Nine times out of ten if I break a node it was because I got it too hot. You need to heat it just until it starts to sweat and you start to smell the "hot cane" smell. If it gets charred or dark brown looking, it's too hot. Try heating it slower- I often use a heat gun on low clamped in the vise and rotate the cane constantly over it as I'm heating it. You just have to get the feel of bending the nodes, too-slow and steady, no sudden movements. Always do the major straightening before you smooth the nodes down. Another thing that helps is to get all the internodes straight before you bend the nodes, then you usually just have to bend the nodes once.
