(under subclass 331) Apparatus in which the rolling cutter element or a fixed cutting edge of the bit forms a first bore of definable diameter, and a trailing rolling cutter or fixed cutting edge increases the diameter of the first bore so that the boring outline of the bit will describe at least one peripheral axial step.
(1) Note. Since many rolling cutting bits include toothed rolling cutter elements which will individually form "steps" due to inclination of the cutter relative to the bit axis, or varying tooth lengths, such patents are excluded from this subclass and classified on other rolling cutter bit features.
SEE OR SEARCH THIS CLASS, SUBCLASS:
385+, for a nonroller type bit having a pilot cutter.
