Fiberglass experience anyone?

[Crue]

Last winter I had a chance to try my hand at boddy work a bit on the old fiero. The ground effect were really damaged by the previous owner. It was a fun project and it turned out really well according to the mechanic that works on the car for me. I was thinking of trying to build a small fairing to mount on the front of the bike and was wondering if anyone has any tips on building a mold. I need to know what materials to use. I think it would be a fun project to try and the cost of the fiberglass and bondo aren't much. I already have some adjustable mounting hardware I kept from a friends windshield he ruined last year. I really like the Corbin trim tab on the VTX 1800neo below and would like to try to make something similar although not as bulky. Any thoughts?

[zedx11]

I haven't done any work like that for years and even then it was not much but, I used to have a link for a site that you could order all the stuff to do it out of carbon fibre. I'll find it again sooner or later.

[Crue]

Post it when you find it.

[zedx11]

I sure will.

[Fixion]

I recommend you make a plug first, make the mold off that, then make your final part. It will look much better.

You can get sheets of 2" foam from Lowes (blue or pink, doesn't matter), cut those up and make a big foam block that is roughly the shape/size you need, then start cutting and sanding.... Then bondo it up, sand, and repeat until you have a nice plug, then lay up your mold on that.

[Portman7]

What you use?
windows xp
windows 2000
windows 98
windows 95
or other

---------------
Thanks

[4W4K3]

Originally Posted by Portman7

What you use?
windows xp
windows 2000
windows 98
windows 95
or other

---------------
Thanks

Huh?

[Crue]

Fixion after I make a plug from foam what do I lay over it to keep the fiberglass from sticking to the plug?

[zedx11]

if you do a google there are sites that tell you all about it. I just had a site that told about how to and sold the materials.

[BigJohn]

Originally Posted by Crue

Fixion after I make a plug from foam what do I lay over it to keep the fiberglass from sticking to the plug?

Crue - after you make the plug there are several ways you can go.

1) Wax it using something like candle wax or something similar, or
2) (I think) use a commercial releasing agent.

After you have the wax/release agent/whatever on, Then you can make the mold. Make sure that you include a brake line and some form of flanging so that you can split the mold when you make the final product.

Alternative would be to use the "plug" as the shape/form and create a composite piece. It's the same process as used by experimantal aircraft builders. Basiclly, carve and sand the shape, glass over it, then sand and fill using a slurry of thin exopy and microsphers. Then sand, sand, sand....until you are ready to paint.

You can find a good expliantion at:

http://exp-aircraft.com/library/alexande/composit.html


John

[zedx11]

here it is man, everything you need to know.

http://www.fibreglast.com/contentpag...enter-283.html

[zedx11]

Fibreglassing Fundamentals

Practical Aspects of Hand Lay-up

In this class we shall cover the basic procedures to be used in laying up a composite by hand using cloth (woven and/or chopped strand mat) and liquid resins. First some terminology..

Terminology
Piece : The finished product that you are making, a kayak or sailboard, for example.

Mould : The thing from which the piece is fabricated. The mould from which you would fabricate a kayak will look very much like a kayak except that it will be smooth on the inside. The inside of the mould will be duplicated on the outside of the piece.

Plug : When the mould itself is constructed from fibreglass, the starting point is the plug. The mould is constructed from the plug. The plug, used to construct a kayak, will look exactly like a kayak on the outside. However, the plug can be constructed from anything so long as it has a smooth non-porous surface.

Laminate : A solid constructed of successive plys of resin and fibreglass.

Ply : A layer of cloth impregnated with resin and allowed to cure (set). Most structures are fabricated from several plies, the plies may have the same or(more usually) different orientations.

Gel Coat : The outer-most surface of the mould or piece, its purpose is cosmetic. It gives the piece and the mould the colouration, finish and durability desired. The gel coat consists of a thin layer of specially compounded resin.

Mould Release : The material used to effect a release between a mould and the moulded part.

