POD: Custom camper - design stage

[Home Skillet]

Some of the folks on here are using a similar one by I haven't called the manufacturer with questions at this point.

Ya I looked at the Firgellis and acutally talked to them for a awhile too. There really isn't a good solution for the speed/weight problem other than what you have mentioned.
I am thinking I will use a remote device to control the lift and can then do visual/manual adjusting on rise and lower. Not eligant, but will work per the manufacturer. I just don't know how else to do it. I have the same issue with the cabover portion being the duty for the front 2 lifts too.

Home Skillet

 

[pods8]

Ya I looked at the Firgellis and acutally talked to them for a awhile too. There really isn't a good solution for the speed/weight problem other than what you have mentioned.
I am thinking I will use a remote device to control the lift and can then do visual/manual adjusting on rise and lower. Not eligant, but will work per the manufacturer. I just don't know how else to do it. I have the same issue with the cabover portion being the duty for the front 2 lifts too.

Home Skillet

What swayed you to progressive by the way? The firgellis are $5 cheaper and have a better duty rating.

Although there is a cost involved as long as you're not putting stuff on and off the roof I'd think once dialed in with controllers then actuators would then be good to go. I'm pretty damn rusty on my EE but when I get down the road perhaps I'll do some research to see if I could just build a 4 actuator controller based on the PWM the manufacturer uses.

 

[MrBeast]

Man really interesting thread, just skimmed through the whole thing, learned quite a bit.

 

[pods8]

Okay more design thoughts now that I need to start turning my attention to building the lower wall cores. Two issues to iron out, the water fill and external hatches.

Water fill: To do an external gravity drain that doesn't require lifting the top up I'd need to do it in the front wall in the little bit of space not blocked by the cab. This doesn't seem ideal. I'm not really interested in having to lift the roof to access a gravity hatch either. I could use a "city water hookup" to fill the tank but if I'm not around pressurized water that is no good. So I'm sorta thinking an access hatch lower down (or just inside the door way) with a small pump & tubing might be the way to go. I'd just open up this hatch, drop the tubing into my water container and pump it into the water tank (perk would be being able to leave the tank on the ground). There might be the possibility of valving out the normal pump for double duty depending on how I finally lay things out but either way a second pump isn't a high dollar item. For a backup I might include a capped gravity fill tube inside the camper.

External hatches: This is in regards to the areas under the dinette seats. How much value do people see in being able to get into one (or both) of those areas from the exterior of the camper verse just lifting the seats up inside? I see some value if someone (or gear) is on the seats in not having to have them move. But I don't know if its worth bothering with a hatch. Hatch adds build complexity and is just another thermal and moisture infiltration point that would need to be sealed off.

Thoughts from field experience?

 

[DEnd]

I'm moving our discussion over here from Home Skillet's thread, because I think it fits better. So to recap:

Secondly did you consider doing dove tail corners? It seems to me that the 90 degree corners are the "weak" point in the design, but then agian I'm not at all familiar with foam and fiber composite construction techniques. It just seems to me, comming from a wood working background that would be the strongest way to join the pieces. Though I understand that it could be a bit overkill.

The core really isn't intended to be load bearing in the manner you are thinking. The skins take all those loads. The core is intended to keep the skins from buckling and in relation to each other. Sandwich construction is basically a big I beam except the center is full of foam instead of a strip of material (if that makes sense) but accomplishes the same task.

I was more thinking it would give the greatest binding area at the corner for each peice of foam to the fiber.

I guess I'm not following what you're talking about. In his build be built the whole core structure out of foam and then wrapped his carbon plys over it so they are one continuous skin over the corner. Where do the dovetails come into play in your mind, I'm assuming you're talking about jointing the core pieces together?

Right just the core peices. To me it allows the stress of possible core seperation to be spread over both sides of the 90 instead of just one, if that makes any sense. To me the joint itself is where there may be possible weakness in the design (where nonimpact caused delamination may be most likely to occur). While a dove tailed or finger jointed corner would increase the actual size of the join area by about 2-3 times, having it spread over both sides (basically doubling or so the surface area where the join contacts the fiber) would increase it's strength, by spreading out the forces that may cause delamination over a larger area (more fibers over the total join).

