Insulated vs. solid walls

[kennyrayandersen]

you really only need some framing maybe around the door and where the hatch and the frame attach. Other loations could use local plywood inserts inplace of the core. this would aloww you to use inserts that wil accept a thraded screw, or a wood screw (I prefer the inserts). Adhesive can be every bit as strong as fasteners. When the plywood is glued to the core on both the inside and outside, it becomes incredibly strong. Hopefully after I finish thinking about mine, I'll post some pictures of the construction techniques which should result in a very light-weight structure that is also very robust.

the quarter inch plywood is likely overkill. @ X 1/8 would be very strong (build some test strips to prove it to yourself. You could go a little thinker on the botlom just for robustness against bouncing rocks etc.

You can use epoxy (aircraft) resin with polystyrene (Home Depot rigid insulation)

or

Polyester resin (boats) with Urethane (aircraft) foam

Since the urethane foam is considerable more expensive than the polystyrene, it is like likely cheaper to use the epoxy/polystyrene even though the epoxy is more expensive than the polyester resin.

When using wood, my guess is that the epoxy will glue it to the polystyrene just fine. You do have to rough up the surface of the foam before gluing it to the wood.

Sometimes when taking apart old airplanes you have to virtually beat the parts off of it and that is just for faying surface sealant. Real adhesives, when applied properly (nothing like following directions) are not only incredibly strong, but will last the life-time of the whatever-it's-gluing.

[Muggnz]

the pages on Laminated SIPs?

@

http://tnttt.com/viewto ... c&start=60

May help.

There's certainly more to this subject than meets the first eye to see it.

[kennyrayandersen]

that's it exactly it. I'm still reading through all the links -- good stuff though. I'll probably end up getting a vacuum pump, but to do a veneer on a headboard, not to do a trailer.

The other way of doing this is to just use fiberglass and a wet layup. It's not quite as light, but I just want light-weight, not to fly.

The SIP method will work especially good for the flat panels, but is more difficult for doing the curved center section. You need some tooling to suck the core and facesheets of plywood together. Not imposible, but definately some extra work. A combination of sip for the sides and wet layup for the center would avoid having to make a lot of tooling. Hmmm...

[SaGR]

For those who built sandwiched walls -

Our frame has the angle iron going up:



What is the best way to cover that upward angle iron?

I was initially thinking of going flush to the inside of the trailer, but that would give us nearly and inch outside of the angle iron (still would have plenty of clearance for the wheel).

So I'm guessing we'll be building from the outside wall flush to the angle iron and building inward.

Just trying to flesh this out. We're leaving in a few minutes to get the floor material (YEAH!).

[toypusher]

You could try something like this:



Of course all of the material thicknesses could be changed. I think that I would use 1/4" for the outside skin, if I were building it now. I probably would not use the bolts either, just use screws. This is an old drawing, but gets the idea across, I think.

[Miriam C.]

You can put a row of 2x2's along the edge and put the floor on top or build the sandwich and drop it in Either way will work. Just really waterproof that edge that sits in the angle. Remember the angle will rub some over the years and to tie the sides well. On top or the side will work.

[toypusher]

You can put a row of 2x2's along the edge and put the floor on top or build the sandwich and drop it in Either way will work. Just really waterproof that edge that sits in the angle. Remember the angle will rub some over the years and to tie the sides well. On top or the side will work.

You could also cut some angle iron of the same demensions and put it the other way to fill the gap (creating a box). Just short pieces of 3" in length spaced a couple of feet apart would do and not add that much weight. Then just build on top of it and let the outside skin run down over the outside of the frame.

[SaGR]

Cool ideas! Thanks folks!

We'll build it standard per the build docs and then build up the difference as needed. We'll be sitting around 1 1/4" thick on the floor and the angle iron is 1 3/4".

I may just sandwich the floor to gain the extra thickness.

[SaGR]

OK, so we finished the frame for the floor (pics later).

I think we'll go with a combo of all the ideas. It'll take me a few to figue out exactly how we're going to do it, but once I get the floor attached to the wooden frame I'll be able to see what will work better.

[SaGR]

Floor is done, still need to insulate and put on the roofing cement.

I need to build up 1/4", so I might go ahead and just sandwich the floor. If I go this route I'd only need to tar the bottom ply correct?

I had to laugh - I was so careful to make sure the floor was square. Wouldn't you know it, the trailer isn't! As a good friend would say "Ain't 'dat a b!7ch!"

www gallery updated. More tomorrow!


Moved this post to a new build thread. http://www.mikenchell.com/forums/viewtopic.php?p=224326#224326