.~ Bit with leading portion (e.g., pilot) forming smaller diameter initial bore {6}
391
.~.~ Plural larger diameter steps
DEFINITION
Classification: 175/391
(under subclass 385) Apparatus in which the cutting edges of the bit are arranged so that the boring outline of the bit will describe at least two peripheral axial steps.
SEE OR SEARCH THIS CLASS, SUBCLASS:
390, for impact type bits which describe plural larger diameter steps.
