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How to Mold a Carbon Fiber Frame

Carbon fiber is a composite system similar to fiberglass. It uses carbon fiber mesh primarily as tensile strength and polyester resin to give it structure. There are myriad ways to manufacture and mold carbon fiber frames, including bicycle frames. They include vacuum molding; inside/outside molding, where a form is used on each side of the carbon fiber; and bladder forming, where a bladder presses from inside a component, out towards the mold. To get started in carbon fiber frames, make them the way you'd make steel frames, using a jig, a purchased carbon fiber tube and two-part epoxy instead of welding or brazing, hand molding the joints.

Things You'll Need

Manufactured carbon fiber tubing
Wood or metal frame jig
Tube cutting jig
Rotary tube cutting mill
Half-round file
Nylon pipe clamps
Metal epoxy
Carbon fiber mesh
Two-part resin

Instructions

- 1
  Construct a jig that will hold each of your frame's tubes at the precise angle they need to be. You can draw your frame geometry on a sheet of plywood, then screw blocks of wood with V notches cut into them to cradle the tubes, positioning one cradle to hold each tube at the appropriate angle and height of the plywood jig.
- 2
  Use a tube shaping jig and cutter to cope the joints of your carbon fiber tubes, so they will plane into one another accurately at each joint. Reference your template for the angles at which the tubes plane together. Your cutting head must be the same diameter of the tube the piece you're cutting will plane into, and the cutting heads have to be very high quality, such as cobalt or tungsten carbide as carbon fiber is quick to dull blades.
- 3
  Set each frame member in your jig, once the joints have been coped. Take them out and fine tune the joints slightly with a sharp, half-round file. Ensure your tubes are properly aligned and secured in place with nylon pipe-clamps or other clamps that won't scratch or crack the carbon fiber.
- 4
  Epoxy each joint in place using a two part epoxy suitable for cold-welding metal. Build up the epoxy around the joint where you would make a braze or weld, keeping in mind, the excess will be filed down. Allow the epoxy to thoroughly dry making absolutely sure the joints are not disturbed as they harden.
- 5
  With a sharp rounded file and or rotary tool, shave the excess epoxy from the joints, leaving a concave deposit of epoxy as if you had caulked around the area and wiped it away with your finger.
- 6
  Brush two-part resin over one of the joints, then lay a small patch of carbon fiber over the wet epoxy, working additional resin into the carbon fiber and smoothing it as you go. Continue placing patches of carbon fiber cloth around the joint, first wetting the base, then infusing the mesh and working out any air bubbles. Each joint should effectively receive a carbon fiber sleeve to hold the epoxied joint in place as well as provide rigidity to the joint.

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