Sunday, February 12, 2012

Building carbon fiber tubes... How I did it...

The handcycle requires quite a few tubes for the steering and hand grips (pedals).  My initial method failed, but the next attempts worked out quite well.  Now, it is almost second nature for which I can build in tube in literally a few minutes.

Carbon fiber tubes can be purchased online.  They are usually quite expensive.  The larger tubes are often quite long (50", 60" for instance).  Well, I don't need the length -- nor the expense.  Usually, I just need a few inches of tube.

Here are some of the supplies:

(Do note that may plastic pipes are not "round".  Therefore, I would not use plastic pipe as a mandrel for longer tubes)

I select a pipe or tube (whatever I can find) that matches the inside diameter of the tube that I am constructing out of carbon fiber.  That is my mandrel. The steps:

  • Put a light coating of grease (or mold release) on the mandrel/pipe that represents the inside diameter of your new tube.
  • Wrap the mandrel in plastic food wrap to cover the grease.  I have not tried it with mold release agent, but that may work.  If the tube is long (8" tube is my longest), then the twisting the new carbon fiber tube off the mandrel takes some elbow power. For me, the grease worked very well as compared to other agents.
  • Calculate the thickness of tube that you desire.  I usually figure 10 to 15 layers.  Therefore the outside diameter is adjusted by 20-30 layers of carbon fiber.  Depending upon the thickness of the carbon fiber, then outside diameter will be approximately 1/4" (or more) greater than the inside diameter.  I usually figure a layer of carbon fiber with epoxy at 0.015" of thickness for the 5.8 ounce fabric.
  • Wet down the carbon fiber.  I usually do this on a flat sheet covered with a piece of plastic sheet.  The plastic sheet is throwaway after using it a number of times.
  • Wrap the mandrel with the carbon fiber.  As I wrapped the carbon fiber I pull the mandrel back while holding the other end of the carbon fiber stationary -- thus tightening the wrap.  This works very well in causing a tight rolling of the carbon fiber on the mandrel.
  • Wrap the finished carbon fiber in peel-ply -- in the same direction as the rolling of the carbon fiber.  After the peel-ply is fully wrapped around the carbon fiber covered mandrel, keep pushing the peel-ply around with the hands while twisting the mandrel in the opposite direction. This will keep tightening down the carbon fiber.  The excess epoxy will start leaking out in quantity.  I was quite surprised at how well this worked in removing excess resin and causing a tight compression of carbon fiber.

  • After the epoxy cures (I usually wait about 6-7 hours with the 205 Fast Hardener), twist the tube off the mandrel with your hands.  It takes some elbow grease for longer tubes. After the initial movement of the tube on the mandrel, the tube will twist off more easily.  Sometimes initiating the movement is difficult.
Here is the results of one group of tubes (the ends of which will be cut off):


  1. hi coo l stuff i got some Q for you some time hope you camn help Lee

  2. Thanks for sharing the information about Building carbon fiber tube. Really a great blog which provides all valuable information!!

    Carbon Fiber Rods