Fiberglass Do it yourself

[Forrest747]

Ok thinking about the sides still and the idea of doing it in Fiberglass intrest me. So what advice would you give? What paint would I use. Thank you

[kennyrayandersen]

I'm going to use a ply fiberglass epoxy on the outside, 1 inch thick blue/pink pol;y styrene foam core and one ply fiberglass epoxy on the inside for the walls and roof and all of the shelving. On the platform (base) I will use 2 inch thick foam and two plies inside and outside. I'm thinking right now to use a vacuum pump and do it at room temperature. I will mount the frame to the floor and I will put some plywood inserts into the foam for locally reinforcing the attachment. I'll also frame the platform with 1x2s.

Several people have recommended the Raka system for being reasonable priced and good quality, so I'll probably use them (although a buddy of mine has a big roll I might dip into for the fabric.

[SlyTerry]

If your going to use styrofoam with a glass/epoxy skin you had better perforate the foam surface with as many pin holes as you can get and vacuum bag the whole shooting match. If this first step is not taken then the slightest impact or tear will lead to foam surface failure and hence the bond between the two material will be broken. What happens during impact is that both materials deform inwards and cells within the foam collapse permantly damaged and don't return to the previous level. The glass/epoxy skin however does return nicely. With climate temperature changes over the course of the year will lead to sever panel delamination due to the materials now having different rates of thermal expansion/contraction. If you use a PP honeycomb core this problem goes away at a minimal gain in weight. 0.5 lbs per cubic foot is the HC density.

[madjack]

...if you build with wood, you can coat it with 3+ coats of epoxy resin(FG cloth optional) and paint with a marine urethane paint such as Interlux Brightsides or if you want the woody look paint the epoxy with either an auto clear or a spar urethane.........
madjack

[starleen2]

I'm going to use a ply fiberglass epoxy on the outside, 1 inch thick blue/pink pol;y styrene foam core and one ply fiberglass epoxy on the inside for the walls and roof and all of the shelving. ....

You might want to check on the Blue stuff - I used some this past week for the insulation value and found that it has a thin plastic sheeting on both sides - The sheeting is fairly easy to pull off and will have to be removed if you want to prevent delamination. It is hardly noticeable sine it is easily cut with a utility knife.

[Forrest747]

What I am thinking is doing the build with 4X10 plywood and then coating with fiberglass so I can paint. In doing research for the aluminum, the painting just seems so much work. Yet at the same time I plan on painting the roof black to match the color scheme of my Jeep. Although I am not sure about painting it black, since it will be much hotter. I am not sure any more I guess I have a little bit to figure this out.

[kennyrayandersen]

If your going to use styrofoam with a glass/epoxy skin you had better perforate the foam surface with as many pin holes as you can get and vacuum bag the whole shooting match. If this first step is not taken then the slightest impact or tear will lead to foam surface failure and hence the bond between the two material will be broken. What happens during impact is that both materials deform inwards and cells within the foam collapse permantly damaged and don't return to the previous level. The glass/epoxy skin however does return nicely. With climate temperature changes over the course of the year will lead to sever panel delamination due to the materials now having different rates of thermal expansion/contraction. If you use a PP honeycomb core this problem goes away at a minimal gain in weight. 0.5 lbs per cubic foot is the HC density.

I was going to use either the blue or pink extruded stuff (actually I was thinking about getting some made and then custom sliced -- there is a place near Fort Worth that does it, so I was hoping to get it 5 foot wide). Structurally it's the same as the home depot foam which is around 2 Lb/ft cubed. I was planning on roughing it up with 80 grit sand paper. I can vacuum bag the sides easy enough, but it would be tough to vacuum bag the curved outer portion unless I build some tooling which I didn’t want to do. I was going to join the foam like barrel staves in the curved part, glass the inside, install it in the tear and then hot-wire the curve on the outside and then use a wet layup on the outside. Then, I’ll joint the outside with tape at the corners and fillet and tape the inside. I’ll probably put an extra ply on the outside up about halfway up in the front to help reduce any impact damage, which I agree it probably the critical condition for the sandwich.

