The Collaborative International Dictionary of English v.0.48:
Crown-saw \Crown"-saw`\ (-s?`), n. [From its supposed resemblance to a crown.] (Mech.) A saw in the form of a hollow cylinder, with teeth on the end or edge, and operated by a rotative motion. [1913 Webster] Note: The trephine was the first of the class of crownsaws. --Knight. [1913 Webster]