The first bamboo truss that will make up one side of our bridge is under construction in the CACC Shop.
This is one of the most important pieces of our dome because it will be supporting the majority of the weight of anyone who crosses the bridge. Because it is so important we are spending a lot of time making sure that it is right and won’t deflect as much as the original test when it is put under stress.
The first step in making the truss is to make wooden dowel inserts.
Next, we glue these into the ends of the truss web pieces. After the glue is dry we drill a hole and insert another smaller dowel. The large dowel strengthens the end of the bamboo and prevents splitting and the smaller dowel is used to lash the pieces to the top and bottom chords.
Then the web member with the dowels inserted is cut at an angle and birds-mouthed on both sides so that it fits snug to the chords.
Finally the pieces are lashed twice. Once using climbing cord to secure the pieces together and then again with recycled bike tubes to protect the joint.