A half-round bamboo pole is made by splitting a whole bamboo pole. This can be done by means of a splitter that is struck down with some force from one side of the bamboo pole, causing the bamboo pole to split. Or the bamboo pole goes through a sawing machine, so that it is sawed into two parts.
Both methods are used and are fairly easy to do. Bamboo has its fibers running lengthwise, which makes sawing or splitting easy. This is the reason why you cannot easily break a bamboo pole, because the fibers run exactly the other way and are quite long.
When the bamboo pole is split or sawed into two parts, you get a half-round pole. This is hollow on the inside and only has a thin partition at each node. This partition creates the hollow chambers in the bamboo pole. You can easily knock out these partitions with a hammer, so that you can use the half-round bamboo pole as a gutter or water channel, for example.
