Subject: Re: [harryproa] Re: low cost carbon fiber
From: "Rob Denney" <harryproa@gmail.com>
Date: 5/21/2008, 12:03 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

G'day,

We use mylar as a mould release. It works brilliantly. How do you
get it to stick to the laminate? Also, how will you get it to
compound?

There are some additives you can get for epoxy which make it very
tough (hit a casting with a hammer, nothing happens sort of tough).

Please tell us more about the paintless finish? In particular, uv
properties, application and cost.

Very glad you are going to build a proa,. Welcome to the club.

regards,

Rob

On Wed, May 21, 2008 at 11:49 PM, Raps callion
<captian_rapscallion@yahoo.com> wrote:
> That's Great! If I plan it right, I can build a carbon boat for about the
> same price of S-glass.
>
> As an aside, one thing I have been playing with at work (R&D polymer
> chemist) is increasing the impact strength of composite panels cheaply. I
> was able to increase the impact resistance of a composite panel 3X by adding
> one outer layer of very thin mylar (0.6ml). I want to try this on a carbon
> fiber panel for the hell of it. I also started playing with this paintless
> finish made by Invision which also provides a significant increase in impact
> resistance in addition to a stellar finish.
>
> Now I'm excited. I can't wait to start building a proa! and sell my laser
> 28.
>
> ----- Original Message ----
> From: jhargrovewright2 <jhargrovewright2@juno.com>
> To: harryproa@yahoogroups.com.au
> Sent: Wednesday, May 21, 2008 10:16:45 AM
> Subject: [harryproa] Re: low cost carbon fiber
>
> I simply do not understand why yahoo sometimes posts my replies as an
> attachment? Can anyone tell me why?
>
> --- In harryproa@yahoogrou ps.com.au, john h wright
> <jhargrovewright2@ ...> wrote:
>>
>> Rob,
>> This is a great post.. I have learned a lot with the pictures and
>> specifically the captions on them. You are a great resource for
> those of
>> us that do not have your extensive professional background.
>> john in bastrop
>>
>> On Wed, 21 May 2008 22:06:25 +0800 "Rob Denney" <harryproa@. ..>
>> writes:
>> G'day,
>>
>> The cheap way to buy carbon is as tow, which is the individual
> bundles
>> of filaments used to weave cloth or uni. I use very thick (50,000
>> filaments, 200 gsm/6 ounce cloth is 3,000) tow which gets a lot of
>> carbon down quickly.
>>
>> There are 270metres of tow in a kg, so a meter weighs 3.7 grammes,
>> which is near enough 1.1 ounce, so you need 5 pieces a foot long to
>> get 5,5 ounces per sq foot. Use a wet out machine (see pictures at
>> http://www.harrypro a.com/building_ Vis/building_ Vis_5.htm does not
> have
>> to be this large) and pull it through 10 or 20 pieces at a time and
>> lay it straight on the job. There is no lengthwise cutting required,
>> and no waste.
>>
>> If you prefer unidirectional, it is available in 200, 300, and 900
>> gsm/6 ounce, 9.5 ounce and 20 ounce, any width you like. Costs twice
>> as much per unit weight as tow. Two layers of this at 90 degrees to
>> each other is about 60% cheaper than double bias or biaxial.
>>
>> Carbon is essential in a reasonable size unstayed mast, makes a lot
> of
>> sense in rudder shafts, reasonable sense in beams and sense in hulls
>> if you want the ultimate light weight. Generally speaking, you use
>> about half the weight of carbon (and resin) as glass in a hull, but
>> there are other considerations such as impact resistance, water
>> proofness, etc if it gets too light. To use carbon without a vacuum
>> bag is pretty much a waste of money as there will be more resin (and
>> maybe air as well) than necessary, so the job is heavier.
>>
>> Any specific questions, let me know.
>>
>> Regards,
>>
>> Rob
>>
>> On Wed, May 21, 2008 at 12:09 AM, captian_rapscallion
>> <captian_rapscallio n@...> wrote:
>> > --- In harryproa@yahoogrou ps.com.au, "Rob Denney" <harryproa@>
>> wrote:
>> >>
>> >
>> > pardon my ignorance, how much does the fabric weigh per unit
> area? Is
>> > it biaxial? Unidirectional? I would use carbon if it meant a
>> > noticeable increase in speed. I would just be a bit concerned
> about
>> > impact strength. Perhaps a very light layer of kevlar or vectra
> would
>> > help?
>> >
>> >> G'day,
>> >>
>> >> Cost varies on where you are and how much you want. Small
> amounts are
>> >> $Aus45 per kg, plus freight.
>> >>
>> >> Regards,
>> >>
>> >> Rob
>> >>
>> >> On Tue, May 20, 2008 at 2:28 PM, captian_rapscallion <
>> >> captian_rapscallion @> wrote:
>> >>
>> >> >
>> >> >
>> >> > Rob,
>> >> >
>> >> > I was hoping to get more info on your low cost carbon fiber.
>> >> >
>> >> >
>> >> >
>> >>
>> >
>> >
>>
>
>
>

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