Cure : The process in which the liquid resin becomes a solid and bonds to the fibres. This is a chemical reaction between eith different components of the resin or between the resin and a hardner. The cure can be effect by heat or the addition of a catalyst.

Fundamentals of Polyester Resin systems, Including Gel Coats
The curing mechanism of polyester resin is inhibited by air. Therefore if the resin is exposed to air for a considerable time, the surface may remain sticky for several weeks. If the coat is cured rapidly, as in a thick laminate, inhibition will not occur because of the heat generated by the curing reaction. However, when applying thin films of polyester resins, such as surface coats, it is necessary to add styrene wax to the resin to obtain a full cure. The wax rises to the surface during the cure and can be later removed with soap and water.

Wax does not need to be added to gel coats applied against the mould as subsequent layers prohibit air inhibition. Wax is only necessary when the gel coat is exposed to air.

Building The Plug
The plug may be constructed of nearly anything. It is the surface finish that is important. Quite often it is desirable to merely reproduce, in fibreglass, an item already on hand. In such a case the item already on hand will serve as the plug.

In most cases, the plug is constructed from scratch from some easy to work with medium. An ideal medium is styrofoam or polyurethane. In these cases the plug must be coated with an epoxy resin rather than a polyester resin (just watch the styrofoam dissolve). After sanding the plug smooth coat with a thin layer of resin and cover with a layer of 35gm/sq.m

(1oz/sq.yd) glass fibre cloth. After drying brush on several thin layers of resin, sanding between layers. The surface finish at this point is the most important.

Mould Release
Mould release must be applied to the plug - this is an important step in the process. If the release agents fail to

perform the mould will not release from the plug and many hours will be required to fix the damage and develop a smooth surface with the desired geometry. The usual method of applying mould release is 3 layers of carnuba wax. Each layer should be left to dry fully 1-2 hours then buffed to a shine. This is followed by a light coat of PVA film either sprayed or brushed on. Allow to dry overnight before applying the gel coat.

Gel Coat
The gel coat is the first step in making the actual mould. The gel coat should be applied in two coats of 0.4mm (.015") each, allowing 1-2 hours between coats. The gel coat should be tacky but not wet before proceeding. Use MEKP (MethylEthylKetone Peroxide) hardener at 2% by volume with polyEster gelcoats.

Gel Coat Troubleshooting

Application of the gel coat is perhaps, the most difficult aspect of manufacturing in fibreglass. Problems arise due to temperature variation, catalysing and a variety of handling techniques. The following list should help resolve some of the difficulties.

Wrinkles and Pinholes
A coating less than (0.005") thick may wrinkle especially when brush marks are present. The preferred thickness is 0.25mm (0.010") to 0.5mm (0.020"). A wrinkle can also occur if the gel coat is not cured enough prior to lay-up. Before lay-up check the surface for tack. The surface should be sticky but not transfer to your finger. Several things can affect a slow cure; solvent or water entrapment, undercatalysation and cold temperatures. If the gel coat contains pinholes, check the spray equipment for moisture in the air lines or dirt in the traps.

Slow Gel Coat Cure
Any temperature below 21°C (70°F) will retard the gel time. An under-catalysed gel coat will result in a slow cure but
this is not a recommended technique for deliberately lengthening gel time. The usually ratio of initiator (MEKP) to Polyester Resin is 2% by volume. High moisture and humidity will lengthen gel time.

Sagging of the Gel Coat
The most common reason for the gel coat to sag is because the application was too heavy. To avoid this, spray in multiple light applications from about 15" distance from the mould. The maximum application to be sprayed at on application is 0.4mm (.015").

Porosity
Gel coat porosity (air bubbles) is normally caused by trapped air or moisture. This can be prevented by limiting the gel coat application to about 0.1mm (.005") per pass. Avoid excessive air pressure, 40 -80 psi is adequate depending on resin viscosity.

