Making Moulds

[Daz K]

hello everyone

i need a little advice from people "in the know"

i know this a Boat design forum .. but the reason im here is not to build a boat

im going to attempt to design my own bodykit for my car . using fibreglass . i want to design my own kit .. so i need to do this myself

please forgive me for using a boat forum for my questions

right .. ANY help would be GREATLEY appreciated

i am familair with using small amounts of fibreglass , so i know the basics

what is a mould built from?

what materials are needed?

where can i get these materials?

what tools will i need?

any books i can buy about building moulds?

how difficult is building a mould? am i wasting my time here? lol

any websites/links that may be of use would be great

thanks people

Daz K

[CDBarry]

Female molds are usually made from plugs which represent the actual hull surface.

Plugs can be made from wood (often strip planked), plaster over chicken wire, or various types of foam over wood or whatever frameworks.

A material called C-Flex can be used to make a fiberglass surface without use of a mold. This can be used as the hull itself or as a plug. Bill Seeman in New Orleans is the inventor of C-Flex, and Dave SIntes is a major user and expert on it.

[Daz K]

dont mean to be a pain .. but what exactly is a plug? i dont know all these words lol

any useful sites u can direct me to?

cheers

[Jeff]

A plug is a male shape over which a female mold is layed up to then prodduce 'male' hulls out of that mold.

One web site: http://www.valsparcomposites.com/mol...troduction.htm

Marine Composites by Eric Greene Associates
http://boatdesign.net/cgi-bin/bdn/jump.pl?ID=216
(has detailed info but also an overview of the female mold, one-off, and vacuum techniques)

A video - "A Step-by-Step Guide to Molding Fiberglass":
http://boatdesign.net/cgi-bin/bdn/jump.pl?ID=2757
Other books:
http://boatdesign.net/Directory/Tech...ng/Composites/

[Daz K]

awesome mate thats a great help thanks!

anymore suggestions/help wont go a miss

thanks

[Jeff]

What size is the biggest part you'll be creating?

what is a mould built from?

what materials are needed?

where can i get these materials?

Typically you'll create a perfectly smooth and fair plug as CDBarry describes; once it's as perfect as possible you use several coats of was and PVA mold release. Then you apply gel coat and build the mold of fiberglass (the size and number of parts you want to layup in the mold and pull from it depends on the degree of "overbuilding" and reinforcement of the mold, but it has to be solid so it doesn't distort.)

Now for very small parts if you're only producing one or two, you might even get away with using a pourable semi-hard rubber like http://www.smooth-on.com/ - your mileage may vary (I tried it on much too large a part and ended up getting distortion in the final product, but I think for a very small part that you would only produce one or two of, it could be a quick (though somewhat expensive) shortcut.)

[Daz K]

u have been a great help mate

i can thank u enuf!

cheers

Daz K

[Jason Cosler]

Jeff,

I'm interested in your experience with the semi-rigid rubber (plastic?) mold. Specifically, type and size of the part, product name, type of distortion (shrink, twist, etc.), durability. I'm guessing distortion may be the main drawback (?).

I'm looking at some alternate mold making schemes for small hulls (< 20' LOA)with an emphasis on reduced labor costs. So one option is casting female molds as opposed to standard lay-up. More costly in materials (?), but a potential savings in labor. For a small hull, the process might utilize a steel cargo container cut in half with plates (i.e. pieces of the cut-up container) placed inside and welded to reduce the volume of the mold, thereby reducing the shrinkage/distortion of the casting material (I assume shrinkage is affected by be overall mass of the cast). I'm thinking the interior would also have welded struts or ribs (think small I-beams) welded onto the plates to help hold the casting material in place. From there it's simple, right? Suspend the plug in the mold and cast around it. The Task line from Smooth-On makes some decent claims with respect to impact resistance, shrinkage, etc., but what kinds of volumes it can be mixed and poured in is a question.

Impossible?

[Eisa Hasan]

Hi Daz

u can check http://www.Fibreglast.com/

it might be helpful

[spartin]

i made the molds for factory five racing it was a 5 piece mold and could be vaced to this day 200 parts no problums car was shelby cobra

[spartin]

Originally Posted by spartin

i made the molds for factory five racing it was a 5 piece mold and could be vaced to this day 200 parts no problums car was shelby cobra

heres the car

[Jason Cosler]

I sort of know what I'm looking at here. Trying to orient myself by that classic Cobra "grill." Does the mold separate in lateral chunks (i.e. as if it were cut across the car) or does it come apart around the contours of the panels? Lots of questions. What liquid plastic did you use? Did you pour the whole mold first and cut it or pour it in sections? One of the issues I'm trying to sort though is how to keep tight tolerances on a multi-piece mold.

[spartin]

heres my e mail leave your phone and i will call to explane in detail to you monomaina@attbi.com

[spartin]

heres a pic of the nose

[spartin]

lets try this agan