And to expound a bit more notice on your picture:

the damage to hit 1D is largely on the join side of the corner, using a dove tail or finger joint method I would think that the damage could be more equally distributed, resulting in a smaller area of damage. but I could be completely wrong though... It wouldn't be the first time. and of course the damage may tend to be on that side if that's where the forces mostly landed too...

 

[windsock]

Hi pods8,

Some thoughts...

Your pumping idea above sounds good. However, if wanting to go with gravity, one method I had thought of requires a 'snorkel-like' pipe to your water tank. The inlet (that goes through the wall of the camper base) to the tank is low enough to be below the top of the camper in the lowered position and the top of the 'snorkel' is high enough to ensure the level of the full tank wouldn't overflow. Hard to describe well really but I hope I have done that. Strength of the freestanding pipe would be the weakness. You may need some bracing built into the top portion of the camper to protect it from vibration while travelling.

As for external hatches. The only need I can see from my own experience would be access for recovery gear while driving rough country. I guess we all see a lot of pictures of others campers where this and that wonderful camp-enhancing equipment slides/rolls/is accessed out of hatches left right and centre. In previous trucks and campers all those years ago I have always lived with the weather-tightness concept first. All very well designing for vertical rain while in camp-mode but in a camper the rain is 3D at times as well while travelling with all the inherent internal pressure zones and this can be a problem. It is all a trade-off. I say weather-tight first, convenience of access second. If you can do the latter while ensuring the former, why not.

Dovetailing joints in foam? While I see clear benefit in wood, where the joint is to be stand-alone for strength, I don't see any benefit for foam when the strength of the join is not only the joint but also the enveloping skin of glass over cloth. Butt-joints on foam and then glassing over a cloth and filleting inside I would imagine to be ample for this type of construction. I too could be wrong...

 

[pods8]

For starters when I glue foam together with a microslurry the joint in actually stronger than the other core foam.

In regards to a corner again the foam doesn't get the loads you are thinking. It sees compression and sheer at the skins. The skins take the load. The core just has to hold them in relation to each other, that is why honey comb cores with open spaces still work. So even though the cores don’t see the loads you are thinking the joint in this case is stronger than the rest of the foam (also the inside corner gets a fillet to relieve the stress concentration, the outside corner which the joint isn't on is also radiused).

In that picture that one side was just loaded more. I did that by laying a board over the piece with the corner pointing up and jumping on it, one side of the board was touching the ground and that was the side.

 

[DEnd]

I get that the foam doesn't see hardly any loading, I was more concerned that at the join, due to a possible higher resin content in that area, the join might be weaker than the rest of the structure. As well I was concerned that the fibers might not be as well bonded at the join itself as the rest of the structure.

Thinking about it though I think that due to the difficulty of getting dove tails and finger joints really tight (a bit of a problem I've had in wood working and with my polystyrene bee hives) adding an extra layer or two of fiber over the join would probably be the simpliest and probably better solution to my percieved "problem." (if it is even one).

 

[pods8]

I get that the foam doesn't see hardly any loading, I was more concerned that at the join, due to a possible higher resin content in that area, the join might be weaker than the rest of the structure. As well I was concerned that the fibers might not be as well bonded at the join itself as the rest of the structure.

Thinking about it though I think that due to the difficulty of getting dove tails and finger joints really tight (a bit of a problem I've had in wood working and with my polystyrene bee hives) adding an extra layer or two of fiber over the join would probably be the simpliest and probably better solution to my percieved "problem." (if it is even one).

The resin is stronger than the foam though, I think you are giving the foam more credit for strength than it really has. If you glue the edge of a piece of foam flat on a piece of wood w/o any fillets and then pull on it it will likely fracture above the glue line still (leaving foam on the wood). If you have fillets you can guarantee it will fracture in the foam and not the bond. Since the joint is stronger than the rest of the foam core you have no worries about that causing the core to fail.

Then since the core isn't loaded in a manner you are thinking it really doesn't even matter.