Blisters When Immersed in Water
Blisters are caused by an incomplete cure, improper wetting of the backing fibres, a bad bond between the gel coat and the back up laminate (Usually due to grease) or too thin a gel coat.

Lifting of the Gel Coat before Laminating
This is caused by shrinkage of the gel coat because the coat cures too fast because of over catalysation, delays between application of the gel coat and laminating or the mould surface is too hot (usually the mould has been in direct sun light and is over heated.

Back up Pattern Showing
Gel Coat is too thin or was not sufficiently cured before laminating

Gel Coat sticking to the Mould/Part
This condition is caused by improper releasing of the mould surface. Must use release agents developed for the fibreglass industry.

Laminating
Once the final layer of gel coat has been allowed to dry for several hours the skin lamination may be applied. For making the mould use a lightweight glass cloth, about 25gm/sq.m (0.75 oz/sq.yd). Apply a coat of moulding resin and gently lay the mat into the resin. Careful cutting of the cloth may be necessary to ensure conformance to the surface of the plug.

Use a stiff bristle brush to force resin into the cloth and to make it conform to the various contours of the plug.

Dabbing is better than brushing, A short mohair roller is good for long gently curving surfaces. All air must be worked out so that the matt is tight against the plug surface. Allow 2-3 hours to dry before proceeding with the next layer of the lamination using a 50gm/sq.m (1.5 oz/sq.yd )cloth. This should be followed up immediately with a 350gm/sq.m (10oz/sq.yd). fabric. The mould should be built up such that its final thickness is about 2 to 3 times that of the parts that are to be produced from it. One the heavy fabric layer has been allowed to cure for about 3 hours a combination of woven roving or chopped strand mat under a 50 gm/sq.m (1.5oz/sq.yd) cloth can be added to build up the required thickness.

Use MEKP hardener at 1% by volume with polyEster moulding resin.

Removing the Mould
Allow the completed mould to cure for 48 hours before attempting to remove it from the mould. Care and time are required to get the mould off the plug. Soft plastic wedges can be driven in between the plug and mould to facilitate the release.

Once free of the plug, replace the mould on the plug and add bracing to the mould using wood or metal to prevent distortion of the mould. Wait 24 hours before removing from the plug. The mould edges should be trimmed and the PVA washed out with warm soapy water. Any wrinkles or air bubbles in the gel coat should be filled and sanded plug to the mould at this time.

Moulding the Piece
Once the mould has cured for at least 72 hours you are ready to apply the mould release wax and PVA parting film exactly as was done when preparing the plug. Apply one 0.5mm (.020") layer of pigmented gel coat as before, waiting the 2 to 3 hours before continuing with the laminations, employing the same technique and care as used in preparation of the mould.

[zedx11]

Safety Considerations
Styrene, the solvent and cross-linking monomer used in polyester resins is a highly volatile and dangerous substance, being both flammable and toxic when inhaled. Styrene will act as a solvent for the fatty tisues of the lungs and results in liquation (drowning) of the interior of the lungs - symptoms are similar to tuberculosis. Work in a well ventilated
area only - the great outdoors is perhaps best - but avoid direct sunlight. Use a respirator capable of absorbing organic vapours. Do not have any open flames anywhere near the resin as combustion will be instantaneous. Remember that the temperature must remain above 20°C (75°F) for 24 hours to allow for proper curing. If you must work indoors use a bagging system to contain the vapour during curing.

Fibreglassing Polystyrene Foam
The two most common types of foam are expanded or pre-expanded polystyrene foam. Expanded polystyrene foam is commonly used in the building industry as an insulation material while pre-expanded foam is used as a packaging material. It is often desirable to apply a skin of durable fibreglass to these foams, however, both are dissolved by the more common and inexpensive polyester resins and as such the more expensive epoxy resins must be used instead.

