How to make plug/mold for fiberglass parts. . .

atomicjoe23

Well-Known Member
If anyone could give me some advice on how to make molds/plugs of pre-existing parts I would really appreciate it. . .I'm not trying to copy anyones stuff and put them out of business, it's just that I know what I want and no one makes it. . .I can use some pre-existing stuff and modify it to my needs/desires, but I'm not sure how to make the mold/plug so that I can recreate it. . .

. . .I'm gonna start out small and just do a tailsection for my sportbike. . .I've got an '02 Yamaha YZF-R1 that I wanna put a TZ250 tailsection on. . .I'm gonna make a new subframe to fit the tailsection on the bike, but the TZ250 doesn't have a tail light cutout and I was planning on using the tail light from an Aprilia RS125 because the lines should flow together very well. . .so I need to modify the tailsection to accept the tail light. . .I want to do the mods to the tailsection and then make either a plug or a mold (I'm not sure which one would be best for this application. . .so if you have a suggestion I'm all ears) of the modified piece because the only piece I can get is from a place that doesn't have the best fiberglass in the world. . .

. . .once the plug/mold is made should I use sheets of fiberglass or chopped mat to make the new piece. . .

. . .I've got plenty of time to dork around with this and fiberglass is something that I've wanted to learn for a while. . .so I would love to get some advice/tips from those of you with experience. . .

Thanks!
 

atomicjoe23

Well-Known Member
In the below thread (page 4) the buggy is going into to get fiberglass work done and it has plywood attached to the chassis. . .this is the second buggy I have seen with plywood on it when going to get custom glasswork done. . .

http://www.race-dezert.com/forum/showthread.php?t=62894

Is the plywood there to attach the foam too???

What kind of foam is that??? Is that the kind that comes in big blocks or is it a spray on foam that I have seen mentioned in another thread???

Also if you look at page 5 of the thread in the close up pic of the side of the buggy you can see a bunch of numbers on the foam. . .what are they for???

Thanks!!!
 

MARXICO

Well-Known Member
Real simple

1) pack the area you want to shape with styro foam , oversized , you can cut and glue foam to sculpt to desired shape

2) carve and sand to desired shape with in roughly 1/4 inch

3) cover foam shape with white glue and let dry

4) cover part with bondo shape and sand to detail desired

5 you can make a mold from this part or

6) apply fiberglass mat to part cut in small pices and overlap , 2 seperate layers of glass

Sand / bondo , when ready for paint first pour Acetone on foam .. it will all dissapear now you have your finished part ... dont be afraid to grind and sand down to make lighter and repair inside sirface where foam was with some bondo ... paint and install
I use to make motorcycle gas tanks this way

Keep in mind matt is forgiving but not as strong as cloth run cloth as runners or support for schere strenghth

pre cut the pices and lay out befor mixing resin

Squeegy out as much resin as possible makes a lighter and less brittle part

Cloth is stronger than matt ... harder on corners ... use smaller cut ip pices of mat for thoes spots

PeP Bouys should have every thing

Clean with Acetone

LooK for fiber reinforced resin or hair / stringy bondo with supirior strenght

Mix small batches .. when it starts to catilize or go off stop work do not try to use material

buy a box of 100 ruber gloves .. change them every time you get resin on your hands .. the easyest way to work

it is no mor than paper mache ... arts and crafts

Insert brackets or supports made from metal or masonite in between the lamenated layers

work in a well ventelated area you are woorking with stuff thak can explode or asfixiate you
Mask when grinding and safty glass at all times one splash and its over
A over catilized batch will catch fire so be aware of your inviroment... dont make your family breath your hobby it is a crappy buzzand is deadly even in powder form (dust from sanding )
to stop the itch wash with vinigar where disposable clothes
do not eat drink or smoke ariound this stuff

After all that ... have fun you will suprize your self on how easy it is
 

baja619

Well-Known Member
In the below thread (page 4) the buggy is going into to get fiberglass work done and it has plywood attached to the chassis. . .this is the second buggy I have seen with plywood on it when going to get custom glasswork done. . .

http://www.race-dezert.com/forum/showthread.php?t=62894

Is the plywood there to attach the foam too???

What kind of foam is that??? Is that the kind that comes in big blocks or is it a spray on foam that I have seen mentioned in another thread???

Also if you look at page 5 of the thread in the close up pic of the side of the buggy you can see a bunch of numbers on the foam. . .what are they for???

Thanks!!!
The plywood panels are there so that the plugs can easily be removed and taken to create the molds for each piece. This makes it modular and each piece will retain its structural integrity w/o compromising the final shape and finished contours of the body.

The Foam is a two part A/B mixture that expands after the chemical reaction takes place. Once dried (very quick) we then can assume shaping as desired. There are different types of foam with different qualities. You get what you pay for. We have never used the Foam Blocks but would consider it for sure as it seems likely to be much less mess. But then again once you start shaving and shaping well the Foam gets every where. It is worse then metal grind grit and dust and will track on your shoes anywhere you go.

The numbers are used to reference asymmetry and alignment of the bodies shape from side to side. This is mainly used as a rough starting point, and you should make a template that can be reversed and used on either side.

FiberwerX
Micah
 

MARXICO

Well-Known Member
The 2 part urthane foam is also avilable at home depot in spray cans two kinds low expanding and expanding .
I dont know what its reaction is to acetone so do a test before you start to make sure it desolves.
the white glue coat (elmers) protects the foam from the solvents in the resin
Also florist foam from a crafts store green or blue
Foam is the worst dust dont start untill you are wearing a mask only handel the 2 part or spray foam with gloves it is the worst thing you can get on your skin it dose not come off
use laminating resin vrs casting resin casting has wax in it
 

atomicjoe23

Well-Known Member
This works great. Green foam for fake flowers works the same and it's alot cheaper. sands nicer too.
I had heard this before and I know you can get it at most craft stores, but in small quantities. . .guess I need to stop by the floris and find out if I can get LARGE quantities from them or find out who their supplier is. . .
 

MARXICO

Well-Known Member
Sheets of foam are cheap at home depot check out the blue water proof stuff probly more sanding frendly ,either way you are not building a watch just get the shape close , use your energy on fiberglass and bondo work

Rember to test the foam with acetone , after you seal the foam with white glue get your shape with with bondo then glass over the bondo , when you are all finished you pour acetone on the foam and it disolves ... use a foam that disolves, then grind and sand the inside of your part

Also I found Gorilla Glue turns into expanding foam ready to sand use it for filling and touch up

Foam Cuts good with a hot wire ...heat up thin wire drag thru foam or a electric knife from the kitchen
 
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mike mcqueen

Well-Known Member
Styrofoam is for poxy. Polyurethane is for polyester. Block foam is more stable than pour foam. Speed costs money, how fast do you want to go? Do it right, You wont be sorry. MPD
 
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