Date:         Sat, 8 Sep 2007 00:00:34 -0400
Reply-To:     David Milo <dellaone@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Milo <dellaone@GMAIL.COM>
Subject:      Re: Carbon fiber van tops...?
In-Reply-To:  <549267.35772.qm@web52508.mail.re2.yahoo.com>
Content-Type: text/plain; charset=ISO-8859-1

Okay Okay,

What then, do you see as the perceived advantages of carbon fiber over the
fiber glass construction of the conventional pop top?

Aside from the fact that the aerodynamic drag will be the same if designed
the same, are you anticipating that it will save you 100 pounds of weight?
Do you know what an average existing pop top weighs? (I do, and the cost to
benefit ratio isn't there).

I've been to a training course on composites in Reno Nevada, very neat stuff
and lots of options available to meet specialized design requirements
(graphite, Kevlar etc,) but fabrication with the materials involved
generally requires a kiln and age and temperature control on the raw
materials (adding to the cost).

Plus, it is generally nasty to repair, it still needs specialized knowledge,
a kiln and expensive materials (try to find a carbon fiber repair kit at
NAPA) to perform properly, and can cause lung damage if the proper
precautions aren't taken when working with it, (even simple stuff like
drilling through it to add whatever, roof racks etc).

Yes, a carbon fiber bike frame is very light and strong, but also very
brittle, and expensive (or impossible) to repair locally.

I'll pass.

Dave

On 9/7/07, Chris S. <mrpolak@yahoo.com> wrote:
>
> Live it to the list to tear any idea to shreds.
>
> Your pricing MIGHT be a little off.  You can get carbon fiber hoods for
> about $800.
>
> Max Wellhouse <maxjoyce@IPA.NET> wrote: $500?  The last time I checked,
> graphite cloth in a 6 oz, weight was
> selling for about $75/yd.  I don't remember if that was 38"wide cloth
> or 60", but the fact of the mater is that you're looking at maybe 3
> layers minimum to make that top stiff enough unless you took some
> sort of foam core stiffener and that carbon top would likely not
> survive much of a hail storm either.  The foam core stuff ain't cheap
> either. d.  Something with that many convolutions would almost have
> to be vacuum-bagged and I'd want a couple of layers of kevlar under
> the foam core just for strength. The kevlar is a bargain at like
> $15-18 a yard if you get it from www.sweetcomposites.com  Then
> there's the cost of making the mold for the top after you make the
> male plug to make the mold from.  The Westy top wouldn't be rigid
> enough to mold.
>
> Let's see, that first carbon top would cost about $12,000, and the
> next one maybe only $2,000 if you di all the work yourself.
>
> DM&FS
>
> At 10:34 PM 9/6/2007, Don Hanson wrote:
>
> >a Van top from carbon fiber, while it would be very trick, from a
> practical
> >standpoint makes little sense.  Unless you're Bill Gates or Jay Leno or
> >someone with lots of money to spend on a questionable project.  The
> amount
> >of material you'd use to make the part...fiberglass or carbon fiber.. is
> a
> >lot.  Glass fabric is a little heavier and not quite so stiff, but it is
> >about 1/100th the cost of carbon fabric..In a piece as large as a Westie
> >style roof, you might save oh, say 20-30 lbs, by using carbon fiber
> rather
> >than the normal glass,  but you'd probably spend $500 doing it...You
> could
> >save almost that much weight just by vacuum-bagging a fiberglass lay up
> and
> >being very careful with the fabrication..
> >   Now, in a racecar or a bicycle or an America's cup yacht or an
> >airplane...that kinda dollar per lb. may be worth it..but for the top of
> a
> >Vanagon?  Prolly not to normal humans...
> >   Don Hanson
>
>
>
> ---------------------------------
> Pinpoint customers who are looking for what you sell.
>