Any good how 2s on making large fiberglass panels without molds

[Jonny Hotnuts]

I am rebuilding my entire front end.

I have hand laid fiberglass on shaped foam but is there a better way to do it without having a mold and using blown fiberglass. I want the entire front bodywork to be able to be removed in one piece without having the increased thickness of the foam it was built on.


Thanks

-JH

[hotrod]

Are you doing a fire wall forward one piece setup?

Do you have the shape well defined so you can build a series of patterns connected with stringers to create a wire frame male form?

On small pieces you can sometimes get away with using hot melt glue and some thin wood stringers to build a skeleton then cover that with stretch film. (sort of like a fabric covered model air plane structure) The nice thing about using hot melt glue is it is strong-tough and sets quickly. If you screw up you can cut it or pull it apart and do over with out too much brain damage.

I have also built a male form using paper mache with newspaper and white glue (takes a long time to build but no fumes), or aluminum screen on a wood strip form covered with saran wrap film. The nice thing about the aluminum screen wire is you can form it to some extent above the shape of the stringers.
You still need to build up some parts of the male shell to get the form right, I think they all end up creating a huge mess.

I would like to know if anyone has any more elegant methods.

Larry

[Unkl Ian]

Laminate and carve Styrofoam blocks to shape.
Seal with PVA glue,otherwise the resin attacks the foam..
Vacuum bag Fiberglas cloth over form.

Dissolve Styrofoam with Acetone when finished.

[JackD]

The cheap deal , home method. is to build the shape you want with the foam and materials you already know how to work.
At the point where it meets the body make it just enough smaller so as to allow the thickness of you final part.
Skin it with cloth.
Not the expensive fiberglass stuff but a stolen bed sheet.
Use sanding resin that has a lot of wax in it so you can sand it easily.
Put a top coat of hard resin on it to gloss it.
Shoot on some mold release and lay up your part.
Remember you have to consider getting the male mold out after the new part has cured.
Depending on the shape and size of the part, you can use air or water or both.

Kent, howdidido ?

[UltraCarbonFiber]

Make sure you test the foam you are using and choose a resin that will work.  If you're using epoxy that will work with most any foam but styrenated resin will melt several types of foam, example styrofoam.  2 part Urethane foam will hold up to ester based resins well.  Another thing to add to the last post is if you use a polyester skin coat of resin with wax in it you have to let it cure and sand it or if adding another layer of resin add it withing 30 mins or it will not stick to the previous layer.  If you add another layer of resin soon enough the wax in the layer beneath will keep rising to the new layer to seal off the resin from the air so it can cure to the point where it sands without gumming up the paper.  Also you can buy the wax additive separately and add it to the resin layer that needs it.  The cool thin about ester resins is they don't fully cure unless the resin is cut off from the air so you can leave a job for the night and come back and start laminating again right away.  With most epoxies you wil be sanding every time a layer cures if you need to start laminating again. 

I really would suggest building a mold if you can since doing it this way is so much work anyway. It would suck to have to do this twice if you ever bang up the original.  Oh well, you could always change your mind and build a mold any time.. up until the time it gets hurt anyway.  One other thing that might speed things up for you is to just sand your foam well with the correct shape and spray it with Duratec high build composite tool primer.  With a few coats you can fill in the foam and wetsand the entire thing, release it and start laying up your front end. PVA should work fine as a release for this type of thing but go with a semi perm release and sealer if you ever build a mold off anything. Chemlease makes a nice product.  Sorry for being so long winded on my first post,           

[JackD]

Very good information from Adam and a valuable contribution that inspires one to learn and do it himself.
When you understand the whole of the sport, you find that is the most satisfying part of the huge amount of time that leads to the best return on investment.
What I said was the simple bait version, designed to draw Kent out of his shell with more detail.
Adam stepped up and that is even better.

[John Burk]

Jack Costella covers his foam with dry wall mud which he sands and waxes .

[1212FBGS]

drywall mud...oooooooh....lol.... holds way to much moisture, but then again it definitely wouldn’t stick.... it would twist and distort and keep the resin from obtaining the proper barcole but it wouldn’t stick..!.. Oh yeh if ya use mud don’t use PVA you need to use PV6.   Home depo sells urethane foam that wont disappear with polyester resins. They sell it in 1",1.5", and 2"thick. Peal off the silver paper and you can glue it together with bondo....I hate shaping foam... the dust always wind up getting it in the crack of my ass
Kent

[JackD]

Hey Kent
With some of my "Dunlap" modified suspenders, the dust will be less of a problem for you but your part time job as a plumber would suffer.