Materials
Fibreglass cloth comes in many varieties. The most commonly used in skin laminations are:

Epoxy resin is a two component, low viscosity epoxy system for applying a skin lamination. The normal mixing ratio, #88 Epoxy resin to #87 Epoxy hardener is 5:1 epoxy to hardener. Colour pigments can be added to the epoxy resin system. The best way to apply the resin is to use a short nap paint roller for both the priming coat and saturating the cloth, finish coats are best applied with a good quality nylon paint brush.

Methods
The temperature must be above 23°C (75°F) for at least 24 hours after application. Work in a well ventilated and dust free environment - avoid direct sunlight. Always add the hardener to the resin and mix well before applying. The surface to be fibreglassed should be clean and dust free - a fine grit sandpaper will suffice. Do not use chemical cleaners other than household detergent as they will attack the foam.

Prime Coat
A litre of resin will cover about 3.5 sq.m (35 sq. ft). The initial application should be thick, but not too thick as to cause runs or sags. Allow to dry for several hours before applying the glass. Resin should be mixed in small quantities e.g. 100ml of hardener to 0.5 litre of epoxy resin. This will last about 15 minutes before it hardens.

Glass Cloth
Cut the cloth so that it more or less conforms to the surface to be covered. Final trimming should be done while saturating the cloth. Apply a thin coat of the mixed resin to the surface and immediately cover with the glass cloth.

Smooth out the glass cloth. Apply additional resin to the glass cloth so that it is fully saturated and transparent. Make sure there are no blisters, air pockets or dry areas. If more than one piece of glass is used, make sure each is fully saturated before proceeding to the next piece - alloy about 2.5cm (1") overlap between adjacent pieces.

Allow 24 hours to cure. Sand out any laps, seams or other surface regularities with a 100 to 220 grit sandpaper.

If a colour pigment is to be added to the final coat it is a good idea to slightly tint the glass layer. use about 1 teaspoon (5ml) of pigment per 250ml of resin.

Finish Coat
If colour pigment is used add at the rate of 1 teaspoon (5ml) to 250ml of resin. Mix all the resin you will need at one time to avoid any variations in coloration. Thixotropic silica can be added to prevent sags and runs at the rate of 75ml of silica to 250ml of epoxy resin - allow about 10 minutes to thicken - before adding the hardener.

Source: http://callisto.my.mtu.edu/my4150/class20/class20.html



Carbon Fibre Panel Building - Sir HSV

Another way you could construct a case is by using CarbonFibre, Carbon Fibre parts are everywhere these days, but in case modding? i have not seen any case use it yet.

Constructing the case is simple.

Building the case

Deciding on the case design is up the individual, but for this example we will stay with the more common rectangle shape.

Grab yourself some Balsa wood from your nearest hobby supplier, the best thickness would be around 2mm.

Glue your panels together and take your PSU, PCI slots etc into consideration when building it, although any changes can be made to the design while it is still in the planning and building stage.

Once you have constructed the case you will need to seal it, first thing to do, is to give the case a good sanding using light sandpaper, using harsher sand paper on balsa wood will leave deep lines and scratches.

Once you have sanded your peice down you will need to seal both sides of the Balsa wood using fibreglass resin.

To get the right mix of resin, mix a 1:5 mix ratio of hardener and resin. Stir the epoxy resin slowly so you do not get any unwanted air bubbles. If you got the ratio right you have an effective work time of about 20 minutes before the resin starts to cure, so working fairly quickly is a must.

Measure your carbon fibre sheet over your Balsa wood case, this is important to ensure you have enough carbon fibre matting to do the job, once you have enough, lay your carbon fibre matting down on a waxed surface or polyester film.

Lay down a good layer of resin with a brush, allow this to harden alittle and lay down your sheet of carbon fibre on the outside.

Take into account you will need to leave enough overhang as carbon fibre tends to fray alittle, cut the excess off but allow 5mm - 10mm overlap.

Lay this down and spread it out evenly and allow it to harden, lay down another top cover of resin, allow this to sink into the matting, you can give this a light sanding and then lay down a better cover of resin and sand this to a gloss finish.

