Moderator: eaglesdare
and it seems to me that the more elegant solution is just to chose a heavier cloth instead of adding plywood to the mix.
GPW wrote:" I am starting to realize that what I am asking about is the rigidity of the structure and not the surface resistance to damage as it seems that the rigidity will dictate the thickness of the fiberglass cloth" .
If you're worried about the rigidity of the structure , just THICKER foam ... Using more f/glas for "structure" will only make it Heavier ...
fonsan wrote:I have been following yours on youtube and it is very inspiring.
Would it be feasible with a single layer of 6oz for large flat surfaces? (or even lighter)
If you would redo your camper would you consider using less epoxy and fiberglass?
Can't wait to see your camper fully finished
fonsan wrote:GPW wrote:" I am starting to realize that what I am asking about is the rigidity of the structure and not the surface resistance to damage as it seems that the rigidity will dictate the thickness of the fiberglass cloth" .
If you're worried about the rigidity of the structure , just THICKER foam ... Using more f/glas for "structure" will only make it Heavier ...
I tend to agree, https://explorecomposites.com/articles/ ... tructures/
Doubling thickness more than doubles the "Relative stiffness" and the stiffness gain seems to be even more advantageous past 1 inch (2.54cm)
I have 4,5 and 8 cm xps foam available to me in theory combinations could be glued (4+5 yielding 9cm)
fonsan wrote:https://www.homebuiltairplanes.com/forums/threads/testing-xps-foam-for-epoxy-adhesion-bonding.34960/page-2#post-571806
"80gsm/10mm XPS backing is enough to require not-accidental force to push through a surface."
OP827 wrote:Having built my lifting roof camper with 1.5in fiberglass XPS sandwich panel roof and walls I would share some of my thoughts on the subject.
Apart from rigidity and structural strength theory of glass and foam sandwich there are other real world design cases/scenarios to consider.
What if it is raining and then the thin glass skin will amplify the rain sound into the cabin like a drum skin so the inhabitants will have to wear some ear plugs to be able to sleep? Thin fiberglass with XPS propagates the rain drop sound pretty good. Some people may like it and some may not.
What happens if some sizeable branch falls from a tree darting down towards the camper roof?
In short, I personally feel that a roof with some plywood skin and epoxied glass or multiple glass cloth layers would give more substantial sound proofing and falling subjects protection.
jakejakejake wrote:fonsan wrote:I have been following yours on youtube and it is very inspiring.
Would it be feasible with a single layer of 6oz for large flat surfaces? (or even lighter)
If you would redo your camper would you consider using less epoxy and fiberglass?
Can't wait to see your camper fully finished
Thanks Fonsan! I absolutely overdid it with the glass in regards to weight. If light weight were the only parameter I was trying to meet I would be absolutely comfortable with a single ply of 6oz glass. Especially if you're okay with doing a little repair work here and there as needed.
The exterior of my build is three plies of 6oz glass with an additional 3 plies on all the radiused joints. I tend to be rough on things and live in an area with Gnarly thunderstorms, tornadoes, and hail on average of 1/2" diameter. Dale (the wonder dog) and I will find a nice ditch to lay in in the event of a tornado, but a hailstorm or three is not out of the question in its first season of use.
With all that said I am extremely light compared to commercial truck campers. Im estimating its around 200lbs currently and should be under 3-350 with the added weight of the 12v system, water system, 270 awning, etc. Most commercial options start at 750lbs and up. Heck even the fiberglass camper shell that I harvested the windows out of is significantly heavier than the total build as it sits.
Burt Rutan is the godfather of foam-core fiberglass. Incredible mind on that guy.fonsan wrote:GPW wrote:" I am starting to realize that what I am asking about is the rigidity of the structure and not the surface resistance to damage as it seems that the rigidity will dictate the thickness of the fiberglass cloth" .
If you're worried about the rigidity of the structure , just THICKER foam ... Using more f/glas for "structure" will only make it Heavier ...
I tend to agree, https://explorecomposites.com/articles/ ... tructures/
Doubling thickness more than doubles the "Relative stiffness" and the stiffness gain seems to be even more advantageous past 1 inch (2.54cm)
I have 4,5 and 8 cm xps foam available to me in theory combinations could be glued (4+5 yielding 9cm)
Absouletly correct! I would have never guessed that my roof would be walkable, but its extremely rigid with 2" or 5cm foam. As explore composites points out the foam is basically the "web" of the beam. Its takes much more force to deform a 12" beam vs an 8" with the same web thickness.fonsan wrote:https://www.homebuiltairplanes.com/forums/threads/testing-xps-foam-for-epoxy-adhesion-bonding.34960/page-2#post-571806
"80gsm/10mm XPS backing is enough to require not-accidental force to push through a surface."
80gms is roughly 3osy I think? Freedom units is my forte...sorry. In my testing I could dent the foam with my thumb with a single layer of 4osy glass.
This brings up a good point. Make up a few test panels, maybe 20cmx20cm with varying layer counts and foam thickness, then do some destructive testing. Its great fun and will help you decide on what specs are most desirable to you.
fonsan wrote:I already bought some XPS panels for experimentation: 300kpa 8cm and 300kpa 5cm (33kg/m3) and you would not believe how rigid they are just by themselves.
fonsan wrote:My plan is to make nichrome wire a foam cutter and basically build the full trailer out of foam dry fitting everything together (and sanding corners round) only gluing the individual wall, roof and floor panels. Then disassemble and in massive sweeps turning the panels into composite with the glass and epoxy leaving a few cm without glass on all sides of the wall panels. Glue all the box together and then bridge the glass between them over the rounded corners prepared earlier. I want to lay down as much epoxy as possible when the panels can lay on a flat surface avoiding having to battle epoxy that flowing of the surface.
fonsan wrote:Not going for pure box look but the front will be wedgeshaped and the rear needs to be stiffer as a major portion of the rear wall will be a garage door that opens up for loading and unloading the motorcycles.
twisted lines wrote:And I spent days attempting the shape I am looking for; with a new program windows 7 won"t do
With Hours trying the next Radi And multiple times.
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