(under subclass 398) Apparatus in which the bit is provided with means engaging the wall of the bore being formed to position the bit or direct its course.
(1) Note. For classification in this subclass the guide means must be an element other than the body of the bit which may incidentally function as a guide. However, a modification of the bit body to provide ribs, projections or the like which are specifically described as positioning or directing the bit are included in this subclass.
SEE OR SEARCH THIS CLASS, SUBCLASS:
73+, for bore wall engaging guides which act to constrain the tool to bore along a curved path.
408, and the search there noted for a bit provided with a bore wall engaging guide.
