RE: [ATM] Carbon Fiber for Spider Vanes

["at making" <atmaking@hotmail.com>]

Hello,

I also got some question about carbon spider vanes to, I wonder if they are 
covered by ice during cold observing session. How are they if you defocus a 
start, are air wave visibile around it ?

Frédéric Géa
http://astrosurf.com/altaz/index_e.htm


>From: "Peter" <peter@kitgear.com>
>To: "Bruce MacDonald" <brumac@gmail.com>,"ATM" <atm@atmlist.net>
>Subject: RE: [ATM] Carbon Fiber for Spider Vanes
>Date: Sun, 3 Apr 2005 16:03:23 -0400
>
>I'll eventually post how I make the vanes but since you asked I'll explain
>it here. I purchased unidirectional CF tape 5" wide 0.007" which I will
>laminate into a very thin stiff structure. The stack up is 3 layers fiber
>running the length of the vane and the two inner layers rotated by 90
>degrees. You can add more layers if you wish. The tape cuts easily with an
>exacto knife then epoxy the layers and press them overnight with waxed
>sheeting. The epoxy is squeezed out and you are left with a nice flat 
>sheet.
>
>Thanks Cord for teaching me this!
>
>Total cost for the vanes is $7.55 for the CF plus another $2 for the
>laminate epoxy.
>
>
>Peter
>
>-----Original Message-----
>From: Bruce MacDonald [mailto:brumac@gmail.com]
>Sent: Sunday, April 03, 2005 3:57 PM
>To: Peter; ATM
>Subject: Re: [ATM] Carbon Fiber for Spider Vanes
>
>
>Wow!
>I didn't know that you could get CF that thin!  That is thinner than
>the spider that came with my scope.  That particular spider has the
>opposite problem -- It is so rigid that it is not possible to shift
>the secondary by adjusting the mounting bolts.  Couple that fact with
>the fact that the tube is too thin (or not rigid enough) for its
>diameter.  What happens is that when I attempt to adjust the secondary
>position, the tube goes out-of-round.
>
>Can you divulge the source you use for Carbon Fibre?
>
>Note:  I realize that my first reply went off-list.  I'm copying this
>message to the list.
>
>--BM
>
>On Apr 3, 2005 12:44 PM, Peter <peter@kitgear.com> wrote:
> > Hi Bruce,
> >
> > I am currently planning to make 0.035" thick vanes for my 16" scope. Do
>you
> > think this is too thick?
> >
> > You and I think much a like because I used scrap strapping to make the
> > spider for my briefcase scope http://www.kitgear.com/atm/briefcase.htm. 
>It
> > is 0.025" thick but only 3/8" wide. I find this combination of width to
> > thickness not stiff enough because the secondary does rotate a bit when
> > adjusting the mirror. For a small portable scope it does OK though. Your
> > 5/8" width should  be better especially if you go for 4 vanes but you 
>may
> > want to go a bit thicker if you chose 3 vanes.
> >
> > Good choice!
> >
> > BTW - Carbon fiber is also conductive.
> >
> > Thanks for your response Bruce.
> >
> > Regards,
> >
> > Peter
> >
> > -----Original Message-----
> > From: Bruce MacDonald [mailto:brumac@gmail.com]
> > Sent: Sunday, April 03, 2005 3:34 PM
> > To: Peter
> > Subject: Re: [ATM] Carbon Fiber for Spider Vanes
> >
> > Would it not be too thick -- and therefore create more prominent
> > diffraction artifacts?
> >
> > I've just begun to experiment with this stuff:
> > http://www.signode.com/na/systems_products/sss_strapping.htm
> > It is very thin (I'm trying the 5/8" .017" thick stuff).  This allows
> > the position of the secondary to be adjusted with the secondary
> > mountings.  Also, since it is conductive, I can use two vanes to carry
> > power to my dew heater, as long as I use non-conductive mounts of
> > course.
> >
> > It also has the advantage of being considered garbage by most people
> > who have finished with it.
> >
> > What other design considerations come into play?  Esthetics?  Weight?
> >
> > --BM
> >
> > On Apr 3, 2005 10:20 AM, Peter <peter@kitgear.com> wrote:
> > > Anyone have either good or bad experiences with using CF for making
>spider
> > > vanes?
> > >
> > > Excluding cost is this a good idea or not?
> > >
> > > Thanks,
> > >
> > > Peter
> > >
>
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