Step 8: Getting Started
Let's get some bamboo and get started. There are 1600 varieties of bamboo and a lot of them would work. I ended up using a timber variety called Blue Hennon. My choice was based on what others had used successfully for their bikes and conversations with bamboo nursery staff. There is a lot of variety between species in wall thickness and rigidity so investigate a bit. You can buy Blue Hennon on ebay from Charlene (AKA rainbowsatoz). I purchased my bamboo from her and was very pleased. http://myworld.ebay.com/rainbowsatoz/ She is also the person "Bamboobiker" bought from and how I found her on ebay (http://www.instructables.com/id/Bamboo-Bike-2/). I also used the same resin as "Bamboobiker" -- Max CLR hp (pic 2) -- which you can buy here -- http://myworld.ebay.com/polymerproducts/. Since I knew so little about carbon fiber, epoxy resins, etc, I went with Bamboobiker's suggestions and was very happy. A lot of good info in his Instructable!
The first step to preparing the bamboo is puncturing the nodes inside the bamboo to allow air to escape during heating. When my bamboo arrived, I broke every node or diaphragm in every piece so I wouldn't have to worry about it later. You can break it with a metal rod or drill it out with a long (36") electrician's drill bit. Puncturing the nodes allows air to escape when you are heat treating the bamboo. If you do not break the nodes, there is no place for the trapped air to expand to and the bamboo will explode. Do this step first on your pieces and you won't have to worry about having an accident. From what I've heard, it's not something you'll do twice.
Next is to heat treat the bamboo which caramelizes the sugars in the walls and makes the culm harder and stronger. You need a regular propane torch to gradually heat the bamboo over a fairly large area. You'll also need leather gloves, safety glasses, and old bath towels or rags. It takes a lot of heat to accomplish this step and a hot air gun isn't enough to do it efficiently. I typically heat the bamboo until the waxy outer layer becomes shiny (pic 2) and wipe off the wax. Repeat this step until the pole looks dull and then continue heating a smaller area about 3-4" long all the way around. Suddenly the bamboo will switch to a brown color (pic 3) and you want to continue heating where the green and brown bamboo meet each other until the entire culm has been heat treated. You will be able to shade the bamboo darker or lighter as you go along. Since you'll be sanding the outer layer off it's best to go a little darker than you want your final color to be. I prefer to heat treat all of the bamboo before I start so it's ready to go. The other option is to cut your pieces and then bake them in the oven. I've not tried this technique but it's described in various places on the web. Baking in an oven would probably give you a more uniform color, but that's my guess.
The last thing I do before I begin cutting is to sand all of the poles. To me, it's just easier to get the bulk of the sanding done on the entire culm than to sand small pieces later. And since I hate sanding, it's nice to get the worst of it out of the way!