Below is a crude paint sketch of how I'm assembling my corners since I'm building my panels and doing the bulk glass work with them flat. Pink is the foam core, black is the bulk glass plys, red is the thickened epoxy in the joint and making up the interior fillet, grey is the subsequent glass plys to really strengthen up the corner.

Edit: Technically I'll have some plywood strips as noted by the brown in the picture below but they aren't there for core strength. I'm using them to make trimming the edges of the layups easier and also to have something to screw into to hold the panels together during fitup and then while the epoxy sets up when I finally assemble things.

 

[pods8]

Windsock,

Not really following the snorkel idea entirely. I am swaying pack towards thinking about a gravity fill potentially in that front wall though.

On external access right now I'm thinking main door (duh), a propane hatch (but this compartment would be sealed from the main rig so not as much worry), and maybe a hatch on the back to access into one of the dinette seat storage areas (I think I'll frame for it now and can either opt to glass it over or leave it open down the line here, even if I do glass it over I can cut it open later...). I've found a RV takeoff place with clamp in style hatches for ~$10ea so rather than bother trying to fab up my own I might just pick up one of those for the propane and one for the back hatch. Not a big deal if I scrap the back hatch idea then.

Now I just need to figure out what size propane hatch... I'm pondering reworking the whole utility layout. Also maybe only doing a single propane tank in the camper (can probably carry a second tank under the flatbed if needed to swap out).

 

[windsock]

Windsock,

Not really following the snorkel idea entirely. I am swaying pack towards thinking about a gravity fill potentially in that front wall though.

Sorry about an unclear description. Recovering from the flu right now so not feeling so lucid... picture x 1000 words et al... this would be through the front wall. Hope it is clearer than previous effort. All the best.

 

[pods8]

Sorry about an unclear description. Recovering from the flu right now so not feeling so lucid... picture x 1000 words et al... this would be through the front wall. Hope it is clearer than previous effort. All the best.

Actually the front wall doesn't have any overlapping action (its under the cabover) so a normal fill hatch there is just fine. I'm just pondering if I want one there in the smaller front space not blocked by the truck cab.

However it dawned on me that the first ~8" or so of roof lift I still won't have exposed the camper cab over interior so I could lift the roof a bit to expose a side water fill if needed I suppose. Not ideal since the roof does need to get lifted some but not the end of the world either. My main concern with having to lift the roof before would be needing to hop up into the camper and flip the cabover walls into place so things were closed up while the roof was up.

 

[pods8]

Okay decided to do some reshuffling in utility layout. Would love any input anyone out there has asap as I'll be likely framing in cutouts for this stuff this coming weekend.

In the sketch below the yellow represents the overall cabinet outlines. Red is the visible outlines of the utility blocks w/o regard to the cabinet lines overlaid. Blue is the hidden lines in the sketch, hopefully that helps visually make things stand out in the iso sketch?

I've scaled back to a single 20lb propane tank in the camper and figure I'll carry a spare if needed elsewhere. On the driver side will be the fridge, battery/electronics compartment, and also a compartment that could either fit a 7gal water cube/a portable toilet/or misc storage. Main water tank is along the front, partially offset to the driver side. There will be a 4-6" gap between the driverside wall and that tank which will house the pump, drain/fill lines, etc. I plan to add a small utility access hatch (I've seen stuff in the 4"-6" range) so the pump can be serviced if needed. Moving back along the drivers wall will be a 17"x14" hatch into the propane compartment, behind the propane compartment will be the heater with it's vent. In front of the propane compartment will be the grey water jug which can be removed out the front of the cabinet to dump.

 

[Billhilly]

Can't fault it. With the space you have it covers all the basics very well. Power next to fridge, propane next to heater. Option for porti potty, weight well forward etc, etc.
If you made a full extension slide out pantry deal above the water tank, against the front wall, it would slide out over your water tank/step and use all available space in that corner too.

 

[pods8]

If you made a full extension slide out pantry deal above the water tank, against the front wall, it would slide out over your water tank/step and use all available space in that corner too.

Yes the remainder of the cabinet will be populated with drawers and doors to utilize up the space. There will be a little dead space between the driver wall and water tank where the pump will be not too extensive, it would be hard to work around the plumbing there anyways.