MOULDING A KIT COWL ??
02-28-2004, 10:41 PM
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MOULDING A KIT COWL ??
Whats a cheap and quick way to take a mould off a kit, engine cowl. Ive tried plaster of paris, but had problems....anyone got a system that works. I dont want to go the fiberglass and epoxy route????? [
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03-04-2004, 07:36 PM
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RE: MOULDING A KIT COWL ??
there really isnt an easy way to do what your looking to do. there are however several methods to mold a new cowl from an existing one, each method having varying degrees of difficulty and involvement. Im a college student majoring in Industrial technology with a plastics/composites focus ad have had to work with this sort of thing a bunch of times now.
1) you can make a fiberglass mold of the original cowl and make replicas from that. This way is probably the most involved and time consuming but will also give the best results if you put the necessary effort into it.
2)you can make a plug by filling the original cowl with some sort of hardening material like plaster of paris or bondo, however, the pressure of the material filling the cowl can deform the cowl giving you a plug that is distorted compared to the original.Whatever you use, dont forget to use a mold release compound on the surfacees of the cowl that come in contact with the filling compound(especially important with something like bondo). If you use plaster of paris there are a couple things that you can do to get better results. First, rather than mixing the plaster with just plain water, you can mix a rubberizing agent in with the plaster, Ive used a white glue called Weld Bond with good results. The Weld Bond when dry remains somewhat flexible and will help to prevent the plaster from chipping and cracking when you remove it from the cowl. Also because plaster of paris hardens because of evaporation youll have to fill the cowl in stages rather than 1 big pour. If you use bondo there are a few things to consider here, first is that bondo is a polyester resin system which can attack the plastic material of the cowl ruining everything. Also bondo cures chemically, that chemical reaction generates a good amount of heat and when in a large enough volume can get hot enough to melt the plastic cowl. So obviously filling in stages is needed here too.
3)from the plug youve made the best option for making cowls is thermo-forming, for this youll need appropriate sheets of plastic material, a frame to hold the sheets while heating them, a way to heat em, a vacuum table to hold the plug and draw the soft hot plastic down onto the plug before it cools.
I can go into specifics if your interested in any of these options. your best bet is to drop me an email about it or IM me at pilotx1 on AIM
1) you can make a fiberglass mold of the original cowl and make replicas from that. This way is probably the most involved and time consuming but will also give the best results if you put the necessary effort into it.
2)you can make a plug by filling the original cowl with some sort of hardening material like plaster of paris or bondo, however, the pressure of the material filling the cowl can deform the cowl giving you a plug that is distorted compared to the original.Whatever you use, dont forget to use a mold release compound on the surfacees of the cowl that come in contact with the filling compound(especially important with something like bondo). If you use plaster of paris there are a couple things that you can do to get better results. First, rather than mixing the plaster with just plain water, you can mix a rubberizing agent in with the plaster, Ive used a white glue called Weld Bond with good results. The Weld Bond when dry remains somewhat flexible and will help to prevent the plaster from chipping and cracking when you remove it from the cowl. Also because plaster of paris hardens because of evaporation youll have to fill the cowl in stages rather than 1 big pour. If you use bondo there are a few things to consider here, first is that bondo is a polyester resin system which can attack the plastic material of the cowl ruining everything. Also bondo cures chemically, that chemical reaction generates a good amount of heat and when in a large enough volume can get hot enough to melt the plastic cowl. So obviously filling in stages is needed here too.
3)from the plug youve made the best option for making cowls is thermo-forming, for this youll need appropriate sheets of plastic material, a frame to hold the sheets while heating them, a way to heat em, a vacuum table to hold the plug and draw the soft hot plastic down onto the plug before it cools.
I can go into specifics if your interested in any of these options. your best bet is to drop me an email about it or IM me at pilotx1 on AIM
