fibreglass experts Options

[scotty b]

I have to make a custom bumper for a car. I am familiar with the mold process but what I do not know is what type of expandable foam I should buy. I am planning to make a wooden box ( form) to pour the foam in, then attatch it to the car and start cutting and sanding to get the desired shape. What I need is something that will expand and still be closed cell enough to handle cutting, sanding and shaping, then can handle bondo being applied to get that oh so smooth ready to be painted, finished buck. (IMG:style_emoticons/default/wacko.gif)

[Dr Evil]

Plastic wrap can work as well, no?

[stepuptotheMike]

Plastic wrap can work as well, no?

that's for wrapping around the middle to help you lose pounds. (IMG:style_emoticons/default/biggrin.gif)

anti wrinkle cream there might be.... but anti fat bastard cream there ain't (IMG:style_emoticons/default/piratenanner.gif)

[scotty b]

Plastic wrap can work as well, no?

No, the final buck needs to be perfectly smooth and actually painted as if it were the finished bumper. That then gets coated with mold release, gel coat and then the glassing begins. THAT makes the female MOLD that the real parts are made from. That is why the initial buck needs to be bondo'd and worked to perfection, any imperfection will come out in the gel coat on the female mold.

[scotty b]

Plastic wrap can work as well, no?

that's for wrapping around the middle to help you lose pounds. (IMG:style_emoticons/default/biggrin.gif)

anti wrinkle cream there might be.... but anti fat bastard cream there ain't (IMG:style_emoticons/default/piratenanner.gif)

SWEEEET a battle of the bigguns. Someone call Donald he needs in on this (IMG:style_emoticons/default/stirthepot.gif) (IMG:style_emoticons/default/chair.gif)

[URY914]

(IMG:style_emoticons/default/sunglasses.gif)--><div class='quotetop'>QUOTE(scotty b @ Jan 5 2011, 08:08 PM) </div><div class='quotemain'><!--quotec-->
The sheets and particularly spray foam just isn;t going to cut it. I'm talking about a whole front bumper. That stuff may be great for a small project or a home doer, butI have to keep this within a reasonable budget. Surfboard blanks crossed my mind but the amount I would need would be $$$$ plus shipping got to be even more $$$$$$. [/quote]

You're not going to find anything cheaper than foam sheet and the spray can foams. Here is a shot of a ricer that had his front bumper using the only stuff from Home Depot, so it can be done on the cheap. Fill in the voids with the spray foam and make your female mold. It will take some work to get the mold perfect.

[buhs914]

[quote name='URY914' date='Jan 6 2011, 05:01 AM' post='1414236']
(IMG:style_emoticons/default/sunglasses.gif)--><div class='quotetop'>QUOTE(scotty b @ Jan 5 2011, 08:08 PM) </div><div class='quotemain'><!--quotec-->
The sheets and particularly spray foam just isn;t going to cut it. I'm talking about a whole front bumper. That stuff may be great for a small project or a home doer, butI have to keep this within a reasonable budget. Surfboard blanks crossed my mind but the amount I would need would be $$$$ plus shipping got to be even more $$$$$$. [/quote]

You're not going to find anything cheaper than foam sheet and the spray can foams. Here is a shot of a ricer that had his front bumper using the only stuff from Home Depot, so it can be done on the cheap. Fill in the voids with the spray foam and make your female mold. It will take some work to get the mold perfect.


[/quote]

I like that fancy holding device. As for the foam I would have to agree with using the pink stuff and just layering it to get the size you need. I've noticed that the florist foam stuff costs a little more per volume than the pink stuff..

[Borderline]

The polyester resin will eat up a lot of stuff and most foams. Surfboard blanks are made of polyurethane foam than can stand up to the polyester resin. I made a mold of my targa top and the polyester resin ate thru all the wax mold release compound and wrinkled up the paint. Try using an epoxy resin for the first layer of your mold. The epoxy will not melt thru the various materials. After it cures, you can add a bunch of stiffening layers to the mold using the cheaper polyester resin. FWIW

[r_towle]

Florist foam, the green stuff, holds up to "some" resins, but not all.
Some of the epoxy resins will eat up that type of foam also.

Still, the cheapest way to go is pink foam for major build, spray foam for the cracks...smooth it all out and use plaster to cover the whole thing and smooth it out perfect.

try this place.
www.foamation.com

rich

[scotty b]

O.K. I'm going to try the pink foam since it is both cheap and local. I'll post pics when I get to that point. I won't be starting this for a couple weeks. Thanks much for the info (IMG:style_emoticons/default/beerchug.gif)

[RJMII]

I'll post pics when I get to that point.

Woo hoo!! Pics ROCK!!! (IMG:style_emoticons/default/aktion035.gif)

at last we'll see what this secret non-914 project is. (IMG:style_emoticons/default/biggrin.gif)

Then I can copy you and make a ricer front end for my car that is still 914-esque in style.

[Bartlett 914]

Still, the cheapest way to go is pink foam for major build, spray foam for the cracks...smooth it all out and use plaster to cover the whole thing and smooth it out perfect.


rich

Drywall mud? Or is the same thing as plaster?

[76-914]

Stay away from from the polyester resins; unless you like shrinkage and warpage. And I can only imagine how that long span will twist on you. Try this: http://www.aircraftspruce.com/menus/cs/epoxy_aeropoxy.html
http://www.aircraftspruce.com/catalog/cmpages/rutan.php
or my favorite
http://www.aircraftspruce.com/search/searc...ss&search=1

Is weight a factor? If so, you'll need to fab up a vacumn bag set up, also.

[andys]

Try looking at some of the projects on here.....

http://www.fiberglassforums.com/

I'm a member to this forum and they have some good folks that can help you out.

Scotty b,

Definately worth your while to go to the fiberglass forums as URY914 suggests. Follow his link; I believe there's a auto body exterior section (or something like that). Everything in this thread and more is discussed there, plus you're likely to get many other valuable tips, tricks, and ideas. You'd be remiss not to go there.

Andys

[geniusanthony]

The cafe racer board I frequent also swears by florist foam and when necessary cover in foil for that first layer to preserve the mold. Back in my model airplane days, I would use monokote(sp) to save the mold and function as a mold release too once waxed. Think of that as iron on adhesive backed mylar shrink film.but that's my experience.

[GS Guy]

I believe Blueovalz did his car using the florist foam - might try contacting him for any tips? He obviously knows his way around doing foam and fiberglass body mods:
http://www.cardomain.com/ride/2168777/1971-datsun-240z

He currently posts on the Yahoo/Manta groups site - switched his focus to doing a full tilt LSx powered Mirage.

Jeff