POD: Homebuilt foam core fiberglass skin pop-up camper build thread

[pods8]

Pardon me for feeding the hijck, but I've been wondering if an old waterbed matress would be good for weighting a large panel. Whata ya think?

If you wanted to deal with it I'd think it okay for a bit of even pressure but pumping water in and out, etc. doesn't sound fun. If you're barking up that realm where you want a good solid constant pressure a vacuum pump would likely be much easier. Say a water bed mattress is 6" thick? If so that would get you ~1psi of pressure. Where as a vacuum pump pulling 27inHg would deliver ~13psi. It only takes ~2inHg of vacuum to deliver the same pressure as 6" of water. So if you're got the need for it perhaps check into that a bit more over a water bed mattress.

I didn't really see the need for it in this application in the way I laid down the epoxy and stapled the plys down. Since I had the pavers handy I tossed them on for good measure as well though. Don't get me wrong if I had a decent sized vacuum pump sitting around already I would have likely tried throwing together a vacuum bag out of thick visqueen and tape but I wasn't going to go out of my way for it.

 

[Birder]

Ahhhh, but you could sleep on the job then Pods8

Cool build

 

[Home Skillet]

Looking really good Pods. I really like the imbedded wood. The attention to detail now will really pay off later.

I don't think vac bagging is a very good option here. Its not nessecary and adds a ton of extra work and effort for essentially the same outcome. What you are doing will work fine, probably even better than what I did and mine is good enough.

Keep it up!

Home Skillet

 

[Kilroy]

Really interesting and well written build. Look forward to watching your progress. Thanks

 

[pods8]

Update 4 (35hrs in): Did some cleaning/rearranging in the garage and used up some of the stacked materials so I'd free'd up space to move around a bit more. The overhanging 1/8" ply on the floor was trimmed, there were some gaps along the edge between the core and plywood so I filled those in with a thickened epoxy mixture and will need to resand/smooth all that out.

The floor creates a nice work platform in the meantime as well. I quickly did the rough outline of most of the lower walls and cut/fit the chunks of foam in the sections that aren't question marks. The other areas have windows/heater vents/propane hatch, etc. that I need final dimensions on so I can fit the wood/foam accordingly. Once I know that I'll glue the cores all together and fair them out to prep them for glassing (they are just friction fit, taped/clamped together right now). But it is good to see some shape coming together.

Sections mocked up together

Broken back down for the day

 

[Billhilly]

Nice progress Pods! You are going to have a great camper.
Note to self. Must get truck finished so I can consider a camper!!

 

[Heifer Boy]

Looking good pods8 :coffeedrink:

In that 2nd photo I can see the thin skeleton frame you have made up. Did you just rip some ply to make these pieces and staple them together? Do you cut the foam and fit the frame around that or make the frame and fit the foam to it?

Also, when you laminated your floor, how did you spread out the epoxy to ensure an even coverage? Did you coat the foam and frame or 1/8" ply? Lastly, did you thicken the epoxy for this or just use it mixed?

 

[pods8]

Looking good pods8 :coffeedrink:

In that 2nd photo I can see the thin skeleton frame you have made up. Did you just rip some ply to make these pieces and staple them together? Do you cut the foam and fit the frame around that or make the frame and fit the foam to it?

Also, when you laminated your floor, how did you spread out the epoxy to ensure an even coverage? Did you coat the foam and frame or 1/8" ply? Lastly, did you thicken the epoxy for this or just use it mixed?

Short answer: yes.


Strips are ripped 1/2" ply. For the floor I fit the wood to the foam and clamped it all togther, seemed like it might have been easier to make the grid. For the walls I'm going the other direction by gluing/stapling the "frames" together and fitting the foam to them. I think it will be more suiting to the walls construction that way.

For the floor core I used a thickened epoxy to glue the foam and wood strips together. Then I sanded/faired it. When it was time to put down the 1/8" ply I quickly squeeged a coat of straight epoxy onto the back side of the 1/8" ply and brushed a straight coat of epoxy over the plywood grid (wanted to make sure the wood had ample epoxy on it so it didn't adsorb too much later and "starve" the joints). Then I spread thickened epoxy over the foam (under one sheet of ply at a time), I was working with a regular squeegee and a notched squeegee. I'd pour the blob of thickened epoxy down and use the regular squeegee to skim a coat over the area I was working and make sure it got pushed into all the nooks, sanding grooves, etc. to "bite" into the foam as much as I could. I then used a 1/16" V notched spreader to leave a ridged layer behind. I just worked my way down one sheet of covered, flipped on the 1/8" ply and stapled it and then moved onto the other half. (Then flipped the whole thing over and did the other side the same way).