If I can’t get the expanded polystyrene in bulk and cut like I want (you can get up to 5’x5’x10’, or so they say), I’ll use the Home Depot foam and I will be careful to remove any non-stick surface and or rough up the exterior so that the glass-epoxy will stick. I will do some tests of the bonding (4-point bending, and core shear) and basic sandwich for I do the whole thing to make sure the ‘system works. I will also include some impact testing (though I’m not sure what I will do with the results – mostly a feel-good test I think).

I figure that the honeycomb core would be more difficult to work with because I would HAVE to bag the curved part, I’d also have to either use an adhesive layer or get a self-adhesive prepreg, but I ain’t got an autoclave, so that won’t work (maybe there si another technique to which I am not familiar?). Also, at .5 Ld/ft cubed the shear allowable has to be much less than the Home Depot foam (not that it might not work, it just seems less robust). What are you using for a shear allowable for the poly honeycomb? The only structural core I’m familiar with is either aluminum or NOMEX (there are some other more exotic and obscure ones, but those two are the most common).

See any problems with that approach? Each panel will be frames out with either a 1x1 or a 1x2 so that they can be screwed and biscuited together.

If you have more information about the poly core I’d love to hear about it as well as any techniques for using it. It sounds interesting; I’m just not familiar with it. I get jaded a bit I suppose because we use some pretty expensive stuff at work which IMO would be difficult to reproduce at home in the garage. If I were going into production you could invest in some decent tooling, but I frankly make a bit too much as a consultant to consider making tears for a living – not that it doesn’t sound more fun than what I’m doing… it just baby needs new shoes…

[Esteban]

I'm building a teardrop with a fiberglass outer skin that will be painted with marine paint. The walls are sandwich construction with 1/4" plywood on the outside. It seems more than rigid enough. The outside teardrop walls are 11' long by 4" 5" high. Inside the cabin the walls are just under 4' tall. Because the side is larger than 4' x 8' the outside plywood skin is pieced together, with 3 butted pieces. The front nose piece is a full 53" high by nearly 4' wide. The second sheet is run long horizontally, butted up to the first one (the nose) inside the door opening. That way there's less of a butt joint to back up with framing. A third 5" high horizontal piece is butted above the second sheet to fill in up to the roof line. All joints are backed up by the sandwich framing. I glued and stapled the plywood to the sandwich frame. It became a very rigid unit. Once the wall was fiberglassed the joints were filled in and I have one smooth wall unit (after some sanding and fairing). Then the wall frame was insulated and the inside cabin skin was glued (epoxied) in place. I see no need to pay extra $$ for plywood lager than a normal 4' x 8' sheet if you're going to paint the fiberglass.

[kennyrayandersen]

I'm building a teardrop with a fiberglass outer skin that will be painted with marine paint. The walls are sandwich construction with 1/4" plywood on the outside. It seems more than rigid enough. The outside teardrop walls are 11' long by 4" 5" high. Inside the cabin the walls are just under 4' tall. Because the side is larger than 4' x 8' the outside plywood skin is pieced together, with 3 butted pieces. The front nose piece is a full 53" high by nearly 4' wide. The second sheet is run long horizontally, butted up to the first one (the nose) inside the door opening. That way there's less of a butt joint to back up with framing. A third 5" high horizontal piece is butted above the second sheet to fill in up to the roof line. All joints are backed up by the sandwich framing. I glued and stapled the plywood to the sandwich frame. It became a very rigid unit. Once the wall was fiberglassed the joints were filled in and I have one smooth wall unit (after some sanding and fairing). Then the wall frame was insulated and the inside cabin skin was glued (epoxied) in place. I see no need to pay extra $$ for plywood lager than a normal 4' x 8' sheet if you're going to paint the fiberglass.

That will work fine. If a person can get the over-sized plywood though, they may be able to save a bit of time, which is money. As you noted the great thing about fiberglass is that you can get it 60 inches wide which will cover the whole shebang and cover any seems. With the big sheet goods there is no need to sand and smooth before glassing, but either way will certainly work.