From: "Bob Walker" 
To: "ATM List" 
Reply-To: "Bob Walker" 


***Warning:  I haven't tried this!***
How about making large carbon-fiber tubes by turning the vacuum-bagging
process inside out?  Lay up the CF and epoxy on the INSIDE of a nice smooth
tube with and ID equal to the OD you want your scope tube to have.  Put a
flexible cylinder inside that, and inflate it.  The pressure forces out the
excess epoxy AND stresses the form into a perfect cylinder (or at least
tends to) so it doesn't need to be especially strong. Problem: releasing
the completed from the form.  If the form is aluminum, heating it  might do
the trick since Al's thermal expansion is so much greater than CF's.  Or,
slit the form and tape it together; remove the tape after the epoxy's
cured.  This would require a stiffer form, to hold its shape during
pressurization.  Or, use two very thin slitted tubes nested with the slits
opposite...might hold its shape better.  HVAC duct might work--cut the
seams off to leave a straight, flat edge nest two of 'em and tape into
place.  It's commonly available only up to about 10" by 5' long, but a
little research should turn up bigger ones.  Details, details...

 *    Best regards,
*          Bob
         *          *    *

           *         *

--- BBBS/NT v4.00 MP