[JimW]

I just finished a layup over (everything I could find - plexiglass, styrofoam, foam in a can, florist foam (easy to shape) and drywall mud (yes - it took a long time to dry) masking tape), wrapped it all in saran and went at it with cloth and resin.

This was my first time.  It was fairly easy.  It looks like hell. 

It will take a lot of filling to make look half decent - which is where I will stop.  This is my 'tester' project.

If I had it to do over I might do it like http://www.recumbents.com/wisil/wianecki/frank-n-liner/default.htm  (but I've never done it this way either, and by the time I get done I may have different ideas).  I will use the build up design as a plug for a female mold, and then layup the 'real' body in this mold. 

Second option is to use Kent's friend that has a big 3 axis mill to cut a female mold out of a big block of foam.  Skin it, release coat it, and then use that as the mold to lay up the body.  Probably pretty accurate, but somewhat expensive for the mill work.

I second the 'this is a lot of work' statement.  As a matter of fact - this is a whole hell of a lot of work.  And more.  Take whatever time you have allowed for this and multiply by 10.  I thought I'd knock this out in a week and a half.  MONTHS later it's still not done.  (Now, I'm learning as I go, but there have not been any show stoppers, it just takes time.)

I think the biggest problem is getting 2 sides the same shape (or two anythings the same shape for that matter).

Thanks,
Jim.

Oh yeah.  make sure that saran is stretched really smooth.  Every wrinkle shows up.  And, epoxy will stick to dry drywall mud, and you will never get all the drywall mud off.

[Unkl Ian]

And, epoxy will stick to dry drywall mud, and you will never get all the drywall mud off.

That's why it needs to be sealed.

[JackD]

There was a World Famous Bonneville racer that built up a liner over Clark Foam with carefully shaped plywood stations all along the length of the body.
He had a well known surfboard shaper with what was supposed to be a good eye do the filing.
Only the best materials were used and the long effort seemed worth all the work.
Before paint, a longtime (from the beginning) Bonnneville regular and with at that point 42 years working in a boatyard  took a look at the finished body project.
The first thing he said to the owner, builder, operator, that he new from a baby, was that it was curved over it's 25 foot or so length like a banana.
It was finished to run, only ran a short ways on private time and, the project was abandoned.
Later, Kent, just another kid, did a major modification to another liner for the famous racer, and the rest is history.

[UltraCarbonFiber]

Here is a pretty decent starter book with a chapter on plug building :

http://www.amazon.com/Fiberglass-Other-Composite-MaterialsHP1498-AutomotiveRacing/dp/1557884986/ref=sr_1_9/104-2910036-5170358?ie=UTF8&s=books&qid=1191278135&sr=1-9

[sockjohn]

I am rebuilding my entire front end.

I have hand laid fiberglass on shaped foam but is there a better way to do it without having a mold and using blown fiberglass. I want the entire front bodywork to be able to be removed in one piece without having the increased thickness of the foam it was built on.

Thanks

-JH

I assume by "blown fiberglass" you mean chop gun?  You can hand lay anything you can use a chopper gun on with better results.  The only real trade off is time.

You can get Divinycell high density foam in 1/8" and 1/4" thick sheets and could make a sandwich construction with that (encase both sides in glass)   This would be stronger and more ridged than the equivalent layers of glass by itself.  I would do this regardless of if you build a mold or mold less.  Lightweight fiberglass hoods are often very floppy, especially if they have large flat sections - this actually increases air drag. 

When you heat soak Divinycell it will conform to a mold well, and once cooled will "set" to that shape.  You can't just heat it with a heat gun, you really need to heat soak it in an oven, makeshift or otherwise.

If you do a one off mold less construction, you may very well end up with an eight inch of filler anyway!

The problem with mold less construction is the filler goes on the finished project, not the mold.  This has a big effect on long term durability of your paint job.

I'm not sure why you don't want to build a mold, but it isn't all that bad.  The most time on this is going to be getting the proper shape and finishing, and either way it's slow going and lots of long board time.

[hotrod]

Any one used the paper hexcel cores or products like coremat or corematxl?

http://www.hexcel.com/NR/rdonlyres/599A3453-316D-46D6-9AEE-C337D8B547CA/0/HexwebAttributesandProperties.pdf

http://www.lantor.nl/composites/fr_comp/frame_comp.html?../coremat.html

They also look promising for hand layup of complex shapes.

Larry