For epoxy thickening I have bulk microspheres, cab-o-sil, and wood flour that I'll use in various combination. Mircrospheres are light and bulk out the epoxy, they aren't very structural but are stronger than the foam so they have use in the foam interfaces. Cab-o-sil smoothes things out and mainly is used because it is thixotropic (helps avoid the epoxy from running). Wood flour is heavier than microspheres but is cheap, has structural properties, and is also somewhat thixotropic.

I'm playing around with mixtures as I go. For foam interfaces a 3 parts micro : 1 part cab-o-sil is my starting point. For structural bond 2-3 parts wood flour : 1 part cab-o-sil is my starting point. For gluing down the 1/8" ply I did a hybrid so I had some wood flour in there for the grid to 1/8" ply joints but also bulked it up with micro since the majority of the joint was to foam. That mixture was 3 parts micro : 3 parts wood flour : 2 parts cab-o-sil. I mixed that to a peanut butter thickness with the epoxy.

 

[pods8]

Update 5 (43.5hrs in) Received the rear window and propane hatch and completed the rear and drive side lower wall core framing out. Still waiting on the front window so I can wrap that wall up. Have some questions in my head on the door so I'll probably sand bag that wall for now.

I glued up the driver and rear wall to get it all tied together, I'll likely have a couple quick sessions of filling in the gaps on each side still present after the initial assembly. Also will need to get in the water hatch hole (wanted to glue in the blocking to the core first). I think I might wait to drill in the water drain and waste drain ports until later on.

I'll likely turn my attention to the cab over section next for core work. Also I need to get the bulk fiberglass order placed so I can start splitting my time between core work and glassing up structures.

Driver side wall (exterior) mocked up, large hole is the propane, to the side of that is the furnace exhaust. The recessed blocking on the upper left is for the water fill (it will be under the overlapping hard wall when the top is down). The other wood blocks are for drilling in drains (and possibly the electrical connection, haven't decided on this wall or the passenger side yet so I included a block) and having something to screw them into.

Rear wall (interior), fairly basic with a 24"x24" rear window framed out and some wood hard points for attaching a mount for the bottom of the actuators to (the side wall interior had similar blocking).

The epoxied up cores clamped & weighted down (one on top of the other).

 

[Overland Hadley]

A little late, but just wanted to be sure you want to vent your heater right next to the propane vent and tank. Should be just fine, but I would have given it more space if possible.

But hey, everything is a compromise. I am not even planning on having a propane storage area, just the tank under the sink. So who am I to talk.

 

[Flagster]

Once I'm satisfied in the status of this one I'll be selling off my FWC which will offset a portion of this build cost.

I'll buy your hawk

 

[pods8]

I'll buy your hawk

You're not the first to express that thought. Just for clarification "Once I'm satisfied in the status of this one" will likely mean the shell of the new one is complete. Around that point is when I'll probably list up my hawk for sale, I'll make mention of it in my thread.

 

[pods8]

"Hot wire foam planner"

Mid weekend update: So the foam I'm using only comes in 2" thick pieces, but I wanted some 1" thick stuff so here's my DIY "Hot Wire Foam Planner".

 

[Pest]

Mid weekend update: So the foam I'm using only comes in 2" thick pieces, but I wanted some 1" thick stuff so here's my DIY "Hot Wire Foam Planner".

I like it. Gonna have to post the instructions on that little gizmo!

 

[pods8]

I like it. Gonna have to post the instructions on that little gizmo!

Same basic concept that is floating around the internet for a cheap hot wire power supply. Dimmer + transform putting power into a suitable wire. Most of the stuff I used was scraps laying around, I need to buy the transformer, fuse holder/fuses, and alligator clips.

120V input -> on/off switch (optional) -> dimmer -> fuse (optional) -> transformer: Then the transformer output goes to two wires with alligator clips to my cutting wire.

The on/off switch is optional if you just want to use the dimmer switch but with the on/off switch you can leave the dimmer set on the heat setting you want. You don't NEED a fuse but if you pull too many amps through the transformer you'll cook it, so I stuck an inline holder with a slow blow fuse in there for good measure. I happen to be using a 12V 3amp transformer from radio shack. Ideally a nickle chromoly welding wire supposedly cuts the best but I'm just using some 50lb rated stainless steel wire from homedepot that I could quickly/cheaply get and it's working fine for my needs.

The rest is just setting up a wire to do what you want. I have this wire setup between two bolts and have shims under the wire to dial in the ~1" thickness I wanted. Since I was cutting long sheets I wanted some guides to hold the foam down so that is what those two bar clamp across there for. The other clamps are just holding the cutting table down to the saw horses.