures, so there is an improvement. I'm not going to bother with pictures since all the damage areas are intertwined now. I may make some more test pieces and if so I'll see how the clean pieces react after a longer cure.

 

[phird05]

Pods, when are you going to start this build? I'm sure I am not the only one here that is anxious to see the progress! I just yanked my camper out of the garage for the season and it got me wondering about your build. I have no time or desire to build a camper, so I rely on everyone else to see good results.

Paul

 

[pods8]

I haven't quite found my clear path forward yet but if I'm going to do this thing I'd want to start within a month or so. I've got some inquiries out about some prefab panels that I'm waiting for pricing/lead time on to see which way to go there as well.

If I'd be doing the panel layup I need to have a chat with the little lady to make sure our expectations on required time to get this done in a reasonable fashion are aligned. No need to turn the camper intended to accommodate the family better into a family wedge. Gotta be realistic on that front, which is why I've been doing as much front end research/planning as possible.

That said I'm antsy too...

 

[ersatzknarf]

We're antsy, too ! :sombrero:

Pre-fab panels will be interesting to hear about whether that is a viable means...

Since those "G-Wagen"-style ambu boxes don't seem to grow on trees around here, making one using your method has a lot of appeal - that and we could configure it exactly as needed :ylsmoke:

Sure hope that this all works out for you, regardless ! ! ! :coffeedrink:

 

[pods8]

Things are looking up on the hydraulics front. A pop-up truck camper company has recently contacted them about getting some units setup for their rigs which means there is an larger manufacturing push to make the couple adjustments towards the design I needed (a straight cylinder lift as opposed to the double action lift). So it sounds positive about being able to obtain something from them now. Nothing in stone yet, I'm supposed to call back in a couple weeks and ideally they should have some units available and we'll see if we can knock out a deal.

In the meantime I know the dimensions for the drive unit so I can delegate an area in planning and I think it should work nicely as sketched below.

Reference back to the original sketch in terms of cabinet layout:

Here is where I think I'd stick all the utilities into that layout. Taking into account the gas tank under the truck it should decently balance out side to side weight and keeps all the major camper weight low/forward. (The 50# fridge would be above the water tank/batteries as noted in the original layout. I'll move the stove above the fridge as well, not really a weight consideration there but just reflecting my current thought since its not properly depicted above.)

 

[teleturns]

PODS

Have you done any research about Polystyrene foam board in relation to off gassing? I searched around the internet, but I didn't find much. I am wondering if there are any poisonous toxins that could be off gassed by the Polystyrene. I wouldn't want to sleep in a camper full of harmful gas fumes.

It's just a thought. I plan on insulating my FWC with Polystyrene foam board and am interested in what you think about off gassing.

Thanks
Tyler