It was at Hida Tool and Hardware in Berkeley, Calif that I encountered this strange looking cast iron tool from Japan. Turns out it is used to hand-split bamboo.
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What the splitter offers—that simple blades and froes do not—is the ability to split a culm (the woody stem of bamboo) into equal width pieces. This one splits the material into sixths, though models are available for different numbers of pieces.
Slightly less old-school: using a hand splitter to make equal width pieces
The tool is started by hammering it into the end of a culm and then using the handles to pull it through—splitting the piece from end-to-end. This kind of hand tool is fine for the craft-worker who needs to split a small number of pieces, but for greater volume it's necessary to mechanize.
Large scale producers of bamboo products split or saw culms on powered machines. Splitting is faster, and because there's no kerf, results in less waste. Once split, the pieces can be woven into baskets, fencing, and other items. Or they can be glue-laminated into large panels that can then be cut into boards, beams, and flooring.
Old-school adapted to the machine age
What's interesting about the machines is they use "dies" similar to the ones used to split material by hand. It's the same as splitting by hand, but faster and easier because a motor-driven ram pushes the bamboo through, supplying the muscle that would otherwise be provided by the user's arms.