OT: Fiberglassing help, RV Repair Options

[rtalich]

Thought I'd see if there are any glassing gurus out there in the World... and hopefully get some opinions. I have not had ANY chance to work on the car due to 'other' important issues. Suck when the car gets put on the back burner!! Anyway... I am in the process of rebuilding our RV due to water damage. I’ve gotten all the rotten wood out and am currently in the process of thinking about how I am going to build the front cap. The siding was constructed using FRP (Filon) laminated to plywood. My plan is to take the Filon material and basically glass it onto a wooden frame (see pic). I will be making some curved pieces of wood blocking that will go along the top so that when the Filon material is laid onto the wooden frame it will create the sweeping curve you normally see on the tops of RV’s. I was originally thinking of attach it using epoxy resin and fiberglass from the inside and plan to totally conceal all the wood in epoxy/fiberglass to protect it and will serve as a good water barrier. My main question is… which resin would be a better choice to use? Epoxy, polyester or vinylester? My initial thought was to use epoxy because I was not sure if the other resins will shrink at all causing the Filon to distort and not sit flat on the wood frame during the curing process. I want the Filon to sit perfectly flat on the wood frame and cave in or be sucked in which would result in being able to ‘see’ the framing from the outside (does that make sense?). On the other hand, if I could use either poly or vinyl resin, I’m thinking fiberglass mat would make for an easier application and can build up quicker. I also read that poly doesn’t really bond with wood like epoxy. Any help or suggestions would be greatly appreciated.

Thanks,
Rob

[Mark Henry]

First off...I'm way far from being an expert. I'm an amature with enough experiance to be dangerous.

So are you saying you want a curve in the leading edge gap?


The usual method is to make a reverse mold, time and costly.

Option two

You could take a light bendable flex plywood, we used to call it wiggle board and then using a few ribs bend and nail it making the finished shape.

Then paint on a thin layer of epoxy, lay out some S-glass and there's a special roller to flatten the mat and work the epoxy in.
Then carefully paint on a bit more epoxy. This is tricky because the FG mat likes to slip around.
For simple curves and flat surfaces use the woven mat, compound curves the fiber mat. Try to keep compound curves to a minimum.

The only way to get a super smooth finish at this point is to bag it and put a vacuum pump on it.
On the cheap you just use plastic film, tape it with a few hoses. The tape will not stick to wet epoxy, so you have to plan and prep to do this.
You can use a old fridge compressor for the vac pump.

There's more to it, but if I can I'll help as you go.
Epoxy is weird, it flows, if you try to build up with it you come back 10 minutes later and it all flowing down like a melting wax figure.

I liked working with Epoxy better but it costs more. The medium cure give you like an hour worktime. 24 hours to cure. If you're getting the gallon bottles get the measuring pumps.
I got my stuff at http://www.uscomposites.com/
This is an example of wiggle board, it only bends one way http://www.andersonplywood.com/410/bending...forming-panels/

BTW unmixed epoxy lasts forever, so don't worry about getting too much. I've had my pumps in a few years and they still work fine.

[rtalich]

First off...I'm way far from being an expert. I'm an amature with enough experiance to be dangerous.

So are you saying you want a curve in the leading edge gap?


The usual method is to make a reverse mold, time and costly.

Option two

You could take a light bendable flex plywood, we used to call it wiggle board and then using a few ribs bend and nail it making the finished shape.

Then paint on a thin layer of epoxy, lay out some S-glass and there's a special roller to flatten the mat and work the epoxy in.
Then carefully paint on a bit more epoxy. This is tricky because the FG mat likes to slip around.
For simple curves and flat surfaces use the woven mat, compound curves the fiber mat. Try to keep compound curves to a minimum.

The only way to get a super smooth finish at this point is to bag it and put a vacuum pump on it.
On the cheap you just use plastic film, tape it with a few hoses. The tape will not stick to wet epoxy, so you have to plan and prep to do this.
You can use a old fridge compressor for the vac pump.

There's more to it, but if I can I'll help as you go.
Epoxy is weird, it flows, if you try to build up with it you come back 10 minutes later and it all flowing down like a melting wax figure.

I liked working with Epoxy better but it costs more. The medium cure give you like an hour worktime. 24 hours to cure. If you're getting the gallon bottles get the measuring pumps.
I got my stuff at http://www.uscomposites.com/
This is an example of wiggle board, it only bends one way http://www.andersonplywood.com/410/bending...forming-panels/

BTW unmixed epoxy lasts forever, so don't worry about getting too much. I've had my pumps in a few years and they still work fine.

Thanks!! I am actually leaning towards going this route and getting some bendable plywood for the curve. Then making my sure the whole surface transitions from flat to curve the way I like and then cover it with Filon using contact cement.