The inside of the case you can also line with resin or carbon fibre to add extra strength!.

If you are adding a side window and would like a carbon fibre finish, the line both sides of the Balsa wood with carbon fibre and give the outside part of the window an extra coat of resin to give a gloss finish.


'slip moulding' - Sir_HSV

Slipping or Slip moulding is more common with pottery or china moulding, but the same principal can be used with fibreglass resin as well.

If you are after a particular shape or want a re-production of something why try this?

In this example we are using a car shape:

Simply get the body your after, whether it be Ferrari, Chev Lumina, HSV GTS Monaro, whatever.

1/10th scale polycarbonate bodies are pretty cheap and totally clear, although i would not recommend modding one as the layer of polycarbonate is way too thin.

Buy some PVC and line the inside of the body (same way you would for fibreglass), then as you would for fibreglass, line the inside with resin (only), build the resin up slowly until you get a nice thick wall, when dry seperate the polycarbonate body away from the resin.

You should be left with a resin re-production of the polycarbonate body.

This should now give you something to work with, you can dremel (wear a mask and glasses but more importantly the mask prevents the dust from getting into your lungs) till the cows come home!.

This would be one way, there is another using rubber latex to make a mould of the body from the outside, or you can try using plaster to take a mould of the body, but the problem with plaster is always going to be air bubble, and several may to be done to finally get a good mould without bubbles.



Hope this helps someone ...



Sir_Hsv


Edited by Sir_Hsv: 19/4/2004 2:40:27 PM

[Crue]

Thanks for the info guys I think I have everything I need to tackle the job. Should be fun, hope it turns out okay.

[Fixion]

Originally Posted by BigJohn

Crue - after you make the plug there are several ways you can go.

1) Wax it using something like candle wax or something similar, or
2) (I think) use a commercial releasing agent.

After you have the wax/release agent/whatever on, Then you can make the mold. Make sure that you include a brake line and some form of flanging so that you can split the mold when you make the final product.

Alternative would be to use the "plug" as the shape/form and create a composite piece. It's the same process as used by experimantal aircraft builders. Basiclly, carve and sand the shape, glass over it, then sand and fill using a slurry of thin exopy and microsphers. Then sand, sand, sand....until you are ready to paint.

You can find a good expliantion at:

http://exp-aircraft.com/library/alexande/composit.html


John

Spray paint it so that it's nice and glossy, put on a layer of mould release, wipe it off, repeat this about 3 times and then spray it with a couple layers of PVA mould release (like 6). If don't want to get PVA, then juts put on more mould release I guess. Then you want to lay up your mould on the plug, use ALOT of fiberglass, fine weave at first, then some heavier stuff, you can add popsicle sticks to make it more rigid or something similar. You want to make the mould as rigid as possible. Vacuume bag it if you can, otherwise just make sure you do a good job (I guess... you may have to fix bubbles latter). Once the resin cures, separate the edge of the mould from the plug, cut the edges off if you have to (make sure you have a bigger plug than you need around the edges ), if it sticks, use an air compressor and blow air in-between the mould and the plug. If you have to force it off even more than that, you may damage the plug... which you can usually fix without much pain... (if you ever need to use the plug again).

Then lay up your final part on the mould the same way as you did with the plug, but you probably don't want to make it as heavy.

Ummm.... that's about it I guess.

EDIT: I forgot to mention you'll need a paint sprayer for the PVA, and you apply very light coats, you don't want it to run, otherwise you'll have to start over.

If you have access to an oven, a freezer, and a vacuum pump (and some money) you may want to try preimpregnated carbon fiber. It's much easier to work with . But that could get a little expensive since prepreg carbonfiber is like $50 a square yard.

[ispeed77]

Originally Posted by Crue

Thanks for the info guys I think I have everything I need to tackle the job. Should be fun, hope it turns out okay.

as usual, keep us posted ! good luck with it.