Aero Ply Help

[quasi]

I'm making a cylindrical shape out of aero ply and i was wondering how i could get it to bend into the cylindrical shape. do i need to use a bag press or make supports for inside of the cylinder?
please bear in mind this is for GSCE level.
Thankyou x

[Durdge39]

What thickness is the ply, and what's the diameter of the cylinder you want to make? This will determine how much support strength is required to keep the ply in the cylindrical shape, also to determine if the desired shape is within the limits of the ply. Aero grade ply is good, and quite ductile, especially the thin stuff, but trying to make too smaller cylinder from too thick ply will result in lots of splintering.

Will people be able to see inside the cylinder and should that be framework free for aesthetic reasons? If not, then ply disks, or circular framework would be the way to go. This would be simple and relatively strong.

Getting a perfect cylinder without any internal framework will be mighty troublesome, as you need a great deal of support on the seam to avoid the spring of the ply from turning it into a tear-drop shape. Unfortunately, wood doesn't hold its bent shape unless one steams it or treats it in a similar way. This springing has the most power at the seams, as there is nothing on one side of them to have leverage upon them and keep them bent, like the middle of the piece does.

Depending on above conditions, I would try to overlap the seams about 1/5 of the circumference or your cylinder and either thoroughly glue it, or glue it and also use some wide pressure spreading through-fasteners (screws with dished washers or the like) if it is thick ply. Thin ply would likely only need glue.

You could also taper the edges to make the cylinder walls a uniform thickness, this will also assist in making the seams that bit easier to bend and fixate.

Below is my highly technical diagram (:D) of what is circling around in my head.

http://www.durdge39.com/images/plywoodseam.jpg

All the best with it!

Tom.